Variable magnification optical system, and imaging device

Abstract

This variable magnification optical system comprises, in order from an object side to an image side: a positive front group comprising two or fewer lens groups having a positive refractive power; a negative front group comprising two or fewer lens groups having a negative refractive power; a mid group including one or more lens groups; and an end lens group. The lens group closest to the object side within the mid group is a first mid lens group having a positive refractive power. The variable magnification optical system includes at least one lens surface having a pole on the image side of the positive front group. The pole is a point on the lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole intersects the optical axis perpendicularly. The variable magnification optical system satisfies a predetermined conditional expression.

Description

Variable magnification optical system and imaging device

[0001] The technology of the present disclosure relates to a variable magnification optical system and an imaging apparatus.

[0002] BACKGROUND ART Conventionally, a variable magnification optical system that can be used in an imaging device such as a camera is known, such as the variable magnification optical system described in Japanese Patent Application Laid-Open No. 2015-191055.

[0003] There is a demand for variable magnification optical systems that are compact and maintain good optical performance over the entire range of magnification, and the level of these requirements is increasing year by year.

[0004] The present disclosure provides a variable magnification optical system that is compact and maintains good optical performance over the entire range of magnification, and an imaging device that includes this variable magnification optical system.

[0005] A first aspect of the present disclosure is a variable magnification optical system comprising, in order from the object side to the image side, a positive front group consisting of two or less lens groups each having positive refractive power and having positive refractive power as a whole, a negative front group consisting of two or less lens groups each having negative refractive power and having negative refractive power as a whole, an intermediate group including one or more lens groups, and a final lens group, wherein all intervals between adjacent lens groups change during magnification variation, at least one lens surface having a pole point is included on the image side of the positive front group, the pole point is a point on a lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis perpendicularly, and the lens group closest to the object side of the intermediate group is a first intermediate lens group having positive refractive power, and satisfies conditional expression (1) expressed as 0.25<Bfw / (fw×tanωw)<2 (1). Here, Bfw is the back focus in air equivalent distance of the entire system when focused on an object at infinity at the wide-angle end. The focal length of the entire system when focused on an object at infinity at the wide-angle end is fw, and the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw.

[0006] In a second aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw is defined as TLw, the conditional expression (2) expressed as 2<TLw / (fw×tan ωw)<16 (2) is satisfied.

[0007] A third aspect of the present disclosure satisfies conditional expression (3) expressed as 2.5<fPmax / fMmax<30 (3), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, and fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group, in the variable magnification optical system of the first aspect.

[0008] A fourth aspect of the present disclosure satisfies conditional expression (4) expressed as: 3.8<fPmax / (-fNmax)<40 (4) where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, and fNmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the negative front group in the variable magnification optical system of the first aspect.

[0009] In a fifth aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the maximum F-number when focused on an object at infinity at the telephoto end is FNot and the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, the variable magnification optical system satisfies conditional expression (5) expressed as 0.15<FNot / (ft / fw)<1.6 (5).

[0010] A sixth aspect of the present disclosure is the variable power optical system of the first aspect, wherein the final lens group includes at least one lens surface having a pole point.

[0011] A seventh aspect of the present disclosure is the variable magnification optical system of the sixth aspect, wherein the final lens group includes two or more lenses each including at least one lens surface having a polar point.

[0012] An eighth aspect of the present disclosure is the variable power optical system of the seventh aspect, wherein the final lens group includes three or more lenses, each of which includes at least one lens surface having a polar point.

[0013] A ninth aspect of the present disclosure is the variable magnification optical system of the sixth aspect, wherein a focusing group that moves along the optical axis during focusing is disposed closest to the image side of the intermediate group.

[0014] In a tenth aspect of the present disclosure, in the variable magnification optical system of the sixth aspect, when the sum of air spaces on the optical axis within the final lens group is defined as DEair and the distance on the optical axis from the lens surface of the final lens group closest to the object to the lens surface of the final lens group closest to the image is defined as DGE, conditional expression (6) expressed as 0≦DEair / DGE<0.45 (6) is satisfied.

[0015] In an eleventh aspect of the present disclosure, in the variable magnification optical system of the tenth aspect, when the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end is defined as TLw, and Bfw, the variable magnification optical system satisfies conditional expression (7) expressed as 0.05<DGE / TLw<0.3 (7).

[0016] In a twelfth aspect of the present disclosure, in the variable magnification optical system of the eleventh aspect, conditional expression (7-1) expressed as follows is satisfied: 0.08<DGE / TLw<0.25 (7-1).

[0017] A thirteenth aspect of the present disclosure is the variable power optical system of the sixth aspect, wherein the final lens group includes a lens having a convex shape facing the object side in the paraxial region and having at least one lens surface with a pole point.

[0018] In a fourteenth aspect of the present disclosure, in the variable magnification optical system of the first aspect, the negative front group includes a first aspherical lens that faces a concave shape toward the object side in the paraxial region and has an inflection point on its object-side lens surface where the concave-convex shape changes midway from on the optical axis toward the periphery.

[0019] In a fifteenth aspect of the present disclosure, in the variable magnification optical system of the first aspect, the negative front group includes a second aspherical lens that has a concave shape facing the image side in the paraxial region and has an inflection point on its image-side lens surface where the concave-convex shape changes midway from on the optical axis toward the periphery.

[0020] In a sixteenth aspect of the present disclosure, in the variable magnification optical system of the first aspect, the intermediate group includes a third aspherical lens that has a biconvex shape in the paraxial region and has an inflection point on the lens surface where the concave-convex shape changes midway as one moves from the optical axis to the periphery.

[0021] A seventeenth aspect of the present disclosure is the variable power optical system of the first aspect, wherein the intermediate group includes a plurality of negative lenses.

[0022] An eighteenth aspect of the present disclosure is the variable power optical system of the first aspect, wherein the positive front group includes a negative lens and a positive lens.

[0023] In a 19th aspect of the present disclosure, in the variable magnification optical system of the 14th aspect, when the radius of curvature of the object-side surface of the first aspherical lens at the position of the maximum effective diameter is defined as Ra1y and the paraxial radius of curvature of the object-side surface of the first aspherical lens is defined as Ra1c, conditional expression (8) expressed as: −10<Ra1y / Ra1c<−0.05 (8) is satisfied.

[0024] In a twentieth aspect of the present disclosure, in the variable magnification optical system of the nineteenth aspect, the lens element of the negative front group located closest to the object side is a first aspherical lens element.

[0025] In a 21st aspect of the present disclosure, in the variable magnification optical system of the 15th aspect, when the radius of curvature of the image-side surface of the second aspherical lens at the position of the maximum effective diameter is defined as Ra2y and the paraxial radius of curvature of the image-side surface of the second aspherical lens is defined as Ra2c, conditional expression (9) expressed as −1.5<Ra2y / Ra2c<0 (9) is satisfied.

[0026] In a twenty-second aspect of the present disclosure, in the variable magnification optical system of the twenty-first aspect, the lens element arranged closest to the image side in the negative front group is a second aspherical lens element.

[0027] In a 23rd aspect of the present disclosure, in the variable magnification optical system of the 16th aspect, of the third aspherical lenses included in the intermediate group, the object-side third aspherical lens arranged closest to the object side has at least one pole point on its image-side lens surface, and satisfies conditional expression (10) expressed as 0.45<PDmin / EDa3<0.95 (10). Here, PDmin is the smallest diameter of the diameters of circles centered on a point on the optical axis and passing through the respective pole points on the image-side lens surface of the object-side third aspherical lens. EDa3 is the effective diameter of the image-side surface of the object-side third aspherical lens.

[0028] In a twenty-fourth aspect of the present disclosure, in the variable magnification optical system of the twenty-third aspect, the lens element arranged closest to the object side in the intermediate group is an object-side third aspherical lens element.

[0029] In a 25th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group is taken as fPmax, the focal length of the entire system when focused on an object at infinity at the telephoto end is taken as ft, and the maximum F-number when focused on an object at infinity at the telephoto end is taken as FNot, conditional expression (11) expressed as 1.5<fPmax / (ft / FNot)<11 (11) is satisfied.

[0030] In a 26th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw is defined as TLw, the conditional expression (12) expressed as 2<TLw / fw<15 (12) is satisfied.

[0031] In a 27th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the maximum F-number in a state focused on an object at infinity at the wide-angle end is FNow, the variable magnification optical system satisfies conditional expression (13) expressed as: 0.1<tan ωw / FNow<0.6 (13).

[0032] In a 27th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the maximum F-number in a state focused on an object at infinity at the wide-angle end is FNow, the variable magnification optical system satisfies conditional expression (13) expressed as: 0.1<tan ωw / FNow<0.6 (13).

[0033] In a 28th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group is taken as fPmax, conditional expression (14) expressed as 0.05<fw / fPmax<1 (14) is satisfied.

[0034] A 29th aspect of the present disclosure is a variable power optical system according to the first aspect, wherein, when the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group is fPmax and the focal length of the entire system in a state where the lens group is focused on an object at infinity at the telephoto end is ft, the following relationship holds: 1<fPmax / (fw×ft) １／２ <15 (15) Conditional expression (15) is satisfied.

[0035] In a 30th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw is defined as TLw, and when the focal length of the entire system when focused on an object at infinity at the telephoto end is defined as ft, conditional expression (16) expressed as 0.7<TLw / ft<4 (16) is satisfied.

[0036] In a 31st aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the focal length of the entire system at the telephoto end is focused on an object at infinity, ft is satisfied, and conditional expression (17) expressed as follows is satisfied: 2<ft / fw<10 (17).

[0037] A thirty-second aspect of the present disclosure provides, in the variable power optical system of the first aspect, where fNmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the negative front group, and ft is the focal length of the entire system at the telephoto end when focused on an object at infinity, the following relationship holds: 0.15<(-fNmax) / (fw×ft). １／２ <1 (18) is satisfied.

[0038] A 33rd aspect of the present disclosure is a variable magnification optical system according to the first aspect, which satisfies conditional expression (19) expressed as follows: 0.95<TLt / TLw<2 (19). Here, TLt is the sum of the axial distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image, when focused on an object at infinity at the telephoto end, and the back focus in terms of the air-equivalent distance of the entire system. TLw is the sum of the axial distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image, when focused on an object at infinity at the wide-angle end, and Bfw.

[0039] In a thirty-fourth aspect of the present disclosure, in the variable magnification optical system of the first aspect, conditional expression (20) expressed as follows is satisfied: −0.3<fw / fE<0.6 (20) where fE is the focal length of the final lens group.

[0040] In a 35th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the focal length of the entire system at the telephoto end is focused on an object at infinity, and the focal length of the final lens group is fE, the following conditional expression (21) is satisfied: −0.4<ft / fE<1.5 (21).

[0041] A thirty-sixth aspect of the present disclosure provides, in the variable power optical system of the first aspect, where fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group, and ft is the focal length of the entire system at the telephoto end when focused on an object at infinity, the following relationship holds: 0.05<fMmax / (fw×ft) １／２ <2 (22) satisfies the conditional expression (22).

[0042] In a 37th aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group is taken as fMmax, the variable magnification optical system satisfies conditional expression (23) expressed as 0.2<fw / fMmax<1.5 (23).

[0043] In a 38th aspect of the present disclosure, in the variable magnification optical system of the first aspect, the positive front group includes a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive lens having a convex shape facing the object side are cemented together in this order from the object side to the image side, and satisfies conditional expression (24) expressed as follows: 1.94<Nn+0.01×νn<2.5 (24) Here, Nn is the refractive index with respect to the d-line of the negative meniscus lens of the cemented lens. νn is the Abbe number with a reference to the d-line of the negative meniscus lens of the cemented lens.

[0044] A thirty-ninth aspect of the present disclosure is a variable magnification optical system according to the thirty-eighth aspect, which satisfies conditional expression (25) expressed as follows: 2<Np+0.01×νp<2.6 (25) Here, the refractive index of the positive lens of the cemented lens with respect to the d-line is defined as Np. The Abbe number of the positive lens of the cemented lens with respect to the d-line is defined as νp.

[0045] In a fortieth aspect of the present disclosure, in the variable magnification optical system of the first aspect, when the average value of the Abbe numbers based on the d-line of all the positive lenses included in the positive front group is taken as νPave, the variable magnification optical system satisfies conditional expression (26) expressed as 35<νPave<96 (26).

[0046] A 41st aspect of the present disclosure is a variable magnification optical system according to the first aspect, which satisfies conditional expression (27) expressed as follows: 0.1<DEIw / TLw<0.5 (27) Here, DEIw is the sum of Bfw and the distance on the optical axis from the lens surface of the final lens group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end. TLw is the sum of Bfw and the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end.

[0047] A 42nd aspect of the present disclosure is a variable power optical system according to the first aspect, wherein the final lens group includes two or more lenses, and at least two lenses satisfy conditional expression (28) expressed by 1.85<NE+0.01×νE<2.14 (28), where NE is the refractive index of the lenses included in the final lens group with respect to the d-line and νE is the Abbe number of the lenses included in the final lens group with respect to the d-line.

[0048] A forty-third aspect of the present disclosure is the variable power optical system of the first aspect, wherein the intermediate group includes one or two focusing groups that move along the optical axis during focusing.

[0049] A forty-fourth aspect of the present disclosure is a variable magnification optical system according to the first aspect, wherein the intermediate group includes, in order from the object side to the image side, at least a first intermediate lens group and a second intermediate lens group having negative refractive power.

[0050] In a 45th aspect of the present disclosure, in the variable magnification optical system of the 44th aspect, when the focal length of the first intermediate lens group is fM1 and the focal length of the second intermediate lens group is fM2, conditional expression (29) expressed as follows is satisfied: 0.05<fM1 / (-fM2)<1.5 (29).

[0051] A forty-sixth aspect of the present disclosure is a variable magnification optical system according to the forty-fifth aspect, wherein the intermediate group includes, in order from the object side to the image side, at least a first intermediate lens group, a second intermediate lens group, and a third intermediate lens group having positive refractive power.

[0052] In a 47th aspect of the present disclosure, in the variable magnification optical system of the 46th aspect, when the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3, conditional expression (30) expressed as 0.1<(-fM2 / fM3)<4 (30) is satisfied.

[0053] In a 48th aspect of the present disclosure, in the variable magnification optical system of the first aspect, the intermediate group comprises, in order from the object side to the image side, a first intermediate lens group and a second intermediate lens group having positive refractive power.

[0054] In a 49th aspect of the present disclosure, in the variable magnification optical system of the 48th aspect, when the focal length of the first intermediate lens group is fM1 and the focal length of the second intermediate lens group is fM2, conditional expression (31) expressed as 0.05<fM1 / fM2<2 (31) is satisfied.

[0055] A 50th aspect of the present disclosure is a variable magnification optical system of the first aspect, wherein the intermediate group includes, in order from the object side to the image side, at least a first intermediate lens group, a second intermediate lens group having positive refractive power, and a third intermediate lens group having negative refractive power.

[0056] In a 51st aspect of the present disclosure, in the variable magnification optical system of the 50th aspect, when the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3, conditional expression (30A) expressed as 0.1<(-fM2 / fM3)<4 (30A) is satisfied.

[0057] A fifty-second aspect of the present disclosure is a variable magnification optical system of the first aspect, in which the intermediate group includes, in order from the object side to the image side, at least a first intermediate lens group, a second intermediate lens group having positive refractive power, and a third intermediate lens group having positive refractive power.

[0058] In a 53rd aspect of the present disclosure, in the variable magnification optical system of the 52nd aspect, when the focal length of the first intermediate lens group is fM1 and the focal length of the second intermediate lens group is fM2, conditional expression (31A) expressed as 0.02<fM1 / fM2<0.7 (31A) is satisfied.

[0059] In a 54th aspect of the present disclosure, in the variable magnification optical system of the 52nd aspect, when the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3, conditional expression (32) expressed as follows is satisfied: 0.3<fM2 / fM3<4.5 (32).

[0060] A fifty-fifth aspect of the present disclosure is a variable magnification optical system according to the fifty-third aspect, wherein the intermediate group consists of, in order from the object side to the image side, a first intermediate lens group, a second intermediate lens group, a third intermediate lens group, and a fourth intermediate lens group having positive refractive power.

[0061] In a 56th aspect of the present disclosure, in the variable magnification optical system of the 55th aspect, when the focal length of the third intermediate lens group is fM3 and the focal length of the fourth intermediate lens group is fM4, conditional expression (33) expressed as 0.3<fM3 / fM4<2.5 (33) is satisfied.

[0062] A fifty-seventh aspect of the present disclosure is an imaging device including the variable magnification optical system of any one of the first to fifty-sixth aspects.

[0063] In this specification, the terms "consisting of" and "consisting of" are intended to mean that, in addition to the listed components, other components may also be included, such as lenses that have substantially no refractive power, optical elements other than lenses, such as apertures, filters, and cover glasses, and mechanical parts, such as lens flanges, lens barrels, image sensors, and image stabilization mechanisms.

[0064] In this specification, "a group having positive refractive power" and "the group has positive refractive power" mean that the group as a whole has positive refractive power. Similarly, "a group having negative refractive power" and "the group has negative refractive power" mean that the group as a whole has negative refractive power. A "lens having positive refractive power" and a "positive lens" are synonymous. A "lens having negative refractive power" and a "negative lens" are synonymous. In this specification, the "group" is not limited to a configuration consisting of multiple lenses, and may also be a configuration consisting of only one lens.

[0065] A compound aspherical lens (a lens in which a lens (e.g., a spherical lens) and an aspherical film formed on the lens are integrally constructed and function as a single aspherical lens as a whole) is not considered a cemented lens, but is treated as a single lens. Unless otherwise specified, the radius of curvature, sign of refractive power, and surface shape of a lens including an aspherical surface are those in the paraxial region. The sign of the radius of curvature of a surface with a convex shape facing the object side is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image side is negative.

[0066] In this specification, "total system" refers to a variable magnification optical system. The "focal length" used in the conditional expressions is a paraxial focal length. The "distance on the optical axis" used in the conditional expressions is a geometric distance unless otherwise specified. The values ​​used in the conditional expressions are values ​​based on the d-line when focused on an object at infinity, unless otherwise specified.

[0067] According to the present disclosure, it is possible to provide a variable magnification optical system that is compact and maintains good optical performance over the entire range of magnification, and an imaging device that includes this variable magnification optical system.

[0068] 1A and 1B are diagrams showing a cross-sectional view and a movement locus of the configuration of a variable magnification optical system according to an embodiment, corresponding to the variable magnification optical system of Example 1. FIG. 1B is a cross-sectional view of the configuration of the variable magnification optical system of FIG. 1 at the wide-angle end, and is also a diagram for explaining symbols in conditional expressions. FIG. 1C is a diagram for explaining a pole. FIG. 1D is a diagram for explaining the position of the maximum effective aperture and the effective diameter. FIG. 1E is a diagram for explaining symbols in conditional expressions. FIG. 1F is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 1. FIG. 1G is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 2. FIG. 1H is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 3. FIG. 1H is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 3. FIG. 1I is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 4. FIG. 1I is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 5. FIG. 1I is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 5. FIG. 1I is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 6. FIG. 1I is a diagram showing a cross-sectional view and a movement locus of the configuration of the variable magnification optical system of Example 6. FIG. 10 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 7 and a movement locus. FIG. 11 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 7 and a movement locus. FIG. 12 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 7 and a movement locus. FIG. 13 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 8 and a movement locus. FIG. 14 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 9 and a movement locus. FIG. 15 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 10 and a movement locus. FIG. 16 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 11 and a movement locus. FIG. 17 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 12 and a movement locus. FIG. 18 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 13 and a movement locus. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 14 and a movement locus. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 14. FIG. 16 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 15 and a movement locus. FIG. 17 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 15. FIG. 18 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 16 and a movement locus. FIG. 19 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 16. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 17 and a movement locus. FIG. 19 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 17.FIG. 14 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 18 and a movement locus. FIG. 15 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 18. FIG. 16 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 19 and a movement locus. FIG. 17 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 19. FIG. 18 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 20 and a movement locus. FIG. 19 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 20. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 21 and a movement locus. FIG. 19 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 21. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 22 and a movement locus. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 22. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 23 and a movement locus. FIG. 19 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 23. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 24 and a movement locus. FIG. 19 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 24. FIG. 19 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 25 and a movement locus. 10A and 10B are aberration diagrams of the variable magnification optical system of Example 25. FIG. 10B is a cross-sectional view of the configuration of the variable magnification optical system of Example 26, and a diagram showing the movement locus. FIG. 10C is a cross-sectional view of the configuration of the variable magnification optical system of Example 26, and a diagram showing the movement locus. FIG. 10D is a cross-sectional view of the configuration of the variable magnification optical system of Example 27, and a diagram showing the movement locus. FIG. 10E is a cross-sectional view of the configuration of the variable magnification optical system of Example 28, and a diagram showing the movement locus. FIG. 10F is a aberration diagram of the variable magnification optical system of Example 28. FIG. 10G is a cross-sectional view of the configuration of the variable magnification optical system of Example 29, and a diagram showing the movement locus. FIG. 10H is a cross-sectional view of the configuration of the variable magnification optical system of Example 30, and a diagram showing the movement locus. FIG. 10H is a aberration diagram of the variable magnification optical system of Example 30. FIG. 10H is a cross-sectional view of the configuration of the variable magnification optical system of Example 31, and a diagram showing the movement locus. FIG. 10H is a cross-sectional view of the configuration of the variable magnification optical system of Example 32, and a diagram showing the movement locus. FIG. 10H is a aberration diagram of the variable magnification optical system of Example 32. FIG. 10 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 33 and a movement locus. FIG. 11 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 33. FIG. 12 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 34 and a movement locus. FIG. 13 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 34. FIG. 14 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 35 and a movement locus. FIG. 15 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 35. FIG. 16 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 36 and a movement locus. FIG. 17 is a diagram showing various aberration diagrams of the variable magnification optical system of Example 36. FIG. 18 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 37 and a movement locus.FIG. 10 is a diagram showing aberration diagrams of the variable magnification optical system of Example 37. FIG. 11 is a diagram showing a cross-sectional view of the configuration of the variable magnification optical system of Example 38 and a movement locus. FIG. 12 is a diagram showing aberration diagrams of the variable magnification optical system of Example 38. FIG. 13 is a diagram showing a cross-sectional view of the configuration of the variable magnification optical system of Example 39 and a movement locus. FIG. 14 is a diagram showing aberration diagrams of the variable magnification optical system of Example 39. FIG. 15 is a diagram showing a cross-sectional view of the configuration of the variable magnification optical system of Example 40 and a movement locus. FIG. 16 is a diagram showing aberration diagrams of the variable magnification optical system of Example 40. FIG. 17 is a perspective view of the front side of an imaging device according to an embodiment. FIG. 18 is a perspective view of the back side of an imaging device according to an embodiment.

[0069] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0070] FIG. 1 shows a cross-sectional view of the configuration and light beams of a variable magnification optical system according to an embodiment of the present disclosure, as well as a movement trajectory. In FIG. 1 , the upper row labeled "Wide" shows the wide-angle end state, and the lower row labeled "Tele" shows the telephoto end state. In FIG. 1 , the light beams are an axial light beam wa at the wide-angle end and a light beam wb at the maximum half angle of view ωw, and an axial light beam ta at the telephoto end and a light beam tb at the maximum half angle of view. FIG. 2 shows a cross-sectional view of the configuration of the variable magnification optical system of FIG. 1 at the wide-angle end. In FIGS. 1 and 2 , the state is shown in focus on an object at infinity, with the left side being the object side and the right side being the image side. The example shown in FIGS. 1 and 2 corresponds to the variable magnification optical system of Example 1, which will be described later. The following description will be primarily based on FIG. 1 , with reference to FIG. 2 as needed.

[0071] The variable magnification optical system of the present disclosure comprises, in order from the object side to the image side along the optical axis Z, a positive front group GP, a negative front group GN, an intermediate group GM including one or more lens groups, and a final lens group GE. The positive front group GP comprises two or less lens groups having positive refractive power, and has positive refractive power as a whole. The negative front group GN comprises two or less lens groups having negative refractive power, and has negative refractive power as a whole. When magnification is varied, all of the spacings between adjacent lens groups change. The lens group closest to the object side of the intermediate group GM is a first intermediate lens group GM1 having positive refractive power. The above configuration is advantageous for achieving a high variable magnification ratio while suppressing aberration fluctuations during magnification variation.

[0072] In this specification, a lens group is defined as a group whose distance in the optical axis direction from adjacent groups changes when the magnification is changed. When the magnification is changed, the distance between adjacent lenses within a lens group does not change. In other words, a "lens group" is a component of a variable magnification optical system, and is a portion that includes at least one lens separated by an air gap that changes when the magnification is changed. When the magnification is changed, each lens group is moved or fixed individually. A "lens group" may also include components other than lenses that do not have refractive power, such as an aperture diaphragm St.

[0073] As an example, each group in the variable magnification optical system of FIG. 1 is configured as follows, with its detailed configuration shown in FIG. 2. The positive front group GP consists of one lens group. The lens groups that make up the positive front group GP, from the object side to the image side, consist of two lenses, lenses L11 and L12. The negative front group GN consists of one lens group. The lens groups that make up the negative front group GN, from the object side to the image side, consist of four lenses, lenses L21 to L24. The intermediate group GM, from the object side to the image side, consists of two lens groups, a first intermediate lens group GM1 and a second intermediate lens group GM2. The first intermediate lens group GM1, from the object side to the image side, consists of an aperture stop St and six lenses, lenses L31 to L36. The second intermediate lens group GM2, from the object side to the image side, consists of two lenses, lenses L41 and L42. The final lens group GE is made up of six lenses, lenses L51 to L56, in that order from the object side to the image side. Note that the aperture stop St shown in Figures 1 and 2 does not indicate its size or shape, but its position in the optical axis direction.

[0074] In the example of Fig. 1, during magnification variation, the positive front group GP, the negative front group GN, the first intermediate lens group GM1, and the second intermediate lens group GM2 move along the optical axis Z while changing the spacing between adjacent lens groups, and the final lens group GE is fixed relative to the image plane Sim. In Fig. 1, between the upper and lower diagrams, solid arrows indicate the approximate movement locus of each lens group that moves during magnification variation from the wide-angle end to the telephoto end.

[0075] It is preferable that the positive front group GP includes a negative lens and a positive lens, which is advantageous for correcting chromatic aberration.

[0076] It is preferable that the positive front group GP include a cemented lens in which a negative meniscus lens element with a convex surface facing the object side and a positive lens element with a convex surface facing the object side are cemented together in this order from the object side to the image side, which is advantageous for correcting chromatic aberration of magnification at the wide-angle end and axial chromatic aberration at the telephoto end.

[0077] It is preferable that the middle group GM includes a plurality of negative lenses, which is advantageous for suppressing various aberrations during zooming.

[0078] The variable magnification optical system of the present disclosure is configured to include at least one lens surface having a polar point on the image side of the positive front group GP, which makes it easy to achieve significant miniaturization of the variable magnification optical system while effectively correcting various aberrations over the entire range of magnification.

[0079] The term "lens surface" does not necessarily refer to an air-contact surface, but also includes a surface that is not in contact with air, such as the cemented surface of a cemented lens, and includes the boundary surface of lenses made of different materials. Furthermore, a "lens surface" is a surface on a lens through which light rays used for imaging pass.

[0080] Furthermore, in this specification, a "pole point" refers to a point on a lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis Z perpendicularly. FIG. 3 shows an enlarged view of the final lens group GE of the variable magnification optical system of FIG. 1 , taken along a cross section including the optical axis Z. FIG. 3 also shows the axial light beam wa at the wide-angle end and the light beam wb at the maximum half angle of view ωw that pass through the final lens group GE. As an example, FIG. 3 shows a pole point P0 on the image-side lens surface of lens L52, and the tangent plane Tp of this lens surface at the pole point P0 is indicated by a dotted line. The tangent plane Tp intersects the optical axis Z perpendicularly. Note that the final lens group GE in FIG. 3 has other pole points in addition to the pole point P0 shown in the figure, but the reference symbols for the other pole points have been omitted.

[0081] It is preferable that the final lens group GE includes at least one lens surface having a pole point. In this case, it becomes easy to achieve a significant reduction in the size of the variable magnification optical system while effectively correcting various aberrations. To make this effect more pronounced, it is more preferable that the final lens group GE includes two or more lenses, and even more preferable that it includes three or more lenses, each of which has at least one lens surface having a pole point.

[0082] It is preferable that the final lens group GE has a configuration including at least one lens having a convex shape facing the object side in the paraxial region and having a polar point. In this configuration, the lens surface having a polar point may be at least one of a lens surface on the object side and a lens surface on the image side. With this configuration, it is easy to achieve a compact variable magnification optical system while correcting off-axis aberrations without worsening spherical aberration.

[0083] The negative front group GN preferably includes a first aspherical lens element that has a concave shape facing the object side in the paraxial region and has an inflection point on its object-side lens surface where the concave shape changes midway from the optical axis toward the periphery. This is advantageous for suppressing fluctuations in astigmatism during zooming. In the example of Figure 2, lens element L21 corresponds to the first aspherical lens element.

[0084] An inflection point is a point where the surface shape changes from convex to concave or from concave to convex, i.e., where the sign of the radius of curvature changes. By having an inflection point on the lens surface, the refractive power of the peripheral part of the lens can be determined independently of the refractive power of the paraxial region.

[0085] It is preferable that the lens element in the negative front group GN that is closest to the object side be a first aspherical lens element, which makes it easier to suppress curvature of field at the wide-angle end.

[0086] It is preferable that the negative front group GN includes a second aspherical lens element that has a concave shape facing the image side in the paraxial region and has an inflection point on its image-side lens surface where the concave shape changes midway from the optical axis toward the periphery. In this case, it becomes easy to correct spherical aberration at the telephoto end while maintaining a sufficient zoom ratio. In the example of Figure 2, lens element L24 corresponds to the second aspherical lens element.

[0087] It is preferable that the lens element in the negative front group GN located closest to the image side be a second aspherical lens element, which makes it easier to correct spherical aberration at the telephoto end while maintaining a sufficient zoom ratio.

[0088] It is preferable that the middle group GM includes a third aspherical lens element that is biconvex in the paraxial region and has an inflection point on its lens surface where the concave-convex shape changes midway from the optical axis toward the periphery. In this case, correction of high-order spherical aberration at the telephoto end is facilitated. In this specification, "high-order" in relation to aberrations means fifth order or higher, and "low-order" in relation to aberrations means third order or lower.

[0089] In the example of Fig. 2, lens L36, which is the lens closest to the image in the first intermediate lens group GM1, corresponds to the third aspherical lens. However, in the variable magnification optical system of the present disclosure, unlike the example of Fig. 2, the lens located closest to the object in the intermediate lens group GM may be configured as the object-side third aspherical lens. In this case, it becomes easier to correct high-order spherical aberration at the telephoto end.

[0090] The variable magnification optical system of the present disclosure may be configured to include a focusing group that moves along the optical axis Z during focusing. Focusing is achieved by the movement of the focusing group. For example, the intermediate group GM may be configured to include one or two focusing groups. By placing a focusing group in the intermediate group GM, breathing can be suppressed.

[0091] In the example of Fig. 1, the focusing group is made up of the second intermediate lens group GM2. The parentheses and right-pointing arrow attached to the second intermediate lens group GM2 in the lower diagram of Fig. 1 indicate that the second intermediate lens group GM2 is the focusing group, and that it moves in the direction in which it moves when focusing from an object at infinity to the closest object. Note that the focusing group functions over the entire magnification range, including the wide-angle end state, but in Fig. 1, the above arrow is only included in the lower diagram to avoid complicating the diagram.

[0092] If the final lens group GE includes at least one lens surface having a polar point, the focusing group may be arranged closest to the intermediate group GM on the image side. By arranging the focusing group adjacent to the final lens group GE, which includes a lens having a polar point, in this way, it becomes easier to suppress aberration fluctuations that occur during focusing. Furthermore, because it becomes easier to suppress aberration fluctuations that occur during focusing, it becomes possible to impart a large refractive power to the focusing group, thereby shortening the stroke of the focusing group during focusing.

[0093] 1 includes only one focusing group, the variable magnification optical system of the present disclosure may include multiple focusing groups. If the variable magnification optical system includes two focusing groups that move while changing the distance between them during focusing, the amount of movement of each focusing group during focusing can be reduced.

[0094] Next, preferred and possible configurations regarding the conditional expressions of the variable magnification optical system of the present disclosure will be described. Note that in the following explanation of the conditional expressions, to avoid redundant explanation, the same symbols are used for elements with the same definitions, and duplicate explanations of symbols will be omitted. Also, to avoid redundant explanation, hereinafter, "the variable magnification optical system of the present disclosure" will also be simply referred to as "the variable magnification optical system."

[0095] It is preferable that the variable magnification optical system satisfy the following conditional expression (1). Here, the back focus in the air-equivalent distance of the entire system when focused on an object at infinity at the wide-angle end is defined as Bfw. The focal length of the entire system when focused on an object at infinity at the wide-angle end is defined as fw. The maximum half angle of view when focused on an object at infinity at the wide-angle end is defined as ωw. The back focus in the air-equivalent distance is the air-equivalent distance on the optical axis from the lens surface closest to the image side of the variable magnification optical system to the image plane Sim. tan is the tangent. As an example, FIG. 2 shows the back focus Bfw, and FIG. 1 shows the maximum half angle of view ωw. By ensuring that the corresponding value of conditional expression (1) is not equal to or less than the lower limit, the back focus Bfw does not become too short, making it easy to attach a mount exchange mechanism. By ensuring that the corresponding value of conditional expression (1) is not equal to or greater than the upper limit, the back focus Bfw does not become too long, making it easy to achieve compactness. 0.25<Bfw / (fw×tanωw)<2 (1)

[0096] In order to obtain better characteristics, the lower limit of conditional expression (1) is more preferably set to 0.3, even more preferably 0.35, even more preferably 0.38, and even more preferably 0.4. In order to obtain better characteristics, the upper limit of conditional expression (1) is more preferably set to 1.8, even more preferably 1.6, even more preferably 1.4, and even more preferably 1.2. For example, it is more preferable that the variable magnification optical system satisfies the following conditional expression (1-1): 0.35<Bfw / (fw×tanωw)<1.6 (1-1)

[0097] It is preferable that the variable magnification optical system satisfy the following conditional expression (2). Here, TLw is the sum of the distance on the optical axis from the lens surface of the positive front group GP closest to the object to the lens surface of the final lens group GE closest to the image when focused on an object at infinity at the wide-angle end, and Bfw. TLw is the total optical length when focused on an object at infinity at the wide-angle end. As an example, FIG. 2 shows the above total optical length TLw. By ensuring that the corresponding value of conditional expression (2) is not equal to or less than the lower limit, it is advantageous to suppress various aberrations over the entire range of magnification. By ensuring that the corresponding value of conditional expression (2) is not equal to or greater than the upper limit, it is advantageous to shorten the total optical length TLw. 2<TLw / (fw×tanωw)<16 (2)

[0098] In order to obtain better characteristics, the lower limit of conditional expression (2) is more preferably set to 2.2, even more preferably to 2.3, even more preferably to 2.4, even more preferably to 2.5, even more preferably to 2.6, even more preferably to 2.7, even more preferably to 2.8, even more preferably to 2.9, and even more preferably to 3. In order to obtain better characteristics, the upper limit of conditional expression (2) is more preferably set to 9.7, even more preferably to 9.2, even more preferably to 8.7, even more preferably to 8.2, even more preferably to 7.7, even more preferably to 7.2, even more preferably to 6.7, even more preferably to 6.3, and even more preferably to 6. For example, it is more preferable that the variable magnification optical system satisfy at least one of the following conditional expressions (2-1), (2-2), (2-3), and (2-4). 2.2<TLw / (fw×tanωw)<9.7 (2-1) 2.3<TLw / (fw×tanωw)<9.2 (2-2) 2.4<TLw / (fw×tanωw)<8.7 (2-3) 3<TLw / (fw×tanωw)<6 (2-4)

[0099] It is preferable that the variable magnification optical system satisfy the following conditional expression (3). Here, fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group GP. fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the middle group GM. By ensuring that the corresponding value of conditional expression (3) is not below the lower limit, the refractive power of the middle group GM does not become too weak, making it easy to suppress the amount of movement of the middle group GM when varying magnification. By ensuring that the corresponding value of conditional expression (3) is not above the upper limit, the refractive power of the positive front group GP does not become too weak, making it easy to suppress an increase in the size of the positive front group GP. 2.5<fPmax / fMmax<30 (3)

[0100] In order to obtain better characteristics, the lower limit of conditional expression (3) is more preferably set to 3.2, even more preferably to 4, even more preferably to 4.2, even more preferably to 4.4, even more preferably to 4.6, even more preferably to 4.8, and even more preferably to 5. In order to obtain better characteristics, the upper limit of conditional expression (3) is more preferably set to 25, even more preferably to 20, even more preferably to 18, even more preferably to 16, even more preferably to 14, even more preferably to 12, and even more preferably to 10.5. For example, it is more preferable that the variable magnification optical system satisfy at least one of the following conditional expressions (3-1), (3-2), and (3-3): 3.2<fPmax / fMmax<25 (3-1) 4.2<fPmax / fMmax<18 (3-2) 4.6<fPmax / fMmax<14 (3-3)

[0101] It is preferable that the variable magnification optical system satisfy the following conditional expression (4). Here, fNmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the negative front group GN. By ensuring that the corresponding value of conditional expression (4) is not below the lower limit, the refractive power of the negative front group GN does not become too weak, making it easy to suppress the amount of movement of the negative front group GN when varying magnification. By ensuring that the corresponding value of conditional expression (4) is not above the upper limit, the refractive power of the positive front group GP does not become too weak, making it easy to suppress an increase in the size of the positive front group GP. 3.8<fPmax / (-fNmax)<40 (4)

[0102] In order to obtain better characteristics, the lower limit of conditional expression (4) is more preferably set to 3.9, even more preferably to 4, even more preferably to 4.1, and even more preferably to 4.2. In order to obtain better characteristics, the upper limit of conditional expression (4) is more preferably set to 20, even more preferably to 15, even more preferably to 10.5, and even more preferably to 8.

[0103] It is preferable that the variable magnification optical system satisfies the following conditional expression (5). Here, FNot is the maximum F-number when focused on an object at infinity at the telephoto end. ft is the focal length of the entire system when focused on an object at infinity at the telephoto end. Making sure that the corresponding value of conditional expression (5) is not equal to or less than the lower limit is advantageous for reducing the size of the entire optical system, or for suppressing various aberrations, particularly at the telephoto end. Making sure that the corresponding value of conditional expression (5) is not equal to or greater than the upper limit makes it easier to obtain sufficient brightness at the telephoto end. 0.15<FNot / (ft / fw)<1.6 (5)

[0104] To obtain better characteristics, the lower limit of conditional expression (5) is more preferably set to 0.2, even more preferably to 0.25, and even more preferably to 0.3. To obtain better characteristics, the upper limit of conditional expression (5) is more preferably set to 1.4, even more preferably to 1.2, and even more preferably to 1.1. For example, it is more preferable that the variable magnification optical system satisfies the following conditional expression (5-1): 0.25<FNot / (ft / fw)<1.2 (5-1)

[0105] It is preferable that the variable magnification optical system satisfies the following conditional expression (6). Here, DEair is the sum of the air spaces on the optical axis within the final lens group GE. DGE is the distance on the optical axis from the lens surface of the final lens group GE closest to the object to the lens surface of the final lens group GE closest to the image. As an example, FIG. 2 shows the above distance DGE. The lower limit of conditional expression (6) is DEair≧0 and DGE>0, so DEair / DGE≧0. By ensuring that the corresponding value of conditional expression (6) does not exceed the upper limit, it is advantageous to suppress various aberrations throughout the entire variable magnification range. 0≦DEair / DGE<0.45 (6)

[0106] In order to obtain better characteristics, the upper limit of conditional expression (6) is more preferably set to 0.35, even more preferably 0.25, even more preferably 0.15, and even more preferably 0.1.

[0107] It is preferable that the variable magnification optical system satisfies the following conditional expression (7). By ensuring that the corresponding value of conditional expression (7) is not below the lower limit, it becomes easy to ensure the optical path length for correcting various aberrations in the final lens group GE while realizing a significant reduction in the size of the variable magnification optical system. By ensuring that the corresponding value of conditional expression (7) is not above the upper limit, it becomes possible to prevent the thickness of the final lens group GE in the optical axis direction from becoming too large, which is advantageous for shortening the total optical length TLw. 0.05<DGE / TLw<0.3 (7)

[0108] In order to obtain better characteristics, the lower limit of conditional expression (7) is more preferably set to 0.07, even more preferably 0.08, even more preferably 0.09, even more preferably 0.1, even more preferably 0.11, and even more preferably 0.12. In order to obtain better characteristics, the upper limit of conditional expression (7) is more preferably set to 0.27, even more preferably 0.25, even more preferably 0.23, even more preferably 0.21, even more preferably 0.19, and even more preferably 0.17. For example, it is more preferable that the variable magnification optical system satisfies the following conditional expression (7-1), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (7-2): 0.08<DGE / TLw<0.25 (7-1) 0.09<DGE / TLw<0.23 (7-2)

[0109] In a configuration in which the negative front group GN includes a first aspherical lens, it is preferable that the variable magnification optical system satisfy the following conditional expression (8). Here, Ra1y is the radius of curvature of the object-side surface of the first aspherical lens at the position of the maximum effective diameter. Ra1c is the paraxial radius of curvature of the object-side surface of the first aspherical lens. By ensuring that the corresponding value of conditional expression (8) is not equal to or less than the lower limit, the positive refractive power at the periphery of the lens does not become too weak, making it easy to suppress curvature of field at the wide-angle end. By ensuring that the corresponding value of conditional expression (8) is not equal to or greater than the upper limit, the negative refractive power in the paraxial region does not become too weak, which is advantageous for ensuring a high variable magnification ratio. -10<Ra1y / Ra1c<-0.05 (8)

[0110] In order to obtain better characteristics, the lower limit of conditional expression (8) should preferably be set to −7, more preferably to −4, even more preferably to −1.5, and even more preferably to −1. In order to obtain better characteristics, the upper limit of conditional expression (8) should preferably be set to −0.1, more preferably to −0.15, even more preferably to −0.2, and even more preferably to −0.25.

[0111] Here, the "position of the maximum effective diameter" in this specification will be explained with reference to FIG. 4. FIG. 4 is an explanatory diagram. In FIG. 4, the left side is the object side and the right side is the image side. FIG. 4 shows an on-axis light beam Xa and an off-axis light beam Xb passing through the lens Lx. In the example of FIG. 4, the upper ray Xb1 of the off-axis light beam Xb is the outermost ray. Here, "outside" refers to the radially outward direction centered on the optical axis Z, i.e., the side away from the optical axis Z. In this specification, the position of intersection between this outermost ray and the lens surface is the position Px of the maximum effective diameter. Furthermore, twice the distance from the position Px of the maximum effective diameter to the optical axis Z is the effective diameter ED of the object-side surface of the lens Lx. Note that in the example of FIG. 4, the upper ray of the off-axis light beam Xb is the outermost ray, but which ray is the outermost ray varies depending on the optical system.

[0112] In a configuration in which the negative front group GN includes a second aspherical lens, it is preferable that the variable magnification optical system satisfy the following conditional expression (9). Here, the radius of curvature of the image-side surface of the second aspherical lens at the position of the maximum effective diameter is defined as Ra2y. The paraxial radius of curvature of the image-side surface of the second aspherical lens is defined as Ra2c. By ensuring that the corresponding value of conditional expression (9) is not equal to or less than the lower limit, the positive refractive power at the periphery of the lens does not become too weak, making it easy to correct spherical aberration at the telephoto end. By ensuring that the corresponding value of conditional expression (9) is not equal to or greater than the upper limit, the negative refractive power in the paraxial region does not become too weak, which is advantageous for ensuring a high variable magnification ratio. -1.5<Ra2y / Ra2c<0 (9)

[0113] In order to obtain better characteristics, the lower limit of conditional expression (9) should preferably be set to -1.4, more preferably to -1.3, even more preferably to -1.2, and even more preferably to -1.1. In order to obtain better characteristics, the upper limit of conditional expression (9) should preferably be set to -0.02, more preferably to -0.04, even more preferably to -0.06, and even more preferably to -0.08.

[0114] When the intermediate group GM includes a third aspherical lens, the third aspherical lens arranged closest to the object among the third aspherical lenses included in the intermediate group GM is referred to as the object-side third aspherical lens. In a configuration in which the object-side third aspherical lens has at least one polar point on its image-side lens surface, the variable magnification optical system preferably satisfies the following conditional expression (10). Here, PDmin is the smallest diameter of the diameters of circles centered on a point on the optical axis and passing through the respective polar points on the image-side lens surface of the object-side third aspherical lens. EDa3 is the effective diameter of the image-side surface of the object-side third aspherical lens. By ensuring that the corresponding value of conditional expression (10) is not equal to or less than the lower limit, it becomes easy to suppress the effect on low-order spherical aberrations. By ensuring that the corresponding value of conditional expression (10) is not equal to or greater than the upper limit, it becomes easy to correct high-order spherical aberrations at the telephoto end. 0.45<PDmin / EDa3<0.95 (10)

[0115] In order to obtain better characteristics, the lower limit of conditional expression (10) should preferably be set to 0.5, more preferably 0.54, even more preferably 0.57, and even more preferably 0.6.In order to obtain better characteristics, the upper limit of conditional expression (10) should preferably be set to 0.9, even more preferably 0.87, even more preferably 0.84, and even more preferably 0.82.

[0116] FIG. 5 schematically shows an example of a third aspherical lens La3 in a cross section including the optical axis Z. FIG. 5 is an explanatory diagram, and the shape of the lens surface is exaggerated for ease of understanding. In FIG. 5, the left side is the object side, and the right side is the image side. The third aspherical lens La3 in FIG. 5 is configured rotationally symmetrically with the optical axis Z as the central axis, and has two pole points, P1 and P2, on the image-side lens surface. Note that pole points are counted by their radial position around the optical axis Z. That is, a set of pole points at the same radial position is counted as one pole point, and two pole points at different radial positions are considered to be two pole points. On the image-side lens surface of the third aspherical lens La3 in FIG. 5, the diameter of a circle centered on a point on the optical axis and passing through pole point P1 is PD1, and the diameter of a circle centered on a point on the optical axis and passing through pole point P2 is PD2. 5 shows the diameters PD1 and PD2, as well as the effective diameter EDa3 of the image-side surface of the third aspherical lens La3. Since the smallest of the diameters PD1 and PD2 is the diameter PD1, when the third aspherical lens La3 is the object-side third aspherical lens, the diameter PD1 corresponds to the above-mentioned PDmin.

[0117] It is preferable that the variable magnification optical system satisfies the following conditional expression (11). By ensuring that the corresponding value of conditional expression (11) is not below the lower limit, it is advantageous for improving performance. By ensuring that the corresponding value of conditional expression (11) is not above the upper limit, it is advantageous for reducing the size of the positive front group GP, since the refractive power of the positive front group GP does not become too weak. 1.5<fPmax / (ft / FNot)<11 (11)

[0118] In order to obtain better characteristics, the lower limit of conditional expression (11) should preferably be set to 2, more preferably to 2.5, and even more preferably to 3. In order to obtain better characteristics, the upper limit of conditional expression (11) should preferably be set to 10, more preferably to 8, and even more preferably to 7.

[0119] It is preferable that the variable magnification optical system satisfies the following conditional expression (12). By ensuring that the corresponding value of conditional expression (12) is not equal to or less than the lower limit, it is advantageous for suppressing various aberrations. By ensuring that the corresponding value of conditional expression (12) is not equal to or greater than the upper limit, it is advantageous for shortening the total optical length TLw. 2<TLw / fw<15 (12)

[0120] In order to obtain better characteristics, the lower limit of conditional expression (12) should preferably be set to 2.4, more preferably to 2.7, and even more preferably to 3. In order to obtain better characteristics, the upper limit of conditional expression (12) should preferably be set to 12, more preferably to 9, and even more preferably to 7.

[0121] When the maximum F-number when focused on an object at infinity at the wide-angle end is FNow, it is preferable that the variable magnification optical system satisfies the following conditional expression (13). By ensuring that the corresponding value of conditional expression (13) is not equal to or less than the lower limit, it becomes easy to reduce the maximum F-number at the wide-angle end while widening the angle of view at the wide-angle end. By ensuring that the corresponding value of conditional expression (13) is not equal to or greater than the upper limit, it becomes advantageous to suppress an increase in the number of lenses and an increase in the size of the optical system while obtaining good optical performance. 0.1<tan ωw / FNow<0.6 (13)

[0122] In order to obtain better characteristics, the lower limit of conditional expression (13) should preferably be set to 0.12, more preferably 0.14, even more preferably 0.16, even more preferably 0.18, and even more preferably 0.2. In order to obtain better characteristics, the upper limit of conditional expression (13) should preferably be set to 0.57, even more preferably 0.54, even more preferably 0.51, even more preferably 0.48, and even more preferably 0.45.

[0123] It is preferable that the variable magnification optical system satisfies the following conditional expression (14). By ensuring that the corresponding value of conditional expression (14) is not equal to or less than the lower limit, it is advantageous for shortening the overall optical length. By ensuring that the corresponding value of conditional expression (14) is not equal to or greater than the upper limit, it is advantageous for ensuring the angle of view at the wide-angle end. 0.05<fw / fPmax<1 (14)

[0124] In order to obtain better characteristics, the lower limit of conditional expression (14) is more preferably set to 0.07, even more preferably 0.09, even more preferably 0.1, even more preferably 0.11, even more preferably 0.12, and even more preferably 0.13. In order to obtain better characteristics, the upper limit of conditional expression (14) is more preferably set to 0.9, even more preferably 0.8, even more preferably 0.7, even more preferably 0.6, even more preferably 0.5, and even more preferably 0.4.

[0125] It is preferable that the variable magnification optical system satisfy the following conditional expression (15). By ensuring that the corresponding value of conditional expression (15) is not below the lower limit, the refractive power of the positive front group GP does not become too strong, which is advantageous for suppressing aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (15) is not above the upper limit, the refractive power of the positive front group GP does not become too weak, which is advantageous for making the positive front group GP more compact. 1<fPmax / (fw×ft) １／２ <15 (15)

[0126] In order to obtain better characteristics, the lower limit of conditional expression (15) should preferably be set to 2, more preferably to 2.5, and even more preferably to 3. In order to obtain better characteristics, the upper limit of conditional expression (15) should preferably be set to 12, more preferably to 10, and even more preferably to 9.

[0127] It is preferable that the variable magnification optical system satisfies the following conditional expression (16). By ensuring that the corresponding value of conditional expression (16) is not equal to or less than the lower limit, it becomes easy to suppress various aberrations at the wide-angle end. By ensuring that the corresponding value of conditional expression (16) is not equal to or greater than the upper limit, it becomes easy to shorten the total optical length TLw at the wide-angle end. 0.7<TLw / ft<4 (16)

[0128] In order to obtain better characteristics, the lower limit of conditional expression (16) should preferably be set to 0.9, and more preferably to 1.1, and the upper limit of conditional expression (16) should preferably be set to 3, and more preferably to 2.

[0129] It is preferable that the variable magnification optical system satisfies the following conditional expression (17). By ensuring that the corresponding value of conditional expression (17) is not below the lower limit, the variable magnification ratio does not become too low, and the variable magnification optical system can fully demonstrate its value. By ensuring that the corresponding value of conditional expression (17) is not above the upper limit, the variable magnification ratio does not become too high, and the movement amount of the lens group that moves during magnification change can be prevented from becoming excessive, which is advantageous for reducing the size of the entire optical system. 2<ft / fw<10 (17)

[0130] In order to obtain better characteristics, the lower limit of conditional expression (17) should preferably be set to 2.3, more preferably to 2.5, and even more preferably to 2.7. In order to obtain better characteristics, the upper limit of conditional expression (17) should preferably be set to 9, more preferably to 8, and even more preferably to 7.

[0131] It is preferable that the variable magnification optical system satisfy the following conditional expression (18). By ensuring that the corresponding value of conditional expression (18) is not below the lower limit, the refractive power of the negative front group GN does not become too strong, and the amount of aberration due to curvature of field generated in the negative front group GN can be suppressed, which is advantageous for aberration correction when varying magnification. By ensuring that the corresponding value of conditional expression (18) is not above the upper limit, the refractive power of the negative front group GN does not become too weak, and the amount of movement of the negative front group GN when varying magnification can be suppressed. This prevents the total optical length from becoming too long, which is advantageous for size reduction. 0.15<(-fNmax) / (fw×ft) １／２ <1 (18)

[0132] In order to obtain better characteristics, the lower limit of conditional expression (18) should preferably be set to 0.2, more preferably to 0.25, and even more preferably to 0.3.In order to obtain better characteristics, the upper limit of conditional expression (18) should preferably be set to 0.8, more preferably to 0.6, and even more preferably to 0.5.

[0133] It is preferable that the variable magnification optical system satisfy the following conditional expression (19). Here, TLt is the sum of the axial distance from the lens surface of the positive front group GP closest to the object to the lens surface of the final lens group GE closest to the image when focused on an object at infinity at the telephoto end, and the back focus in terms of the air-equivalent distance of the entire system when focused on an object at infinity at the telephoto end. TLt is the total optical length when focused on an object at infinity at the telephoto end. By ensuring that the corresponding value of conditional expression (19) is not equal to or less than the lower limit, it is advantageous to suppress various aberrations throughout the entire range of magnification. By ensuring that the corresponding value of conditional expression (19) is not equal to or greater than the upper limit, it is advantageous to miniaturization because the total optical length when focused on an object at infinity at the telephoto end does not become too long. 0.95<TLt / TLw<2 (19)

[0134] In order to obtain better characteristics, the lower limit of conditional expression (19) should preferably be set to 1.1, and more preferably to 1.25, and the upper limit of conditional expression (19) should preferably be set to 1.7, and more preferably to 1.5.

[0135] When the focal length of the final lens group GE is fE, it is preferable that the variable magnification optical system satisfies the following conditional expression (20). By ensuring that the corresponding value of conditional expression (20) is not equal to or less than the lower limit, the total optical length TLw at the wide-angle end can be easily shortened, which is advantageous for size reduction. By ensuring that the corresponding value of conditional expression (20) is not equal to or greater than the upper limit, it is advantageous for suppressing spherical aberration at the wide-angle end. -0.3<fw / fE<0.6 (20)

[0136] In order to obtain better characteristics, the lower limit of conditional expression (20) should preferably be set to −0.2, more preferably to −0.15, even more preferably to −0.1, and even more preferably to −0.05. In order to obtain better characteristics, the upper limit of conditional expression (20) should preferably be set to 0.5, even more preferably to 0.4, even more preferably to 0.3, and even more preferably to 0.2.

[0137] It is preferable that the variable magnification optical system satisfies the following conditional expression (21). By ensuring that the corresponding value of conditional expression (21) is not equal to or less than the lower limit, it becomes easy to shorten the total optical length at the telephoto end, which is advantageous for size reduction. By ensuring that the corresponding value of conditional expression (21) is not equal to or greater than the upper limit, it becomes advantageous for suppressing spherical aberration at the telephoto end. -0.4<ft / fE<1.5 (21)

[0138] In order to obtain better characteristics, the lower limit of conditional expression (21) should preferably be set to −0.3, more preferably to −0.2, even more preferably to −0.1, and even more preferably to −0.05.In order to obtain better characteristics, the upper limit of conditional expression (21) should preferably be set to 1.2, even more preferably to 0.9, even more preferably to 0.6, and even more preferably to 0.3.

[0139] It is preferable that the variable magnification optical system satisfy the following conditional expression (22). By ensuring that the corresponding value of conditional expression (22) is not below the lower limit, the refractive power of the middle group GM does not become too strong, and the amount of aberration due to curvature of field generated in the middle group GM can be suppressed, which is advantageous for aberration correction during magnification. By ensuring that the corresponding value of conditional expression (22) is not above the upper limit, the refractive power of the middle group GM does not become too weak, and the amount of movement of the middle group GM during magnification can be suppressed. This prevents the total optical length from becoming too long, which is advantageous for size reduction. 0.05<fMmax / (fw×ft) １／２ <2 (22)

[0140] In order to obtain better characteristics, the lower limit of conditional expression (22) should preferably be set to 0.2, more preferably 0.3, even more preferably 0.4, and even more preferably 0.5.In order to obtain better characteristics, the upper limit of conditional expression (22) should preferably be set to 1.8, more preferably 1.6, even more preferably 1.5, and even more preferably 1.4.

[0141] It is preferable that the variable magnification optical system satisfy the following conditional expression (23). By ensuring that the corresponding value of conditional expression (23) is not below the lower limit, the refractive power of the middle group GM does not become too weak, and the amount of movement of the middle group GM during variable magnification can be reduced. This prevents the total optical length from becoming too long, which is advantageous for size reduction. By ensuring that the corresponding value of conditional expression (23) is not above the upper limit, the refractive power of the middle group GM does not become too strong, and the amount of aberration due to curvature of field generated in the middle group GM can be reduced, which is advantageous for aberration correction during variable magnification. 0.2<fw / fMmax<1.5 (23)

[0142] In order to obtain better characteristics, the lower limit of conditional expression (23) should preferably be set to 0.3, more preferably to 0.4, and even more preferably to 0.45, while the upper limit of conditional expression (23) should preferably be set to 1.3, more preferably to 1.1, and even more preferably to 0.9.

[0143] In a configuration in which the positive front group GP includes a cemented lens in which a negative meniscus lens with a convex shape facing the object side and a positive lens with a convex shape facing the object side are cemented together in this order from the object side to the image side, it is preferable that the variable magnification optical system satisfy the following conditional expression (24). Here, the refractive index of the negative meniscus lens in the cemented lens with respect to the d-line is Nn. The Abbe number of the negative meniscus lens in the cemented lens with respect to the d-line is vn. By ensuring that the corresponding value of conditional expression (24) is not equal to or less than the lower limit, materials other than those with low refractive indexes and low Abbe numbers can be selected, thereby facilitating correction of lateral chromatic aberration at the wide-angle end. By ensuring that the corresponding value of conditional expression (24) is not equal to or greater than the upper limit, materials other than those with high refractive indexes and high Abbe numbers can be selected, thereby allowing materials with a low specific gravity to be selected, facilitating weight reduction. Furthermore, since the difference in Abbe numbers between the positive lens and the negative lens constituting the positive front group GP does not become too small, the refractive power of each lens constituting the positive front group GP does not become too strong. As a result, it becomes easy to correct high-order spherical aberration at the telephoto end. 1.94<Nn+0.01×νn<2.5 (24)

[0144] In order to obtain better characteristics, the lower limit of conditional expression (24) should preferably be set to 2, and more preferably to 2.1. In order to obtain even better characteristics, the upper limit of conditional expression (24) should preferably be set to 2.35, and more preferably to 2.3.

[0145] In a configuration in which the positive front group GP includes a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive lens having a convex shape facing the object side are cemented in this order from the object side to the image side, it is preferable that the variable magnification optical system satisfy the following conditional expression (25). Here, the refractive index of the positive lens in the cemented lens with respect to the d-line is Np. The Abbe number of the positive lens in the cemented lens with respect to the d-line is νp. By ensuring that the corresponding value of conditional expression (25) is not equal to or less than the lower limit, it is possible to select materials other than those with low refractive indexes and low Abbe numbers, thereby suppressing an increase in high-order aberrations in spherical aberration at the telephoto end, and thereby facilitating high performance. Alternatively, it is possible to suppress undercorrection of longitudinal chromatic aberration at the telephoto end. By ensuring that the corresponding value of conditional expression (25) is not equal to or greater than the upper limit, it is possible to select materials other than those with high refractive indexes and high Abbe numbers, thereby enabling the selection of materials with a low specific gravity, and thereby facilitating weight reduction. Alternatively, it is possible to suppress overcorrection of longitudinal chromatic aberration at the telephoto end. 2<Np+0.01×νp<2.6 (25)

[0146] In order to obtain even better characteristics, the lower limit of conditional expression (25) should preferably be set to 2.15, and even more preferably to 2.25, and the upper limit of conditional expression (25) should preferably be set to 2.45, and even more preferably to 2.4.

[0147] When the average value of the Abbe numbers of all the positive lenses included in the positive front group GP based on the d-line is taken as νPpave, it is preferable that the variable magnification optical system satisfies the following conditional expression (26). By ensuring that the corresponding value of conditional expression (26) is not equal to or less than the lower limit, it is advantageous for correction of axial chromatic aberration, particularly at the telephoto end. By ensuring that the corresponding value of conditional expression (26) is not equal to or greater than the upper limit, it is advantageous for correction of various aberrations other than chromatic aberration. 35<νPpave<96 (26)

[0148] In order to obtain better characteristics, the lower limit of conditional expression (26) should more preferably be set to 42, even more preferably to 55, and even more preferably to 60. In order to obtain even better characteristics, the upper limit of conditional expression (26) should more preferably be set to 90, even more preferably to 82, and even more preferably to 75.

[0149] It is preferable that the variable magnification optical system satisfy the following conditional expression (27). Here, DEIw is the sum of the distance on the optical axis from the lens surface of the final lens group GE closest to the object to the lens surface of the final lens group GE closest to the image when focused on an object at infinity at the wide-angle end, and Bfw. For example, in the variable magnification optical system of FIG. 1, DEIw is the distance on the optical axis from the surface of the final lens group GE closest to the object to the image plane Sim. As an example, FIG. 2 shows the above distance DEIw. By ensuring that the corresponding value of conditional expression (27) is not equal to or less than the lower limit, it is possible to prevent the thickness of the final lens group GE on the optical axis from becoming too small, which is advantageous for correcting various aberrations in the final lens group GE. By ensuring that the corresponding value of conditional expression (27) is not equal to or greater than the upper limit, it is advantageous for shortening the overall optical length. 0.1<DEIw / TLw<0.5 (27)

[0150] In order to obtain better characteristics, the lower limit of conditional expression (27) should preferably be set to 0.15, more preferably 0.2, even more preferably 0.225, and even more preferably 0.25. In order to obtain better characteristics, the upper limit of conditional expression (27) should preferably be set to 0.45, more preferably 0.4, even more preferably 0.375, and even more preferably 0.35.

[0151] In a configuration in which the final lens group GE includes two or more lenses, it is preferable that at least two lenses in the final lens group GE satisfy the following conditional expression (28). Here, NE is the refractive index of the lenses included in the final lens group GE with respect to the d-line. νE is the Abbe number of the lenses included in the final lens group GE based on the d-line. It is preferable that NE and νE that satisfy conditional expression (28) use the same lens value. By ensuring that the corresponding value of conditional expression (28) is not equal to or less than the lower limit, it is possible to select materials other than those with low refractive indexes and low Abbe numbers, which makes it easier to correct chromatic aberration of magnification. By ensuring that the corresponding value of conditional expression (28) is not equal to or greater than the upper limit, it is possible to select materials other than those with high refractive indexes and high Abbe numbers, which makes it easier to select materials that do not have a large specific gravity, which makes it easier to reduce the weight. 1.85<NE+0.01×νE<2.14 (28)

[0152] In order to obtain better characteristics, the lower limit of conditional expression (28) should preferably be set to 1.92, more preferably to 1.97, and even more preferably to 2. In order to obtain even better characteristics, the upper limit of conditional expression (28) should preferably be set to 2.13, more preferably to 2.12, and even more preferably to 2.11.

[0153] 1, the intermediate group GM may be configured to include, in order from the object side to the image side, at least a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power. By including at least one lens group having positive refractive power and one lens group having negative refractive power in the intermediate group GM in this way, it becomes easier to suppress aberration fluctuations during magnification variation.

[0154] In a configuration in which the intermediate group GM includes, in succession from the object side to the image side, at least a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power, it is preferable that the variable magnification optical system satisfy the following conditional expression (29). Here, the focal length of the first intermediate lens group GM1 is defined as fM1. The focal length of the second intermediate lens group GM2 is defined as fM2. By ensuring that the corresponding value of conditional expression (29) is not equal to or less than the lower limit, the refractive power of the second intermediate lens group GM2 does not become too weak, which is advantageous for suppressing aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (29) is not equal to or greater than the upper limit, the refractive power of the first intermediate lens group GM1 does not become too weak, which is advantageous for suppressing spherical aberration at the telephoto end. 0.05<fM1 / (-fM2)<1.5 (29)

[0155] In order to obtain better characteristics, the lower limit of conditional expression (29) should preferably be set to 0.1, more preferably 0.14, even more preferably 0.16, even more preferably 0.18, and even more preferably 0.2. In order to obtain better characteristics, the upper limit of conditional expression (29) should preferably be set to 1, more preferably 0.8, even more preferably 0.7, even more preferably 0.6, and even more preferably 0.5.

[0156] However, in the variable magnification optical system of the present disclosure, the number and configuration of lens groups included in the intermediate group GM may differ from the example of Fig. 1. For example, the intermediate group GM of the present disclosure may be configured as follows.

[0157] The intermediate group GM may be configured to include, in succession from the object side to the image side, at least a first intermediate lens group having positive refractive power, a second intermediate lens group having negative refractive power, and a third intermediate lens group having positive refractive power. By including at least three lens groups in the intermediate group GM in this way, it becomes easier to suppress aberration fluctuations during zooming.

[0158] In a configuration in which the intermediate group GM includes, in succession from the object side to the image side, at least a first intermediate lens group having positive refractive power, a second intermediate lens group having negative refractive power, and a third intermediate lens group having positive refractive power, it is preferable that the variable magnification optical system satisfy at least one of the above conditional expression (29) and the following conditional expression (30):

[0159] In conditional expression (30), the focal length of the second intermediate lens group is fM2. The focal length of the third intermediate lens group is fM3. By ensuring that the corresponding value of conditional expression (30) is not equal to or less than the lower limit, the refractive power of the third intermediate lens group does not become too weak, which is advantageous for suppressing aberration fluctuations during zooming. By ensuring that the corresponding value of conditional expression (30) is not equal to or greater than the upper limit, the refractive power of the second intermediate lens group does not become too weak, which is advantageous for suppressing aberration fluctuations during zooming. 0.1<(-fM2 / fM3)<4 (30)

[0160] In order to obtain better characteristics, the lower limit of conditional expression (30) should more preferably be set to 0.4, even more preferably to 0.6, even more preferably to 0.8, even more preferably to 1, and even more preferably to 1.2. In order to obtain better characteristics, the upper limit of conditional expression (30) should more preferably be set to 3.5, even more preferably to 3, even more preferably to 2.5, even more preferably to 2.3, and even more preferably to 2.2.

[0161] The intermediate group GM may be configured to include, in order from the object side to the image side, a first intermediate lens group having positive refractive power and a second intermediate lens group having positive refractive power. By limiting the number of lens groups in the intermediate group GM to two in this way, it becomes easier to shorten the overall optical length.

[0162] When the intermediate group GM is configured to include, in order from the object side to the image side, a first intermediate lens group having positive refractive power and a second intermediate lens group having positive refractive power, it is preferable that the variable magnification optical system satisfy the following conditional expression (31). Here, the focal length of the first intermediate lens group is defined as fM1. The focal length of the second intermediate lens group is defined as fM2. By ensuring that the corresponding value of conditional expression (31) is not equal to or less than the lower limit, the refractive power of the second intermediate lens group does not become too weak, which is advantageous for correcting spherical aberration at the telephoto end. By ensuring that the corresponding value of conditional expression (31) is not equal to or greater than the upper limit, the refractive power of the first intermediate lens group does not become too weak, which is advantageous for suppressing aberration fluctuations during magnification. 0.05<fM1 / fM2<2 (31)

[0163] In order to obtain better characteristics, the lower limit of conditional expression (31) should preferably be 0.1, more preferably 0.12, even more preferably 0.14, even more preferably 0.16, and even more preferably 0.18. In order to obtain better characteristics, the upper limit of conditional expression (31) should preferably be 1.2, more preferably 0.6, even more preferably 0.5, even more preferably 0.4, and even more preferably 0.3.

[0164] The intermediate group GM may be configured to include, in order from the object side to the image side, at least a first intermediate lens group having positive refractive power, a second intermediate lens group having positive refractive power, and a third intermediate lens group having negative refractive power. By including at least three lens groups in this way, it becomes easier to suppress aberration fluctuations during zooming.

[0165] In a configuration in which the intermediate group GM includes, in succession from the object side to the image side, at least a first intermediate lens group having positive refractive power, a second intermediate lens group having positive refractive power, and a third intermediate lens group having negative refractive power, it is preferable that the variable magnification optical system satisfy the following conditional expression (30A). Here, the focal length of the second intermediate lens group is defined as fM2. The focal length of the third intermediate lens group is defined as fM3. By ensuring that the corresponding value of conditional expression (30A) is not equal to or less than the lower limit, the refractive power of the third intermediate lens group does not become too weak, which is advantageous for suppressing aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (30A) is not equal to or greater than the upper limit, the refractive power of the second intermediate lens group does not become too weak, which is advantageous for suppressing spherical aberration at the telephoto end. 0.1<(-fM2 / fM3)<4 (30A)

[0166] In order to obtain better characteristics, the lower limit of conditional formula (30A) should more preferably be set to 0.4, even more preferably to 0.6, even more preferably to 0.8, even more preferably to 1, and even more preferably to 1.2. In order to obtain even better characteristics, the upper limit of conditional formula (30A) should more preferably be set to 3.5, even more preferably to 3, even more preferably to 2.5, even more preferably to 2.3, and even more preferably to 2.2.

[0167] The intermediate group GM may be configured to include, in order from the object side to the image side, at least a first intermediate lens group having positive refractive power, a second intermediate lens group having positive refractive power, and a third intermediate lens group having positive refractive power. By including at least three lens groups in this way, it becomes easier to suppress aberration fluctuations during zooming.

[0168] In a configuration in which the intermediate group GM includes, in succession from the object side to the image side, at least a first intermediate lens group having positive refractive power, a second intermediate lens group having positive refractive power, and a third intermediate lens group having positive refractive power, it is preferable that the variable magnification optical system satisfy at least one of the following conditional expressions (31A) and (32). Here, the focal length of the first intermediate lens group is defined as fM1. The focal length of the second intermediate lens group is defined as fM2. The focal length of the third intermediate lens group is defined as fM3. 0.02<fM1 / fM2<0.7 (31A) 0.3<fM2 / fM3<4.5 (32)

[0169] By ensuring that the corresponding value of conditional expression (31A) is not equal to or less than the lower limit, the refractive power of the second intermediate lens group does not become too weak, which is advantageous for correcting spherical aberration at the telephoto end.By ensuring that the corresponding value of conditional expression (31A) is not equal to or greater than the upper limit, the refractive power of the first intermediate lens group does not become too weak, which is advantageous for suppressing aberration fluctuations during zooming.

[0170] In order to obtain better characteristics, the lower limit of conditional formula (31A) should preferably be set to 0.04, more preferably 0.06, even more preferably 0.08, even more preferably 0.1, and even more preferably 0.12. In order to obtain better characteristics, the upper limit of conditional formula (31A) should preferably be set to 0.55, even more preferably 0.45, even more preferably 0.35, even more preferably 0.3, and even more preferably 0.25.

[0171] By ensuring that the corresponding value of conditional expression (32) is not equal to or less than the lower limit, the positive refractive power of the third intermediate lens group does not become too weak, which is advantageous for correcting spherical aberration at the telephoto end.By ensuring that the corresponding value of conditional expression (32) is not equal to or greater than the upper limit, the positive refractive power of the second intermediate lens group does not become too weak, which is advantageous for suppressing aberration fluctuations during zooming.

[0172] In order to obtain better characteristics, the lower limit of conditional expression (32) should preferably be set to 0.4, more preferably 0.5, even more preferably 0.6, even more preferably 0.7, and even more preferably 0.8. In order to obtain better characteristics, the upper limit of conditional expression (32) should preferably be set to 3.5, even more preferably 3, even more preferably 2.5, even more preferably 2.25, and even more preferably 2.

[0173] The intermediate group GM may be configured to include, in order from the object side to the image side, a first intermediate lens group having positive refractive power, a second intermediate lens group having positive refractive power, a third intermediate lens group having positive refractive power, and a fourth intermediate lens group having positive refractive power. By including four lens groups in this manner, it becomes easier to suppress aberration fluctuations during zooming.

[0174] In a configuration in which the intermediate group GM consists of, in order from the object side to the image side, a first intermediate lens group having positive refractive power, a second intermediate lens group having positive refractive power, a third intermediate lens group having positive refractive power, and a fourth intermediate lens group having positive refractive power, it is preferable that the variable magnification optical system satisfies at least one of the above conditional expressions (31A) and (32) and the following conditional expression (33):

[0175] In conditional expression (33), the focal length of the third intermediate lens group is fM3. The focal length of the fourth intermediate lens group is fM4. By ensuring that the corresponding value of conditional expression (33) is not equal to or less than the lower limit, the refractive power of the fourth intermediate lens group does not become too weak, which is advantageous for correcting aberrations during zooming. By ensuring that the corresponding value of conditional expression (33) is not equal to or greater than the upper limit, the refractive power of the third intermediate lens group does not become too weak, which is advantageous for correcting spherical aberrations at the telephoto end. 0.3<fM3 / fM4<2.5 (33)

[0176] In order to obtain better characteristics, the lower limit of conditional expression (33) should preferably be set to 0.4, more preferably 0.45, even more preferably 0.5, even more preferably 0.55, and even more preferably 0.6. In order to obtain better characteristics, the upper limit of conditional expression (33) should preferably be set to 1.9, more preferably 1.7, even more preferably 1.5, even more preferably 1.4, and even more preferably 1.3.

[0177] Note that the example shown in Fig. 1 is just one example, and the variable magnification optical system of the present disclosure can be modified in various ways without departing from the spirit and scope of the technology of the present disclosure. For example, the number of lenses included in each lens group and focusing group may be different from that in the example of Fig. 1. Also, while Fig. 1 shows an example in which the variable magnification optical system is a zoom lens, the variable magnification optical system of the present disclosure may be a varifocal lens.

[0178] Specifically, for example, the positive front group GP may be configured to consist of a set of cemented lenses, or may be configured to consist of a single lens. This is advantageous for size reduction. Note that "single lens" means a single lens that is not cemented. The positive front group GP may be configured to consist of a set of cemented lenses in which a negative lens and a positive lens are cemented together, and a single lens with positive refractive power. This is advantageous for suppressing spherical aberration.

[0179] The lens unit closest to the object in the positive front group GP may move during zooming. This is advantageous for suppressing aberration fluctuations during zooming. The lens unit closest to the object in the positive front group GP may be fixed with respect to the image plane Sim during zooming. This is advantageous for suppressing fluctuations in the center of gravity during zooming.

[0180] The focusing group may be configured to consist of a single negative lens. This is advantageous for achieving compactness and weight reduction. The focusing group may be configured to consist of a pair of cemented lenses in which a negative lens and a positive lens are cemented together. This is advantageous for suppressing fluctuations in chromatic aberration during focusing. The focusing group may be configured to consist of a single lens group. This can contribute to simplifying the drive mechanism.

[0181] The final lens group GE may move during zooming. This is advantageous for suppressing aberration fluctuations during zooming. The final lens group GE may be fixed relative to the image plane Sim during zooming. This contributes to simplifying the drive mechanism.

[0182] The variable magnification optical system may be configured to include an image stabilization group that moves in a direction intersecting the optical axis Z during image blur correction. Image blur correction is performed by the movement of the image stabilization group. The image stabilization group may be configured to be located closer to the object than the focusing group.

[0183] The above-described preferred and possible configurations can be arbitrarily combined within a range that does not cause a contradiction, and it is preferable that they be selectively adopted as appropriate according to the required specifications.

[0184] As an example, one preferred aspect of the variable magnification optical system of the present disclosure comprises, in order from the object side to the image side, a positive front group GP consisting of two or less lens groups each having positive refractive power and having positive refractive power as a whole, a negative front group GN consisting of two or less lens groups each having negative refractive power and having negative refractive power as a whole, an intermediate group GM including one or more lens groups, and a final lens group GE, wherein all of the intervals between adjacent lens groups change during variable magnification, the lens group closest to the object of the intermediate group GM is a first intermediate lens group having positive refractive power, and includes at least one lens surface having a pole point on the image side of the positive front group GP, the pole point being a point on the lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis Z perpendicularly, and the above conditional expression (1) is satisfied.

[0185] Next, examples of the variable magnification optical system of the present disclosure will be described with reference to the drawings. Note that the reference symbols assigned to each group in the cross-sectional views of each example are used independently for each example to avoid cluttering the explanation and drawings due to an increase in the number of digits in the reference symbols. Therefore, even if common reference symbols are assigned in drawings of different examples, this does not necessarily mean that the configuration is the same.

[0186] [Example 1] The configuration and movement locus of the variable magnification optical system of Example 1 are shown in Figure 1. The illustration method and configuration are as described above, so some overlapping explanations will be omitted here. The variable magnification optical system of Example 1 comprises, in order from the object side to the image side, a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The intermediate group GM comprises, in order from the object side to the image side, two lens groups: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power. The focusing group comprises the second intermediate lens group GM2. When varying magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups.

[0187] For the variable magnification optical system of Example 1, basic lens data is shown in Tables 1A and 1B, specifications and variable surface spacing are shown in Table 2, and aspherical coefficients are shown in Tables 3A, 3B, and 3C. The tables of basic lens data and aspherical coefficients are shown in multiple tables to avoid making each table too long.

[0188] The table of basic lens data is written as follows. The "Sn" column shows the surface numbers, with the surface closest to the object being surface number 1 and the numbers increasing by one as you move toward the image side. The "R" column shows the radius of curvature of each surface. The "D" column shows the surface spacing on the optical axis between each surface and its adjacent surface on the image side. The "Nd" column shows the refractive index of each lens with respect to the d-line. The "νd" column shows the Abbe number of each lens based on the d-line.

[0189] The "Material" column in the tables of basic lens data, including the tables of the Examples described below, is written as follows: In the "Material" column, for lenses made of resin, "Plastic" is written, and for lenses made of a material other than resin, the name of the material is written before the " / " and the name of the manufacturer after the " / ". In the tables, the names of manufacturers are shown generally as follows: "OHARA" stands for Ohara Corporation. "HOYA" stands for Hoya Corporation. "CDGM" stands for Chengdu Guangming Optoelectronics Co., Ltd. "NHG" stands for Hubei Xinhuaguang Information Materials Co., Ltd.

[0190] The "ED" column indicates the effective diameter of each surface. The "PD" column indicates the diameter of each circle centered on a point on the optical axis and passing through each pole. In other words, the "PD" column indicates a value twice the height of each pole from the optical axis. On the left side of the "Sn" column, the rows of lenses corresponding to the first aspherical lens, the second aspherical lens, and the third aspherical lens are labeled "La1," "La2," and "La3," respectively.

[0191] In the table of basic lens data, the sign of the radius of curvature of a surface with a convex shape facing the object side is positive, and the sign of the radius of curvature of a surface with a convex shape facing the image side is negative. In Table 1, the column for the surface number of the surface corresponding to the aperture stop St is filled in with the surface number and the term (St). The value in the bottom column of the D column in the table is the distance between the surface closest to the image side in the table and the image plane Sim. The symbol DD[ ] is used to indicate the variable surface distance during magnification, and the surface number of this distance on the object side is entered in the [ ] in the surface distance column.

[0192] Table 2 shows the zoom ratio Zr, focal length f, back focus Bf, maximum F-number FNo., maximum full angle of view 2ω, and variable surface spacing based on the d-line. When the variable magnification optical system is a zoom lens, the zoom ratio is synonymous with the zoom magnification. The [°] in the 2ω column indicates that the unit is degrees. In Table 2, the columns labeled "Wide," "Middle," and "Tele" show the values ​​for the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively.

[0193] In the basic lens data, the surface numbers of aspherical surfaces are marked with an asterisk (*), and the value of the paraxial radius of curvature is entered in the column for the radius of curvature of the aspherical surface. In Table 3, the Sn row indicates the surface numbers of the aspherical surfaces, and the KA and Am rows indicate the numerical values ​​of the aspherical coefficients for each aspherical surface. Note that m in Am is an integer of 3 or more, and varies depending on the surface. For example, for the third surface in Example 1, m = 3, 4, 5, ..., 20. The numerical values ​​of the aspherical coefficients in Table 3, "E±n" (n: integer), are expressed as "×10 ±ｎ " KA and Am are aspherical coefficients in the aspherical formula expressed as follows: Zd = C × h ２ / {1 + (1 - KA × C ２ ×h ２ ) １ / ２} + ΣAm × h ｍ where Zd: aspherical depth (length of perpendicular line dropped from a point on the aspherical surface at height h to a plane perpendicular to the optical axis Z where the aspherical vertex is in contact) h: height (distance from the optical axis Z to the lens surface) C: reciprocal of the paraxial radius of curvature KA, Am: aspherical coefficients, and Σ in the aspherical formula represents the summation over m.

[0194] In the data in each table, degrees are used as the unit of angle and millimeters as the unit of length, but since the optical system can be used with proportional magnification or reduction, other appropriate units can also be used. Also, in each table below, values ​​are listed rounded to a predetermined number of decimal places.

[0195]

[0196]

[0197]

[0198]

[0199]

[0200]

[0201] FIG. 6 shows aberration diagrams of the variable magnification optical system of Example 1 when focused on an object at infinity. From left to right, FIG. 6 shows spherical aberration, astigmatism, distortion, and lateral chromatic aberration. In FIG. 6, the upper row labeled "Wide" shows aberrations at the wide-angle end, the middle row labeled "Middle" shows aberrations at the intermediate focal length, and the lower row labeled "Tele" shows aberrations at the telephoto end. In the spherical aberration diagram, aberrations at the d-line, C-line, and F-line are shown by solid lines, long-dashed lines, and short-dashed lines, respectively. In the astigmatism diagram, aberrations at the d-line in the sagittal direction are shown by solid lines, and aberrations at the d-line in the tangential direction are shown by short-dashed lines. In the distortion diagram, aberrations at the d-line are shown by solid lines. In the lateral chromatic aberration diagram, aberrations at the C-line and F-line are shown by long-dashed lines and short-dashed lines, respectively. In the spherical aberration diagram, the maximum F-number is shown after FNo. =. In the other aberration diagrams, the maximum half angle of view is shown after ω =.

[0202] The symbols, meanings, notation methods, and illustration methods of each data item related to the above-mentioned first embodiment are basically the same in the following embodiments unless otherwise specified, and therefore, redundant explanations will be omitted below.

[0203] [Example 2] The configuration and movement locus of the variable magnification optical system of Example 2 are shown in Figure 7. The variable magnification optical system of Example 2 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0204] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0205] For the variable magnification optical system of Example 2, basic lens data is shown in Tables 4A and 4B, specifications and variable surface spacing are shown in Table 5, aspherical coefficients are shown in Tables 6A, 6B, and 6C, and aberration diagrams are shown in FIG. 8.

[0206]

[0207]

[0208]

[0209]

[0210]

[0211]

[0212] [Example 3] The configuration and movement locus of the variable magnification optical system of Example 3 are shown in Figure 9. The variable magnification optical system of Example 3 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power.

[0213] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0214] For the variable magnification optical system of Example 3, basic lens data is shown in Tables 7A and 7B, specifications and variable surface spacing are shown in Table 8, aspherical coefficients are shown in Tables 9A, 9B, and 9C, and aberration diagrams are shown in FIG. 10.

[0215]

[0216]

[0217]

[0218]

[0219]

[0220]

[0221] [Example 4] The configuration and movement locus of the variable magnification optical system of Example 4 are shown in Figure 11. The variable magnification optical system of Example 4 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side, a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power.

[0222] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0223] For the variable magnification optical system of Example 4, basic lens data is shown in Tables 10A and 10B, specifications and variable surface spacing are shown in Table 11, aspherical coefficients are shown in Tables 12A, 12B, 12C, and 12D, and respective aberration diagrams are shown in FIG.

[0224]

[0225]

[0226]

[0227]

[0228]

[0229]

[0230]

[0231] [Example 5] The configuration and movement locus of the variable magnification optical system of Example 5 are shown in Figure 13. The variable magnification optical system of Example 5 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power.

[0232] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0233] For the variable magnification optical system of Example 5, basic lens data is shown in Tables 13A and 13B, specifications and variable surface spacing are shown in Table 14, aspherical coefficients are shown in Tables 15A, 15B, and 15C, and aberration diagrams are shown in FIG. 14.

[0234]

[0235]

[0236]

[0237]

[0238]

[0239]

[0240] [Example 6] The configuration and movement locus of the variable magnification optical system of Example 6 are shown in Figure 15. The variable magnification optical system of Example 6 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power.

[0241] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0242] For the variable magnification optical system of Example 6, basic lens data is shown in Tables 16A and 16B, specifications and variable surface spacing are shown in Table 17, aspherical coefficients are shown in Tables 18A, 18B, and 18C, and aberration diagrams are shown in FIG. 16.

[0243]

[0244]

[0245]

[0246]

[0247]

[0248]

[0249] [Example 7] The configuration and movement locus of the variable magnification optical system of Example 7 are shown in Figure 17. The variable magnification optical system of Example 7 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power.

[0250] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0251] For the variable magnification optical system of Example 7, basic lens data is shown in Tables 19A and 19B, specifications and variable surface spacing are shown in Table 20, aspherical coefficients are shown in Tables 21A, 21B, and 21C, and respective aberration diagrams are shown in FIG. 18.

[0252]

[0253]

[0254]

[0255]

[0256]

[0257]

[0258] [Embodiment 8] The configuration and movement locus of the variable magnification optical system of Example 8 are shown in Figure 19. The variable magnification optical system of Example 8 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power, in order from the object side to the image side.

[0259] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0260] For the variable magnification optical system of Example 8, basic lens data is shown in Tables 22A and 22B, specifications and variable surface spacing are shown in Table 23, aspherical coefficients are shown in Tables 24A, 24B, and 24C, and respective aberration diagrams are shown in FIG. 20.

[0261]

[0262]

[0263]

[0264]

[0265]

[0266]

[0267] [Example 9] The configuration and movement locus of the variable magnification optical system of Example 9 are shown in Figure 21. The variable magnification optical system of Example 9 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM having positive refractive power, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of one lens group, which is a first intermediate lens group GM1 having positive refractive power.

[0268] When varying magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of a cemented lens formed by cementing together the lens closest to the image in the intermediate group GM and the second lens from the image side in the intermediate group GM. When focusing from an object at infinity to a closest object, the focusing group moves toward the image side.

[0269] For the variable magnification optical system of Example 9, basic lens data is shown in Tables 25A and 25B, specifications and variable surface spacing are shown in Table 26, aspherical coefficients are shown in Tables 27A, 27B, and 27C, and respective aberration diagrams are shown in FIG. 22.

[0270]

[0271]

[0272]

[0273]

[0274]

[0275]

[0276] [Example 10] The configuration and movement locus of the variable magnification optical system of Example 10 are shown in Figure 23. The variable magnification optical system of Example 10 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM having positive refractive power, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of one lens group, which is a first intermediate lens group GM1 having positive refractive power.

[0277] When varying magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of a cemented lens formed by cementing together the lens closest to the image in the intermediate group GM and the second lens from the image side in the intermediate group GM. When focusing from an object at infinity to a closest object, the focusing group moves toward the image side.

[0278] For the variable magnification optical system of Example 10, basic lens data is shown in Tables 28A and 28B, specifications and variable surface spacing are shown in Table 29, aspherical coefficients are shown in Tables 30A, 30B, and 30C, and respective aberration diagrams are shown in FIG. 24.

[0279]

[0280]

[0281]

[0282]

[0283]

[0284]

[0285] [Example 11] The configuration and movement locus of the variable magnification optical system of Example 11 are shown in Figure 25. The variable magnification optical system of Example 11 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power, in order from the object side to the image side.

[0286] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0287] For the variable magnification optical system of Example 11, basic lens data is shown in Tables 31A and 31B, specifications and variable surface spacing are shown in Table 32, aspherical coefficients are shown in Tables 33A, 33B, 33C, and 33D, and respective aberration diagrams are shown in FIG.

[0288]

[0289]

[0290]

[0291]

[0292]

[0293]

[0294]

[0295] [Example 12] The configuration and movement locus of the variable magnification optical system of Example 12 are shown in Figure 27. The variable magnification optical system of Example 12 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having negative refractive power, in order from the object side to the image side.

[0296] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0297] For the variable magnification optical system of Example 12, basic lens data is shown in Tables 34A and 34B, specifications and variable surface spacing are shown in Table 35, aspherical coefficients are shown in Tables 36A, 36B, 36C, and 36D, and respective aberration diagrams are shown in FIG.

[0298]

[0299]

[0300]

[0301]

[0302]

[0303]

[0304]

[0305] [Example 13] The configuration and movement locus of the variable magnification optical system of Example 13 are shown in Figure 29. The variable magnification optical system of Example 13 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power, in order from the object side to the image side.

[0306] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0307] For the variable magnification optical system of Example 13, basic lens data is shown in Tables 37A and 37B, specifications and variable surface spacing are shown in Table 38, aspherical coefficients are shown in Tables 39A, 39B, 39C, and 39D, and respective aberration diagrams are shown in FIG.

[0308]

[0309]

[0310]

[0311]

[0312]

[0313]

[0314]

[0315] [Example 14] The configuration and movement locus of the variable magnification optical system of Example 14 are shown in Figure 31. The variable magnification optical system of Example 14 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0316] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0317] For the variable magnification optical system of Example 14, basic lens data is shown in Tables 40A and 40B, specifications and variable surface spacing are shown in Table 41, aspherical coefficients are shown in Tables 42A, 42B, 42C, and 42D, and respective aberration diagrams are shown in FIG.

[0318]

[0319]

[0320]

[0321]

[0322]

[0323]

[0324]

[0325] [Example 15] The configuration and movement locus of the variable magnification optical system of Example 15 are shown in Figure 33. The variable magnification optical system of Example 15 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0326] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0327] For the variable magnification optical system of Example 15, basic lens data is shown in Tables 43A and 43B, specifications and variable surface spacing are shown in Table 44, aspherical coefficients are shown in Tables 45A, 45B, 45C, and 45D, and each aberration diagram is shown in FIG.

[0328]

[0329]

[0330]

[0331]

[0332]

[0333]

[0334]

[0335] [Example 16] The configuration and movement locus of the variable magnification optical system of Example 16 are shown in Figure 35. The variable magnification optical system of Example 16 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having positive refractive power.

[0336] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0337] For the variable magnification optical system of Example 16, basic lens data is shown in Tables 46A and 46B, specifications and variable surface spacing are shown in Table 47, aspherical coefficients are shown in Tables 48A, 48B, and 48C, and respective aberration diagrams are shown in FIG.

[0338]

[0339]

[0340]

[0341]

[0342]

[0343]

[0344] [Example 17] The configuration and movement locus of the variable magnification optical system of Example 17 are shown in Figure 37. The variable magnification optical system of Example 17 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having positive refractive power.

[0345] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0346] For the variable magnification optical system of Example 17, basic lens data is shown in Tables 49A and 49B, specifications and variable surface spacing are shown in Table 50, aspherical coefficients are shown in Tables 51A, 51B, and 51C, and respective aberration diagrams are shown in FIG.

[0347]

[0348]

[0349]

[0350]

[0351]

[0352]

[0353] [Example 18] The configuration and movement locus of the variable magnification optical system of Example 18 are shown in Figure 39. The variable magnification optical system of Example 18 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0354] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0355] For the variable magnification optical system of Example 18, basic lens data is shown in Tables 52A and 52B, specifications and variable surface spacing are shown in Table 53, aspherical coefficients are shown in Tables 54A, 54B, and 54C, and each aberration diagram is shown in FIG.

[0356]

[0357]

[0358]

[0359]

[0360]

[0361]

[0362] [Example 19] The configuration and movement locus of the variable magnification optical system of Example 19 are shown in Figure 41. The variable magnification optical system of Example 19 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0363] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0364] For the variable magnification optical system of Example 19, basic lens data is shown in Tables 55A and 55B, specifications and variable surface spacing are shown in Table 56, aspherical coefficients are shown in Tables 57A, 57B, and 57C, and respective aberration diagrams are shown in FIG.

[0365]

[0366]

[0367]

[0368]

[0369]

[0370]

[0371] [Example 20] The configuration and movement locus of the variable magnification optical system of Example 20 are shown in Figure 43. The variable magnification optical system of Example 20 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM having positive refractive power, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of one lens group, which is a first intermediate lens group GM1 having positive refractive power.

[0372] When changing magnification from the wide-angle end to the telephoto end, the positive front group GP and the final lens group GE are fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is composed of several lenses that are part of the final lens group GE. When focusing from an object at infinity to a closest object, the focusing group moves toward the image side. The image stabilization group is composed of three lenses, the first to third lenses from the image side of the negative front group GN. The parentheses and downward arrows attached to these three lenses in the lower diagram of Figure 43 indicate that these three lenses constitute the image stabilization group. Note that the image stabilization group functions throughout the entire magnification range, including the wide-angle end state, but in Figure 43, the arrow is only included in the lower diagram to avoid cluttering the diagram. This method of illustrating the image stabilization group is similar to other embodiments.

[0373] For the variable magnification optical system of Example 20, basic lens data is shown in Tables 58A and 58B, specifications and variable surface spacing are shown in Table 59, aspherical coefficients are shown in Tables 60A, 60B, 60C, and 60D, and respective aberration diagrams are shown in FIG.

[0374]

[0375]

[0376]

[0377]

[0378]

[0379]

[0380]

[0381] [Example 21] The configuration and movement locus of the variable magnification optical system of Example 21 are shown in Figure 45. The variable magnification optical system of Example 21 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having positive refractive power.

[0382] When varying magnification from the wide-angle end to the telephoto end, the positive front group GP and the final lens group GE are fixed relative to the image plane Sim, while the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of several lenses that are part of the final lens group GE. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side. The image stabilization group is made up of three lenses, the first to third from the image side of the negative front group GN.

[0383] For the variable magnification optical system of Example 21, basic lens data is shown in Tables 61A and 61B, specifications and variable surface spacing are shown in Table 62, aspherical coefficients are shown in Tables 63A, 63B, and 63C, and respective aberration diagrams are shown in FIG.

[0384]

[0385]

[0386]

[0387]

[0388]

[0389]

[0390] [Example 22] The configuration and movement locus of the variable magnification optical system of Example 22 are shown in Figure 47. The variable magnification optical system of Example 22 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, and a third intermediate lens group GM3 having negative refractive power, in order from the object side to the image side.

[0391] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group consists of the third intermediate lens group GM3. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side. The image stabilization group consists of the three lenses, the first to third from the image side of the negative front group GN.

[0392] For the variable magnification optical system of Example 22, basic lens data is shown in Tables 64A and 64B, specifications and variable surface spacing are shown in Table 65, aspherical coefficients are shown in Tables 66A and 66B, and respective aberration diagrams are shown in FIG.

[0393]

[0394]

[0395]

[0396]

[0397]

[0398] [Example 23] The configuration and movement locus of the variable magnification optical system of Example 23 are shown in Figure 49. The variable magnification optical system of Example 23 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, and a third intermediate lens group GM3 having negative refractive power, in order from the object side to the image side.

[0399] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group consists of the third intermediate lens group GM3. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side. The image stabilization group consists of the three lenses, the first to third from the image side of the negative front group GN.

[0400] For the variable magnification optical system of Example 23, basic lens data is shown in Tables 67A and 67B, specifications and variable surface spacing are shown in Table 68, aspherical coefficients are shown in Tables 69A and 69B, and aberration diagrams are shown in FIG. 50.

[0401]

[0402]

[0403]

[0404]

[0405]

[0406] [Example 24] The configuration and movement locus of the variable magnification optical system of Example 24 are shown in Figure 51. The variable magnification optical system of Example 24 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, and a third intermediate lens group GM3 having negative refractive power, in order from the object side to the image side.

[0407] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group consists of the third intermediate lens group GM3. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side. The image stabilization group consists of the three lenses, the first to third from the image side of the negative front group GN.

[0408] For the variable magnification optical system of Example 24, basic lens data is shown in Tables 70A and 70B, specifications and variable surface spacing are shown in Table 71, aspherical coefficients are shown in Tables 72A, 72B, and 72C, and respective aberration diagrams are shown in FIG.

[0409]

[0410]

[0411]

[0412]

[0413]

[0414]

[0415] [Example 25] The configuration and movement locus of the variable magnification optical system of Example 25 are shown in Figure 53. The variable magnification optical system of Example 25 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, and a third intermediate lens group GM3 having negative refractive power, in order from the object side to the image side.

[0416] When changing magnification from the wide-angle end to the telephoto end, all lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group consists of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side. The image stabilization group consists of two lenses, the third and fourth from the object side of the first intermediate lens group GM1.

[0417] For the variable magnification optical system of Example 25, basic lens data is shown in Tables 73A and 73B, specifications and variable surface spacing are shown in Table 74, aspherical coefficients are shown in Table 75, and various aberration diagrams are shown in FIG.

[0418]

[0419]

[0420]

[0421]

[0422] [Example 26] The configuration and movement locus of the variable magnification optical system of Example 26 are shown in Figure 55. The variable magnification optical system of Example 26 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of four lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, a third intermediate lens group GM3 having positive refractive power, and a fourth intermediate lens group GM4 having positive refractive power.

[0423] When changing magnification from the wide-angle end to the telephoto end, all lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The variable magnification optical system includes two focusing groups. The focusing group on the object side consists of the third intermediate lens group GM3, and the focusing group on the image side consists of the fourth intermediate lens group GM4. When focusing from an object at infinity to the closest object, these two focusing groups move toward the object side while changing the spacing between them. The image stabilization group consists of a single lens in the second intermediate lens group GM2 that is closest to the object.

[0424] For the variable magnification optical system of Example 26, basic lens data is shown in Tables 76A and 76B, specifications and variable surface spacing are shown in Table 77, aspherical coefficients are shown in Table 78, and various aberration diagrams are shown in FIG.

[0425]

[0426]

[0427]

[0428]

[0429] [Example 27] The configuration and movement locus of the variable magnification optical system of Example 27 are shown in Figure 57. The variable magnification optical system of Example 27 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of four lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, a third intermediate lens group GM3 having negative refractive power, and a fourth intermediate lens group GM4 having positive refractive power.

[0430] When changing magnification from the wide-angle end to the telephoto end, all lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group consists of the third intermediate lens group GM3. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side. The image stabilization group consists of a single lens in the second intermediate lens group GM2 that is closest to the object.

[0431] For the variable magnification optical system of Example 27, basic lens data is shown in Tables 79A and 79B, specifications and variable surface spacing are shown in Table 80, aspherical coefficients are shown in Table 81, and various aberration diagrams are shown in FIG.

[0432]

[0433]

[0434]

[0435]

[0436] [Example 28] The configuration and movement locus of the variable magnification optical system of Example 28 are shown in Figure 59. The variable magnification optical system of Example 28 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of four lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, a third intermediate lens group GM3 having positive refractive power, and a fourth intermediate lens group GM4 having positive refractive power.

[0437] When changing magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group is made up of the third intermediate lens group GM3. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0438] For the variable magnification optical system of Example 28, basic lens data is shown in Tables 82A and 82B, specifications and variable surface spacing are shown in Table 83, aspherical coefficients are shown in Tables 84A and 84B, and aberration diagrams are shown in FIG. 60.

[0439]

[0440]

[0441]

[0442]

[0443] [Example 29] The configuration and movement locus of the variable magnification optical system of Example 29 are shown in Figure 61. The variable magnification optical system of Example 29 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of four lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, a third intermediate lens group GM3 having positive refractive power, and a fourth intermediate lens group GM4 having positive refractive power.

[0444] When changing magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group is made up of the third intermediate lens group GM3. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0445] For the variable magnification optical system of Example 29, basic lens data is shown in Tables 85A and 85B, specifications and variable surface spacing are shown in Table 86, aspherical coefficients are shown in Table 87, and various aberration diagrams are shown in FIG.

[0446]

[0447]

[0448]

[0449]

[0450] [Example 30] The configuration and movement locus of the variable magnification optical system of Example 30 are shown in Figure 63. The variable magnification optical system of Example 30 consists of, in order from the object side to the image side, a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of a single lens group. The negative front group GN consists of two lens groups, in order from the object side to the image side: a first negative lens group GN1 having negative refractive power and a second negative lens group GN2 having negative refractive power. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power and a second intermediate lens group GM2 having positive refractive power.

[0451] When varying magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group is made up of the second negative lens group GN2. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0452] For the variable magnification optical system of Example 30, basic lens data is shown in Tables 88A and 88B, specifications and variable surface spacing are shown in Table 89, aspherical coefficients are shown in Table 90, and various aberration diagrams are shown in FIG.

[0453]

[0454]

[0455]

[0456]

[0457] [Example 31] The configuration and movement locus of the variable magnification optical system of Example 31 are shown in Figure 65. The variable magnification optical system of Example 31 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, and a third intermediate lens group GM3 having positive refractive power, in order from the object side to the image side.

[0458] When changing magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0459] For the variable magnification optical system of Example 31, basic lens data are shown in Tables 91A and 91B, specifications and variable surface spacing are shown in Table 92, aspherical coefficients are shown in Table 93, and various aberration diagrams are shown in FIG.

[0460]

[0461]

[0462]

[0463]

[0464] [Example 32] The configuration and movement locus of the variable magnification optical system of Example 32 are shown in Figure 67. The variable magnification optical system of Example 32 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists, in order from the object side to the image side, of two lens groups: a first positive lens group GP1 having positive refractive power and a second positive lens group GP2 having positive refractive power. The negative front group GN consists of one lens group. The intermediate group GM consists, in order from the object side to the image side, of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having positive refractive power, and a third intermediate lens group GM3 having positive refractive power.

[0465] When changing magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the object.

[0466] For the variable magnification optical system of Example 32, basic lens data is shown in Tables 94A and 94B, specifications and variable surface spacing are shown in Table 95, aspherical coefficients are shown in Table 96, and various aberration diagrams are shown in FIG.

[0467]

[0468]

[0469]

[0470]

[0471] [Example 33] The configuration and movement locus of the variable magnification optical system of Example 33 are shown in Figure 69. The variable magnification optical system of Example 33 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of three lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, and a third intermediate lens group GM3 having positive refractive power, in order from the object side to the image side.

[0472] When changing magnification from the wide-angle end to the telephoto end, all lens groups change the spacing between adjacent lens groups and move along the optical axis Z. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0473] For the variable magnification optical system of Example 33, basic lens data is shown in Tables 97A and 97B, specifications and variable surface spacing are shown in Table 98, aspherical coefficients are shown in Tables 99A and 99B, and aberration diagrams are shown in FIG.

[0474]

[0475]

[0476]

[0477]

[0478]

[0479] [Example 34] The configuration and movement locus of the variable magnification optical system of Example 34 are shown in Figure 71. The variable magnification optical system of Example 34 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0480] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0481] For the variable magnification optical system of Example 34, basic lens data is shown in Tables 100A and 100B, specifications and variable surface spacing are shown in Table 101, aspherical coefficients are shown in Tables 102A and 102B, and aberration diagrams are shown in FIG.

[0482]

[0483]

[0484]

[0485]

[0486]

[0487] [Example 35] The configuration and movement locus of the variable magnification optical system of Example 35 are shown in Figure 73. The variable magnification optical system of Example 35 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0488] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0489] For the variable magnification optical system of Example 35, basic lens data is shown in Tables 103A and 103B, specifications and variable surface spacing are shown in Table 104, aspherical coefficients are shown in Tables 105A and 105B, and aberration diagrams are shown in FIG.

[0490]

[0491]

[0492]

[0493]

[0494]

[0495] [Example 36] The configuration and movement locus of the variable magnification optical system of Example 36 are shown in Figure 75. The variable magnification optical system of Example 36 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having positive refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of two lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, and a second intermediate lens group GM2 having negative refractive power.

[0496] When changing magnification from the wide-angle end to the telephoto end, the final lens group GE is fixed with respect to the image plane Sim, and the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The focusing group is made up of the second intermediate lens group GM2. When focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0497] For the variable magnification optical system of Example 36, basic lens data is shown in Tables 106A and 106B, specifications and variable surface spacing are shown in Table 107, aspherical coefficients are shown in Tables 108A and 108B, and aberration diagrams are shown in FIG.

[0498]

[0499]

[0500]

[0501]

[0502]

[0503] [Example 37] The configuration and movement locus of the variable magnification optical system of Example 37 are shown in Figure 77. The variable magnification optical system of Example 37 consists of, in order from the object side to the image side, a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of two lens groups, in order from the object side to the image side: a first positive lens group GP1 having positive refractive power, and a second positive lens group GP2 having positive refractive power. The negative front group GN consists of a single lens group. The intermediate group GM consists of five lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, a third intermediate lens group GM3 having positive refractive power, a fourth intermediate lens group GM4 having negative refractive power, and a fifth intermediate lens group GM5 having positive refractive power.

[0504] When varying magnification from the wide-angle end to the telephoto end, the first positive lens group GP1, the third intermediate lens group GM3, and the final lens group GE are fixed with respect to the image plane Sim, while the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The variable magnification optical system includes two focusing groups. The object-side focusing group consists of the fourth intermediate lens group GM4, and the image-side focusing group consists of the fifth intermediate lens group GM5. When focusing from an object at infinity to the closest object, the object-side focusing group moves toward the image side, and the image-side focusing group moves toward the object side. The image stabilization group consists of the two lenses second and third from the image side of the third intermediate lens group GM3.

[0505] For the variable magnification optical system of Example 37, basic lens data is shown in Tables 109A and 109B, specifications and variable surface spacing are shown in Table 110, aspherical coefficients are shown in Tables 111A, 111B, and 111C, and respective aberration diagrams are shown in FIG.

[0506]

[0507]

[0508]

[0509]

[0510]

[0511]

[0512] [Example 38] The configuration and movement locus of the variable magnification optical system of Example 38 are shown in Figure 79. The variable magnification optical system of Example 38 consists of, in order from the object side to the image side, a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of two lens groups, in order from the object side to the image side, a first positive lens group GP1 having positive refractive power and a second positive lens group GP2 having positive refractive power. The negative front group GN consists of a single lens group. The intermediate group GM consists of five lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, a third intermediate lens group GM3 having positive refractive power, a fourth intermediate lens group GM4 having negative refractive power, and a fifth intermediate lens group GM5 having positive refractive power.

[0513] When varying magnification from the wide-angle end to the telephoto end, the first positive lens group GP1, the third intermediate lens group GM3, and the final lens group GE are fixed with respect to the image plane Sim, while the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The variable magnification optical system includes two focusing groups. The object-side focusing group consists of the fourth intermediate lens group GM4, and the image-side focusing group consists of the fifth intermediate lens group GM5. When focusing from an object at infinity to the closest object, the object-side focusing group moves toward the image side, and the image-side focusing group moves toward the object side. The image stabilization group consists of the two lenses second and third from the image side of the third intermediate lens group GM3.

[0514] For the variable magnification optical system of Example 38, basic lens data is shown in Tables 112A and 112B, specifications and variable surface spacing are shown in Table 113, aspherical coefficients are shown in Tables 114A, 114B, and 114C, and respective aberration diagrams are shown in FIG. 80.

[0515]

[0516]

[0517]

[0518]

[0519]

[0520]

[0521] [Example 39] The configuration and movement locus of the variable magnification optical system of Example 39 are shown in Figure 81. The variable magnification optical system of Example 39 consists, in order from the object side to the image side, of a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of one lens group. The intermediate group GM consists of five lens groups: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, a third intermediate lens group GM3 having positive refractive power, a fourth intermediate lens group GM4 having negative refractive power, and a fifth intermediate lens group GM5 having positive refractive power.

[0522] When varying magnification from the wide-angle end to the telephoto end, the positive front group GP, the third intermediate lens group GM3, and the final lens group GE are fixed with respect to the image plane Sim, while the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The variable magnification optical system includes two focusing groups. The object-side focusing group consists of the fourth intermediate lens group GM4, and the image-side focusing group consists of the fifth intermediate lens group GM5. When focusing from an object at infinity to the closest object, the object-side focusing group moves toward the image side, and the image-side focusing group moves toward the object side. The image stabilization group consists of the two lenses second and third from the image side of the third intermediate lens group GM3.

[0523] For the variable magnification optical system of Example 39, basic lens data is shown in Tables 115A and 115B, specifications and variable surface spacing are shown in Table 116, aspherical coefficients are shown in Tables 117A, 117B, and 117C, and respective aberration diagrams are shown in FIG. 82.

[0524]

[0525]

[0526]

[0527]

[0528]

[0529]

[0530] [Example 40] The configuration and movement locus of the variable magnification optical system of Example 40 are shown in Figure 83. The variable magnification optical system of Example 40 consists of, in order from the object side to the image side, a positive front group GP having positive refractive power, a negative front group GN having negative refractive power, an intermediate group GM, and a final lens group GE having negative refractive power. The positive front group GP consists of one lens group. The negative front group GN consists of two lens groups, in order from the object side to the image side, a first negative lens group GN1 having negative refractive power and a second negative lens group GN2 having negative refractive power. The intermediate group GM consists of five lens groups, in order from the object side to the image side: a first intermediate lens group GM1 having positive refractive power, a second intermediate lens group GM2 having negative refractive power, a third intermediate lens group GM3 having positive refractive power, a fourth intermediate lens group GM4 having negative refractive power, and a fifth intermediate lens group GM5 having positive refractive power.

[0531] When varying magnification from the wide-angle end to the telephoto end, the positive front group GP, the third intermediate lens group GM3, and the final lens group GE are fixed with respect to the image plane Sim, while the other lens groups move along the optical axis Z while changing the spacing between adjacent lens groups. The variable magnification optical system includes two focusing groups. The object-side focusing group consists of the fourth intermediate lens group GM4, and the image-side focusing group consists of the fifth intermediate lens group GM5. When focusing from an object at infinity to the closest object, the object-side focusing group moves toward the image side, and the image-side focusing group moves toward the object side. The image stabilization group consists of the two lenses second and third from the image side of the third intermediate lens group GM3.

[0532] For the variable magnification optical system of Example 40, basic lens data is shown in Tables 118A and 118B, specifications and variable surface spacing are shown in Table 119, aspherical coefficients are shown in Tables 120A, 120B, and 120C, and respective aberration diagrams are shown in FIG. 81.

[0533]

[0534]

[0535]

[0536]

[0537]

[0538]

[0539] Tables 121 to 129 show the corresponding values ​​of conditional expressions (1) to (33) for the variable magnification optical systems of Examples 1 to 40 described above. The corresponding value of conditional expression (28) is shown for each lens in the final lens group GE. The corresponding values ​​of the Examples shown in Tables 121 to 129 may be used as the upper or lower limits of the conditional expressions to set preferred ranges for the conditional expressions.

[0540]

[0541]

[0542]

[0543]

[0544]

[0545]

[0546]

[0547]

[0548]

[0549] The variable magnification optical systems of Examples 1 to 40 are compact, yet maintain high optical performance with various aberrations well corrected. Furthermore, the variable magnification optical systems of some Examples achieve a high variable magnification ratio of more than 4.5.

[0550] Next, an imaging device according to an embodiment of the present disclosure will be described. Fig. 85 and Fig. 86 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Fig. 85 shows a perspective view of the camera 30 as seen from the front side, and Fig. 86 shows a perspective view of the camera 30 as seen from the rear side. The camera 30 is a so-called mirrorless digital camera, to which an interchangeable lens 20 can be removably attached. The interchangeable lens 20 is configured to include a variable magnification optical system 1 according to an embodiment of the present disclosure housed in a lens barrel.

[0551] The camera 30 includes a camera body 31. A shutter button 32 and a power button 33 are provided on the top surface of the camera body 31. An operation unit 34, an operation unit 35, and a display unit 36 ​​are provided on the back surface of the camera body 31. The display unit 36 ​​can display a captured image and an image within the angle of view before the image was captured.

[0552] A photographic opening through which light from a subject enters is provided in the center of the front surface of the camera body 31. A mount 37 is provided at a position corresponding to the photographic opening, and the interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0553] An imaging element 38 is provided within the camera body 31. The imaging element 38 outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20. For example, a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) is used as the imaging element 38. A signal processing circuit (not shown) and a recording medium (not shown) are also provided within the camera body 31. The signal processing circuit processes the imaging signal output from the imaging element 38 to generate an image. The recording medium is used to record the generated image. The camera 30 can capture still images or videos by pressing the shutter button 32, and the image data obtained by this capture is recorded on the recording medium.

[0554] Although the technology of the present disclosure has been described above using embodiments and examples, the technology of the present disclosure is not limited to the above embodiments and examples and can be modified in various ways. For example, the radius of curvature, surface spacing, refractive index, Abbe number, aspherical coefficient, etc. of each lens are not limited to the values ​​shown in the above examples and can take other values.

[0555] Furthermore, the imaging device according to the embodiment of the present disclosure is not limited to the above example, and can take various forms, such as a camera other than a mirrorless type, a film camera, a video camera, and a security camera.

[0556] The following additional notes are provided regarding the above embodiments and examples. [Note 1] The optical system comprises, in order from the object side to the image side, a positive front group consisting of two or less lens groups each having positive refractive power and having positive refractive power as a whole, a negative front group consisting of two or less lens groups each having negative refractive power and having negative refractive power as a whole, an intermediate group including one or more lens groups, and a final lens group, wherein all intervals between adjacent lens groups change during zooming, at least one lens surface having a pole point is included on the image side of the positive front group, wherein the pole point is a point on a lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis perpendicularly, and the lens group closest to the object of the intermediate group is a first intermediate lens group having positive refractive power, where Bfw is the back focus at the air-equivalent distance of the entire system when focused on an object at infinity at the wide-angle end, fw is the focal length of the entire system when focused on an object at infinity at the wide-angle end, and ωw is the maximum half angle of view when focused on an object at infinity at the wide-angle end, A variable magnification optical system that satisfies the following conditional expression (1): 0.25<Bfw / (fw×tan ωw)<2 (1) [Supplementary Note 2] A variable magnification optical system according to Supplementary Note 1, that satisfies the following conditional expression (2): 2<TLw / (fw×tan ωw)<16 (2) where TLw is the sum of the on-optical axial distance from the lens surface of the positive front group that is closest to the object to the lens surface of the final lens group that is closest to the image when focused on an object at infinity at the wide-angle end. [Supplementary Note 3] A variable magnification optical system according to Supplementary Note 1 or Supplementary Note 2, which satisfies conditional expression (3) expressed by: 2.5<fPmax / fMmax<30 (3), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, and fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group. [Supplementary Note 4] A variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 3, which satisfies conditional expression (4) expressed by: 3.8<fPmax / (-fNmax)<40 (4), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, and fNmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the negative front group.[Appendix 5] A variable magnification optical system according to any one of Appendices 1 to 4, which satisfies conditional expression (5) expressed as follows: 0.15<FNot / (ft / fw)<1.6 (5), where FNot is the maximum F-number when focused on an object at infinity at the telephoto end, and ft is the focal length of the entire system when focused on an object at infinity at the telephoto end. [Appendix 6] A variable magnification optical system according to any one of Appendices 1 to 5, wherein the final lens group includes at least one lens surface having the pole point. [Appendix 7] The variable magnification optical system according to Appendices 6, wherein the final lens group includes two or more lenses including at least one lens surface having the pole point. [Appendix 8] The variable magnification optical system according to Appendices 7, wherein the final lens group includes three or more lenses including at least one lens surface having the pole point. [Supplementary Note 9] The variable magnification optical system according to any one of Supplementary Notes 1 to 8, wherein a focusing group that moves along the optical axis during focusing is disposed closest to the intermediate group to the image side. [Supplementary Note 10] The variable magnification optical system according to any one of Supplementary Notes 1 to 9, which satisfies conditional expression (6) expressed by: 0≦DEair / DGE<0.45 (6), where DEair is the sum of air spaces on the optical axis within the final lens group, and DGE is the distance on the optical axis from the lens surface of the final lens group closest to the object side to the lens surface of the final lens group closest to the image side. [Supplementary Note 11] A variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 10, which satisfies conditional expression (7) expressed as follows: 0.05<DGE / TLw<0.3 (7) [Supplementary Note 12] A variable magnification optical system according to Supplementary Note 11, which satisfies conditional expression (7-1) expressed as follows: 0.08<DGE / TLw<0.25 (7-1) [Supplementary Note 13] A variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 12, wherein the final lens group includes a lens having a convex shape facing the object side in a paraxial region and having at least one lens surface having the polar point.[Supplementary Note 14] The variable magnification optical system according to any one of Supplementary Notes 1 to 13, wherein the negative front group includes a first aspherical lens that has a concave shape toward the object side in the paraxial region and has an inflection point on its object-side lens surface, where the concave and convex shapes change midway as one moves from the optical axis to the periphery. [Supplementary Note 15] The variable magnification optical system according to any one of Supplementary Notes 1 to 14, wherein the negative front group includes a second aspherical lens that has a concave shape toward the image side in the paraxial region and has an inflection point on its image-side lens surface, where the concave and convex shapes change midway as one moves from the optical axis to the periphery. [Supplementary Note 16] The variable magnification optical system according to any one of Supplementary Notes 1 to 15, wherein the intermediate group includes a third aspherical lens that has a biconvex shape in the paraxial region and has an inflection point on its lens surface, where the concave and convex shapes change midway as one moves from the optical axis to the periphery. [Supplementary Note 17] The variable magnification optical system according to any one of Supplementary Notes 1 to 16, wherein the intermediate group includes a plurality of negative lenses. [Supplementary Note 18] A variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 17, wherein the positive front group includes a negative lens and a positive lens. [Supplementary Note 19] The variable magnification optical system according to Supplementary Note 14, which satisfies conditional expression (8) expressed by the following formula: -10<Ra1y / Ra1c<-0.05 (8) where Ra1y is the radius of curvature of the object-side surface of the first aspherical lens at the position of maximum effective diameter, and Ra1c is the paraxial radius of curvature of the object-side surface of the first aspherical lens. [Supplementary Note 20] A variable magnification optical system according to Supplementary Note 14 or Supplementary Note 19, wherein the lens arranged closest to the object side in the negative front group is the first aspherical lens. [Supplementary Note 21] A variable magnification optical system according to Supplementary Note 15, which satisfies conditional expression (9) expressed by the following formula: -1.5<Ra2y / Ra2c<0 (9) where Ra2y is the radius of curvature of the image-side surface of the second aspherical lens at the position of the maximum effective diameter, and Ra2c is the paraxial radius of curvature of the image-side surface of the second aspherical lens. [Supplementary Note 22] A variable magnification optical system according to Supplementary Note 15 or Supplementary Note 21, wherein the lens arranged closest to the image side in the negative front group is the second aspherical lens.[Supplementary Note 23] A variable magnification optical system according to Supplementary Note 16, wherein, of the third aspherical lenses included in the intermediate group, the object-side third aspherical lens arranged closest to the object side has at least one of the pole points on its image-side lens surface, and where, on the image-side lens surface of the object-side third aspherical lens, the smallest diameter of circles centered on a point on the optical axis and passing through each of the pole points is PDmin, and an effective diameter of the image-side surface of the object-side third aspherical lens is EDa3, satisfies conditional expression (10) expressed as follows: 0.45<PDmin / EDa3<0.95 (10) [Supplementary Note 24] A variable magnification optical system according to Supplementary Note 16 or Supplementary Note 23, wherein the lens arranged closest to the object side in the intermediate group is the object-side third aspherical lens. [Appendix 25] A variable magnification optical system according to any one of Appendices 1 to 24, which satisfies conditional expression (11) expressed by: 1.5<fPmax / (ft / FNot)<11 (11), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, ft is the focal length of the entire system in a state focused on an object at infinity at the telephoto end, and FNot is the maximum open F-number in a state focused on an object at infinity at the telephoto end. [Appendix 26] A variable magnification optical system according to any one of Appendices 1 to 25, which satisfies conditional expression (12) expressed by: 2<TLw / fw<15 (12), where TLw is the sum of the on-optical axial distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image in a state focused on an object at infinity at the wide-angle end. [Supplementary Note 27] A variable magnification optical system according to any one of Supplementary Notes 1 to 26, which satisfies the conditional expression (13) expressed by: 0.1<tan ωw / FNow<0.6 (13), where FNow is the maximum open F-number when focused on an object at infinity at the wide-angle end. [Supplementary Note 28] A variable magnification optical system according to any one of Supplementary Notes 1 to 27, which satisfies the conditional expression (14) expressed by: 0.05<fw / fPmax<1 (14), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group.[Supplementary Note 29] When the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group is fPmax, and the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, 1<fPmax / (fw×ft). １／２ <15 (15) [Appendix 30] The variable magnification optical system according to any one of Appendices 1 to 29, which satisfies conditional expression (16) expressed by: 0.7<TLw / ft<4 (16) where TLw is the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw, and ft is the focal length of the entire system when focused on an object at infinity at the telephoto end. [Appendix 31] The variable magnification optical system according to any one of Appendices 1 to 30, which satisfies conditional expression (17) expressed by: 2<ft / fw<10 (17) where ft is the focal length of the entire system when focused on an object at infinity at the telephoto end. [Supplementary Note 32] When the focal length of the lens unit having the strongest refractive power among the lens units included in the negative front group is fNmax, and the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, then 0.15<(-fNmax) / (fw×ft). １／２<1 (18) [Supplementary Note 33] The variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 32, which satisfies conditional expression (19) expressed by: 0.95<TLt / TLw<2 (19), where TLt is the sum of the on-optical axis distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image in a state focused on an object at infinity at the telephoto end, and the back focus in an air-equivalent distance of the entire system, and TLw is the sum of the on-optical axis distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image in a state focused on an object at infinity at the wide-angle end, and Bfw. [Appendix 34] A variable magnification optical system according to any one of Appendices 1 to 33, which satisfies the conditional expression (20) expressed by: -0.3<fw / fE<0.6 (20) where fE is the focal length of the final lens group. [Appendix 35] A variable magnification optical system according to any one of Appendices 1 to 34, which satisfies the conditional expression (21) expressed by: -0.4<ft / fE<1.5 (21) where ft is the focal length of the entire system when focused on an object at infinity at the telephoto end, and fE is the focal length of the final lens group. [Appendix 36] Of the lens groups included in the intermediate group, the focal length of the lens group having the strongest positive refractive power is fMmax, and ft is the focal length of the entire system when focused on an object at infinity at the telephoto end, 0.05<fMmax / (fw×ft) １／２<2 (22) The variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 35, which satisfies conditional expression (22) expressed by: 0.2<fw / fMmax<1.5 (23) [Supplementary Note 37] The variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 36, which satisfies conditional expression (23) expressed by: 0.2<fw / fMmax<1.5 (23) where fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group. [Supplementary Note 38] The variable magnification optical system according to any one of Supplementary Notes 1 to 37, wherein the positive front group includes a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive lens having a convex shape facing the object side are cemented together in this order from the object side to the image side, and wherein, where Nn is the refractive index of the negative meniscus lens of the cemented lens with respect to the d-line, and vn is the Abbe number of the negative meniscus lens of the cemented lens with reference to the d-line, the variable magnification optical system according to any one of Supplementary Notes 1 to 37 satisfies conditional expression (24) expressed by: 1.94<Nn+0.01×vn<2.5 (24) [Supplementary Note 39] The variable magnification optical system according to Supplementary Note 38, wherein, where Np is the refractive index of the positive lens of the cemented lens with reference to the d-line, and vp is the Abbe number of the positive lens of the cemented lens with reference to the d-line, the variable magnification optical system according to Supplementary Note 38 satisfies conditional expression (25) expressed by: 2<Np+0.01×vp<2.6 (25) [Appendix 40] A variable magnification optical system according to any one of Appendices 1 to 39, which satisfies conditional expression (26) expressed by: 35<νPpave<96 (26) where νPpave is the average value of the Abbe numbers based on the d-line of all positive lenses included in the positive front group. [Appendix 41] A variable magnification optical system according to any one of Appendices 1 to 40, which satisfies conditional expression (27) expressed by: 0.1<DEIw / TLw<0.5 (27) where DEIw is the sum of the optical axial distance from the lens surface of the final lens group closest to the object to the lens surface of the final lens group closest to the image in a state focused on an object at infinity at the wide-angle end and Bfw, and TLw is the sum of the optical axial distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image in a state focused on an object at infinity at the wide-angle end and Bfw.[Appendix 42] The variable magnification optical system according to any one of Appendices 1 to 41, wherein the final lens group includes two or more lenses, and where NE is the refractive index for the d-line of the lenses included in the final lens group and νE is the Abbe number based on the d-line of the lenses included in the final lens group, at least two lenses satisfy conditional expression (28) expressed by: 1.85<NE+0.01×νE<2.14 (28) [Appendix 43] The variable magnification optical system according to any one of Appendices 1 to 42, wherein the intermediate group includes one or two focusing groups that move along the optical axis during focusing. [Appendix 44] The variable magnification optical system according to any one of Appendices 1 to 43, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group and a second intermediate lens group having negative refractive power. [Appendix 45] The variable magnification optical system according to Appendix 44, which satisfies conditional expression (29) expressed by: 0.05<fM1 / (-fM2)<1.5 (29) where fM1 is the focal length of the first intermediate lens group and fM2 is the focal length of the second intermediate lens group. [Appendix 46] The variable magnification optical system according to any one of Appendix 1 to Appendix 45, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group, the second intermediate lens group, and a third intermediate lens group having positive refractive power. [Appendix 47] The variable magnification optical system according to Appendix 46, which satisfies conditional expression (30) expressed by: 0.1<(-fM2 / fM3)<4 (30) where fM2 is the focal length of the second intermediate lens group and fM3 is the focal length of the third intermediate lens group. [Supplementary Note 48] The variable magnification optical system according to any one of Supplementary Notes 1 to 43, wherein the intermediate group comprises, in order from the object side to the image side, the first intermediate lens group and a second intermediate lens group having positive refractive power. [Supplementary Note 49] The variable magnification optical system according to Supplementary Note 48, which satisfies conditional expression (31) expressed by: 0.05<fM1 / fM2<2 (31) where fM1 is the focal length of the first intermediate lens group and fM2 is the focal length of the second intermediate lens group. [Supplementary Note 50] The variable magnification optical system according to any one of Supplementary Notes 1 to 43, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group, a second intermediate lens group having positive refractive power, and a third intermediate lens group having negative refractive power.[Appendix 51] The variable magnification optical system according to Appendix 50, which satisfies conditional expression (30A) expressed by: 0.1<(-fM2 / fM3)<4 (30A) where the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3. [Appendix 52] The variable magnification optical system according to any one of Appendix 1 to Appendix 43, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group, a second intermediate lens group having positive refractive power, and a third intermediate lens group having positive refractive power. [Appendix 53] The variable magnification optical system according to Appendix 52, which satisfies conditional expression (31A) expressed by: 0.02<fM1 / fM2<0.7 (31A) where the focal length of the first intermediate lens group is fM1 and the focal length of the second intermediate lens group is fM2. [Appendix 54] The variable magnification optical system according to Appendix 52 or Appendix 53, which satisfies conditional expression (32) expressed by: 0.3<fM2 / fM3<4.5 (32) where the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3. [Appendix 55] The variable magnification optical system according to Appendix 53, wherein the intermediate group consists of, in order from the object side to the image side, the first intermediate lens group, the second intermediate lens group, the third intermediate lens group, and a fourth intermediate lens group having positive refractive power. [Appendix 56] The variable magnification optical system according to Appendix 55, which satisfies conditional expression (33) expressed by: 0.3<fM3 / fM4<2.5 (33) where the focal length of the third intermediate lens group is fM3 and the focal length of the fourth intermediate lens group is fM4. [Supplementary Note 57] An imaging device including the variable magnification optical system according to any one of Supplementary Note 1 to Supplementary Note 56.

[0557] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A lens system comprising, in order from the object side to the image side, a positive front group consisting of two or less lens groups each having positive refractive power and having positive refractive power as a whole, a negative front group consisting of two or less lens groups each having negative refractive power and having negative refractive power as a whole, an intermediate group including one or more lens groups, and a final lens group, wherein all intervals between adjacent lens groups change during zooming, at least one lens surface having a pole point is included on the image side of the positive front group, wherein the pole point is a point on a lens surface other than on the optical axis, and the tangent plane of the lens surface at the pole point intersects the optical axis perpendicularly, and the lens group closest to the object of the intermediate group is a first intermediate lens group having positive refractive power, wherein Bfw is the back focus at the air-equivalent distance of the entire system when focused on an object at infinity at the wide-angle end, fw is the focal length of the entire system when focused on an object at infinity at the wide-angle end, and ωw is the maximum half angle of view when focused on an object at infinity at the wide-angle end, A variable magnification optical system that satisfies the conditional expression (1) expressed as follows: 0.25<Bfw / (fw×tan ωw)<2 (1).

2. A variable magnification optical system according to claim 1, which satisfies the conditional expression (2) expressed as follows: 2<TLw / (fw×tan ωw)<16 (2), where TLw is the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw.

3. A variable magnification optical system according to claim 1, which satisfies conditional expression (3) expressed as follows: 2.5<fPmax / fMmax<30 (3), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, and fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group.

4. A variable magnification optical system according to claim 1, which satisfies conditional expression (4) expressed as follows: 3.8<fPmax / (-fNmax)<40 (4), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, and fNmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the negative front group.

5. A variable magnification optical system according to claim 1, which satisfies the conditional expression (5) expressed as follows: 0.15<FNot / (ft / fw)<1.6 (5), where FNot is the maximum F-number when focused on an object at infinity at the telephoto end, and ft is the focal length of the entire system when focused on an object at infinity at the telephoto end.

6. The variable magnification optical system according to claim 1, wherein the final lens group includes at least one lens surface having the polar point.

7. The variable magnification optical system according to claim 6, wherein the final lens group includes two or more lenses each including at least one lens surface having the polar point.

8. The variable magnification optical system according to claim 7, wherein the final lens group includes three or more lenses, each of which includes at least one lens surface having a polar point.

9. A variable magnification optical system according to claim 6, wherein a focusing group that moves along the optical axis during focusing is disposed closest to the image side of said intermediate group.

10. A variable magnification optical system according to claim 6, which satisfies conditional expression (6) expressed as follows: 0≦DEair / DGE<0.45 (6), where DEair is the sum of the air spaces on the optical axis within the final lens group, and DGE is the distance on the optical axis from the lens surface of the final lens group closest to the object to the lens surface of the final lens group closest to the image.

11. A variable magnification optical system according to claim 10, which satisfies conditional expression (7) expressed as follows: 0.05<DGE / TLw<0.3 (7), where TLw is the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw.

12. The variable magnification optical system according to claim 11, which satisfies the conditional expression (7-1) expressed as follows: 0.08<DGE / TLw<0.25 (7-1).

13. A variable magnification optical system according to claim 6, wherein the final lens group includes a lens having at least one lens surface that faces a convex shape toward the object side in the paraxial region and has the polar point.

14. A variable magnification optical system according to claim 1, wherein the negative front group includes a first aspherical lens element having a concave shape facing the object side in the paraxial region and an inflection point on the object side lens surface where the concave and convex shapes change midway from on the optical axis toward the periphery.

15. A variable magnification optical system according to claim 1, wherein the negative front group includes a second aspherical lens having a concave shape facing the image side in the paraxial region and an inflection point on the image side lens surface where the concave and convex shapes change midway from on the optical axis toward the periphery.

16. A variable magnification optical system according to claim 1, wherein the intermediate group includes a third aspherical lens having a biconvex shape in the paraxial region and an inflection point on its lens surface where the concave-convex shape changes midway from on the optical axis to the periphery.

17. The variable magnification optical system according to claim 1, wherein the intermediate group includes a plurality of negative lenses.

18. The variable magnification optical system according to claim 1, wherein the positive front group includes a negative lens and a positive lens.

19. A variable magnification optical system according to claim 14, which satisfies conditional expression (8) expressed as follows: -10<Ra1y / Ra1c<-0.05 (8), where Ra1y is the radius of curvature of the object-side surface of said first aspherical lens at the position of the maximum effective diameter, and Ra1c is the paraxial radius of curvature of the object-side surface of said first aspherical lens.

20. A variable magnification optical system according to claim 19, wherein the lens located closest to the object side in the negative front group is the first aspherical lens.

21. A variable magnification optical system according to claim 15, which satisfies conditional expression (9) expressed as follows: -1.5<Ra2y / Ra2c<0 (9), where Ra2y is the radius of curvature of the image-side surface of the second aspherical lens at the position of the maximum effective diameter, and Ra2c is the paraxial radius of curvature of the image-side surface of the second aspherical lens.

22. A variable magnification optical system according to claim 21, wherein the lens in said negative front group arranged closest to the image side is said second aspherical lens.

23. A variable magnification optical system according to claim 16, wherein the object-side third aspherical lens arranged closest to the object side among the third aspherical lenses included in the intermediate group has at least one of the pole points on its image-side lens surface, and satisfies conditional expression (10) expressed as follows: 0.45<PDmin / EDa3<0.95 (10) where PDmin is the smallest diameter of circles centered on a point on the optical axis and passing through each of the pole points on the image-side lens surface of the object-side third aspherical lens, and EDa3 is the effective diameter of the image-side surface of the object-side third aspherical lens.

24. A variable magnification optical system according to claim 23, wherein the lens element arranged closest to the object side in said intermediate group is said object-side third aspherical lens element.

25. A variable magnification optical system according to claim 1, which satisfies conditional expression (11) expressed as follows: 1.5<fPmax / (ft / FNot)<11 (11), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group, ft is the focal length of the entire system when focused on an object at infinity at the telephoto end, and FNot is the maximum open F-number when focused on an object at infinity at the telephoto end.

26. A variable magnification optical system according to claim 1, which satisfies conditional expression (12) expressed as follows: 2<TLw / fw<15 (12) where TLw is the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw.

27. A variable magnification optical system according to claim 1, which satisfies the following conditional expression (13): 0.1<tan ωw / FNow<0.6 (13), where FNow is the maximum open F-number when focused on an object at infinity at the wide-angle end.

28. A variable magnification optical system according to claim 1, which satisfies the following conditional expression (14): 0.05<fw / fPmax<1 (14), where fPmax is the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group.

29. If the focal length of the lens group having the strongest refractive power among the lens groups included in the positive front group is fPmax, and the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, then 1<fPmax / (fw×ft). １／２ 2. The variable magnification optical system according to claim 1, which satisfies the conditional expression (15) expressed as follows: <15 (15).

30. A variable magnification optical system as claimed in claim 1, which satisfies conditional expression (16) expressed as follows: 0.7<TLw / ft<4 (16) where TLw is the sum of the distance on the optical axis from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw, and ft is the focal length of the entire system when focused on an object at infinity at the telephoto end.

31. A variable magnification optical system according to claim 1, which satisfies the following conditional expression (17): 2<ft / fw<10 (17) where ft is the focal length of the entire system when focused on an object at infinity at the telephoto end.

32. If the focal length of the lens group having the strongest refractive power among the lens groups included in the negative front group is fNmax, and the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, then 0.15<(-fNmax) / (fw×ft). １／２ 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (18) expressed as follows: <1 (18).

33. A variable magnification optical system as claimed in claim 1, which satisfies conditional expression (19) expressed as follows: 0.95<TLt / TLw<2 (19) where TLt is the sum of the axial distance from the lens surface of said positive front group nearest to the object to the lens surface of said final lens group nearest to the image when focused on an object at infinity at the telephoto end, and the back focus in the air-equivalent distance of the entire system, and TLw is the sum of the axial distance from the lens surface of said positive front group nearest to the object to the lens surface of said final lens group nearest to the image when focused on an object at infinity at the wide-angle end, and Bfw.

34. A variable magnification optical system according to claim 1, which satisfies the following conditional expression (20): −0.3<fw / fE<0.6 (20) where fE is the focal length of the final lens group.

35. A variable magnification optical system according to claim 1, which satisfies the conditional expression (21) expressed as follows: -0.4<ft / fE<1.5 (21), where ft is the focal length of the entire system when focused on an object at infinity at the telephoto end, and fE is the focal length of the final lens group.

36. If the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group is fMmax, and the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, then 0.05<fMmax / (fw×ft). １／２ 2. The variable magnification optical system according to claim 1, which satisfies the conditional expression (22) expressed as follows: <2 (22).

37. A variable magnification optical system according to claim 1, which satisfies the conditional expression (23) expressed as follows: 0.2<fw / fMmax<1.5 (23), where fMmax is the focal length of the lens group having the strongest positive refractive power among the lens groups included in the intermediate group.

38. A variable magnification optical system according to claim 1, wherein the positive front group includes a cemented lens in which a negative meniscus lens having a convex shape facing the object side and a positive lens having a convex shape facing the object side are cemented together in this order from the object side to the image side, and satisfies conditional expression (24) expressed by the following formula: 1.94<Nn+0.01×νn<2.5 (24) where Nn is the refractive index for the d-line of the negative meniscus lens of the cemented lens, and νn is the Abbe number of the negative meniscus lens of the cemented lens based on the d-line.

39. A variable magnification optical system according to claim 38, which satisfies conditional expression (25) expressed by the following formula: 2<Np+0.01×νp<2.6 (25) where Np is the refractive index of the positive lens in the cemented lens with respect to the d-line, and νp is the Abbe number of the positive lens in the cemented lens with respect to the d-line.

40. A variable magnification optical system according to claim 1, which satisfies the following conditional expression (26): 35<νPpave<96 (26) where νPpave is the average Abbe number based on the d-line of all positive lenses included in the positive front group.

41. A variable magnification optical system according to claim 1, which satisfies conditional expression (27) expressed by: 0.1<DEIw / TLw<0.5 (27) where DEIw is the sum of the axial distance from the lens surface of the final lens group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw, and TLw is the sum of the axial distance from the lens surface of the positive front group closest to the object to the lens surface of the final lens group closest to the image when focused on an object at infinity at the wide-angle end and Bfw.

42. A variable magnification optical system according to claim 1, wherein the final lens group includes two or more lenses, and at least two lenses satisfy conditional expression (28) expressed by 1.85<NE+0.01×νE<2.14 (28), where NE is the refractive index of the lenses included in the final lens group with respect to the d-line and νE is the Abbe number of the lenses included in the final lens group with respect to the d-line.

43. A variable magnification optical system according to claim 1, wherein the intermediate group includes one or two focusing groups that move along the optical axis during focusing.

44. A variable magnification optical system according to claim 1, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group and a second intermediate lens group having negative refractive power.

45. A variable magnification optical system according to claim 44, which satisfies conditional expression (29) expressed as follows: 0.05<fM1 / (-fM2)<1.5 (29) where fM1 is the focal length of the first intermediate lens group and fM2 is the focal length of the second intermediate lens group.

46. ​​A variable magnification optical system according to claim 45, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group, the second intermediate lens group, and a third intermediate lens group having positive refractive power.

47. A variable magnification optical system according to claim 46, which satisfies conditional expression (30) expressed as follows: 0.1<(-fM2 / fM3)<4 (30) where the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3.

48. A variable magnification optical system according to claim 1, wherein the intermediate group comprises, in order from the object side to the image side, the first intermediate lens group and a second intermediate lens group having positive refractive power.

49. A variable magnification optical system according to claim 48, which satisfies conditional expression (31) expressed as follows: 0.05<fM1 / fM2<2 (31) where fM1 is the focal length of the first intermediate lens group and fM2 is the focal length of the second intermediate lens group.

50. A variable magnification optical system according to claim 1, wherein the intermediate group includes, in order from the object side to the image side, at least the first intermediate lens group, a second intermediate lens group having positive refractive power, and a third intermediate lens group having negative refractive power.

51. A variable magnification optical system according to claim 50, which satisfies conditional expression (30A) expressed as follows: 0.1<(-fM2 / fM3)<4 (30A), where the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3.

52. A variable magnification optical system according to claim 1, wherein the intermediate group includes, in succession from the object side to the image side, at least the first intermediate lens group, a second intermediate lens group having positive refractive power, and a third intermediate lens group having positive refractive power.

53. A variable magnification optical system according to claim 52, which satisfies conditional expression (31A) expressed as follows: 0.02<fM1 / fM2<0.7 (31A), where fM1 is the focal length of the first intermediate lens group and fM2 is the focal length of the second intermediate lens group.

54. A variable magnification optical system according to claim 52, which satisfies conditional expression (32) expressed as follows: 0.3<fM2 / fM3<4.5 (32) where the focal length of the second intermediate lens group is fM2 and the focal length of the third intermediate lens group is fM3.

55. A variable magnification optical system according to claim 53, wherein the intermediate group consists of, in order from the object side to the image side, the first intermediate lens group, the second intermediate lens group, the third intermediate lens group, and a fourth intermediate lens group having positive refractive power.

56. A variable magnification optical system according to claim 55, which satisfies conditional expression (33) expressed as follows: 0.3<fM3 / fM4<2.5 (33) where the focal length of the third intermediate lens group is fM3 and the focal length of the fourth intermediate lens group is fM4.

57. An imaging device comprising a variable magnification optical system according to any one of claims 1 to 56.

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