Variable magnification optical system and imaging device

Abstract

This variable magnification optical system comprises, in order from the object side: a first lens group having positive refractive power; a second lens group having negative refractive power; an intermediate group; and a final lens group having refractive power. The intermediate group comprises one to five lens groups inclusive. An aperture stop is disposed between a lens surface closest to the image side in the second lens group and a lens surface closest to the object side in the final lens group. The first lens group includes a negative lens and a positive lens continuously in order from the side closest to the object to the image side. 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] Conventionally, zoom lenses described in Japanese Patent Application Laid-Open Nos. 2016-109720, 2016-109721, and 2021-009217 are known as variable magnification optical systems that can be used in imaging devices such as digital cameras.

[0003] There is a demand for a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and has high optical performance over the entire range of magnification. These demands are becoming higher every year.

[0004] The present disclosure provides a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and has high optical performance over the entire range of magnification, and an imaging device that includes this variable magnification optical system.

[0005] A variable magnification optical system according to one aspect of the present disclosure comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate group, and a final lens group having refractive power, the intermediate group consisting of one or more and five or less lens groups, and during magnification variation, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the intermediate group changes, and the distance between the intermediate group and the final lens group changes, and when the intermediate group consists of multiple lens groups, the distances between all of the adjacent lens groups in the intermediate group change during magnification variation, an aperture stop is disposed between the lens surface of the second lens group closest to the image side and the lens surface of the final lens group closest to the object side, and the first lens group comprises, in order from the most object side to the image side, a first lens which is a negative lens, a second lens which is a positive lens, and a third lens which is a positive lens. and a second lens element, wherein the distance on the optical axis from the object-side surface of the first lens element to the aperture stop when focused on an object at infinity at the wide-angle end is DDL1STw, the sum of the distance on the optical axis from the object-side surface of the first lens element 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 the back focus of the entire system in air-equivalent distance is TLw, the maximum F-number when focused on an object at infinity at the telephoto end is Fnot, the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, the focal length of the entire system when focused on an object at infinity at the wide-angle end is fw, the back focus of the entire system at the wide-angle end in air-equivalent distance is Bfw, and the maximum half angle of view when focused on an object at infinity at the telephoto end is ωt. The following conditional expressions (1), (2), and (3) are satisfied: 0<DDL1STw / TLw<0.5 (1) 0.5<Fnot / (ft / fw)<1.3 (2) 0.15<Bfw / (ft×tan ωt)<2 (3)

[0006] It is preferable that the variable magnification optical system of the above aspect satisfies the conditional expression (4) expressed as follows: 1<fw / (ft×tan ωt)<1.4 (4).

[0007] When the focal length of the first lens group is f1 and the composite focal length of the optical system from the first lens to the aperture stop when focused on an object at infinity at the wide-angle end is fL1STw, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (5) expressed as: −6.6<f1 / fL1STw<−1.5 (5).

[0008] When the focal length of the first lens group is f1 and the focal length of the first lens is fL1, it is preferable that the variable magnification optical system of the above aspect satisfies the conditional expression (6) expressed as: −0.9<f1 / fL1<−0.05 (6).

[0009] When the composite focal length of the optical system from the first lens to the aperture stop when focused on an object at infinity at the wide-angle end is fL1STw, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (7) expressed as: −1.4<fw / fL1STw<−0.3 (7).

[0010] When the combined focal length of the optical system from the first lens to the aperture stop when focused on an object at infinity at the wide-angle end is fL1STw, the focal length of the first lens group is f1, and the focal length of the first lens is fL1, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expressions (4), (5), (6), and (7) expressed as follows: 1<fw / (ft×tanωt)<1.4 (4) −6.6<f1 / fL1STw<−1.5 (5) −0.9<f1 / fL1<−0.05 (6) −1.4<fw / fL1STw<−0.3 (7)

[0011] It is preferable that the variable magnification optical system of the above embodiment satisfies the conditional expression (8) expressed as follows: 2<TLw / (ft×tan ωt)<9 (8).

[0012] When the lateral magnification of the second lens group when focused on an object at infinity at the telephoto end is β2t and the lateral magnification of the second lens group when focused on an object at infinity at the wide-angle end is β2w, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (9) expressed as 1.1<β2t / β2w<3 (9).

[0013] When the distance on the optical axis between the first lens group and the second lens group when focused on an object at infinity at the wide-angle end is DDG12w, the distance on the optical axis between the first lens group and the second lens group when focused on an object at infinity at the telephoto end is DDG12t, and the sum of the distance on the optical axis from the object-side surface of the first lens 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 of the entire system in air-equivalent distance when focused on an object at infinity at the telephoto end is TLt, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (10) expressed as 0.1<|DDG12w-DDG12t| / TLt<0.3 (10).

[0014] When the focal length of the first lens group is taken as f1, it is preferable that the variable magnification optical system of the above aspect satisfies the conditional expression (11) expressed as follows: 0.2<DDL1STw / f1<0.8 (11).

[0015] When the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (12) expressed as follows: 3<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <9 (12).

[0016] It is preferable that the variable magnification optical system of the above aspect satisfies the conditional expression (13) expressed as follows: 3<TLw / fw<8 (13).

[0017] When the sum of the distance on the optical axis from the object-side surface of the first lens to the lens surface of the final lens group closest to the image side when focused on an object at infinity at the telephoto end and the back focus of the entire system in air equivalent distance is defined as TLt, the variable magnification optical system of the above aspect preferably satisfies conditional expression (14) expressed as 1.5<TLt / ft<3 (14).

[0018] When the sum of the distance on the optical axis from the object-side surface of the first lens to the lens surface of the final lens group closest to the image side when focused on an object at infinity at the telephoto end and the back focus of the entire system in air equivalent distance is TLt, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (15) expressed as 5<TLt / (ft×tanωt)<11 (15).

[0019] When the focal length of the first lens group is taken as f1, it is preferable that the variable magnification optical system of the above aspect satisfies the conditional expression (16) expressed as follows: 3<f1 / fw<7 (16).

[0020] When the focal length of the first lens group is f1 and the focal length of the second lens group is f2, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (17) expressed as follows: 3<f1 / (-f2)<9 (17)

[0021] When the focal length of the first lens group is taken as f1, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (18) expressed as follows: 2<f1 / (ft / Fnot)<7 (18).

[0022] When the focal length of the first lens group is f1, the variable magnification optical system of the above aspect satisfies the following condition: 1.8<f1 / (fw×ft) １／２ It is preferable to satisfy the conditional expression (19) expressed as follows:<4.2 (19)

[0023] When the distance on the optical axis from the object-side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end is Denw and the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (20) expressed as follows: 2<Denw / {(fw×tanωw)×log(ft / fw)}<4.5 (20)

[0024] When the distance on the optical axis from the object-side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end is Denw, the variable magnification optical system of the above aspect satisfies the following condition: 0.5<Denw / (fw×ft) １／２ It is preferable to satisfy the following conditional expression (21): <1 (21).

[0025] When the central thickness of the first lens is d1, the distance on the optical axis from the object-side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end is Denw, and the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (22) expressed as follows: 0.04<d1 / (Denw×tanωw)<0.09 (22)

[0026] The distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity at the wide-angle end is Dexw, and the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with the image plane as the reference. When an optical element having no refractive power is disposed between the image plane and the paraxial exit pupil position, and Dexw is calculated using the air-equivalent distance for the optical element, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (23) expressed as: −0.65<fw / Dexw<−0.2 (23).

[0027] When the effective diameter of the object-side surface of the first lens is EDf and the effective diameter of the lens surface of the final lens group closest to the image side is EDr, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (24) expressed as 1.5<EDf / EDr<3 (24).

[0028] When the effective diameter of the object-side surface of the first lens is EDf, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (25) expressed as follows: 0.35<EDf / TLw<0.65 (25).

[0029] It is preferable that the variable magnification optical system of the above aspect satisfies the conditional expression (26) expressed as follows: 2.2<ft / fw<4.8 (26).

[0030] When the refractive index of the first lens with respect to the d-line is NdL1 and the Abbe number of the first lens based on the d-line is vdL1, it is preferable that the variable magnification optical system of the above aspect satisfies the conditional expressions (27), (28), and (29) expressed as follows: 1.8<NdL1<2.01 (27) 15<vdL1<45 (28) 2<NdL1+0.01×vdL1<2.5 (29)

[0031] When the refractive index of the second lens for the d-line is NdL2 and the Abbe number of the second lens based on the d-line is vdL2, it is preferable that the variable magnification optical system of the above aspect satisfies the conditional expressions (30), (31), and (32) expressed as follows: 1.43<NdL2<1.81 (30) 45<vdL2<96 (31) 2<NdL2+0.01×vdL2<2.5 (32).

[0032] It is preferable that the variable magnification optical system of the above aspect includes at least one focusing group that moves during variable magnification and focusing, and satisfies conditional expression (33) expressed as follows: 0.3<|ffoc / fMt|<4 (33) where ffoc is the focal length of the focusing group with the smallest absolute value of focal length among the focusing groups included in the variable magnification optical system, and fMt is the focal length of the intermediate group when focused on an object at infinity at the telephoto end.

[0033] The variable magnification optical system of the above aspect includes at least one focusing group that moves during magnification variation and focusing, and among the focusing groups included in the variable magnification optical system, the focusing group with the largest absolute value of focal length is at the telephoto end where the lateral magnification is focused on an object at infinity, and the combined lateral magnification of all lenses located on the image side of the focusing group with the largest absolute value of focal length is at the telephoto end where the combined lateral magnification is focused on an object at infinity, is βfRt. ２ ) × βfRt ２ It is preferable to satisfy the conditional expression (34) expressed as: |<8 (34).

[0034] One of the lens groups included in the intermediate group may be configured to be a focusing group that moves during zooming and focusing.

[0035] The focusing group may be configured to consist of one positive lens and two negative lenses. In this configuration, if the negative lens closest to the image side of the focusing group is an aspherical lens, it is preferable that the variable magnification optical system of the above aspect satisfy conditional expression (35) expressed as follows: 0.1<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<3 (35), where Rcnf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcnr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Rynf is the radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter, and Rynr is the radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter.

[0036] The focusing group may be configured to include one negative lens and two positive lenses. In this configuration, if the positive lens closest to the image side of the focusing group is an aspherical lens, it is preferable that the variable magnification optical system of the above aspect satisfy conditional expression (36) expressed as follows: −120<(1 / Rcpf−1 / Rcpr) / (1 / Rypf−1 / Rypr)<−3 (36), where Rcpf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcpr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Rypf is the radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter, and Rypr is the radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter.

[0037] The focusing group may be configured to include one positive lens and one negative lens.

[0038] The focusing group may be configured to consist of one negative lens. In this configuration, if the negative lens of the focusing group is an aspherical lens, it is preferable that the variable magnification optical system of the above aspect satisfy conditional expression (37) expressed as follows: 0.1<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<3.5 (37) where Rcsnf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcsnr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Rysnf is the radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter, and Rysnr is the radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter.

[0039] Two of the lens groups included in the intermediate group may be configured as focusing groups that move while changing the distance between them during magnification and focusing.

[0040] Of the two lens groups that are focusing groups, if the lens group located on the object side is designated as the object-side focusing group and the lens group located on the image side is designated as the image-side focusing group, the object-side focusing group may be configured to consist of one negative lens and one positive lens, and the image-side focusing group may be configured to consist of one positive lens.

[0041] When the positive lens of the image-side focusing group is an aspherical lens, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (38) expressed as follows: 1<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<100 (38) where Rcipf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcipr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Ryipf is the radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter, and Ryipr is the radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter.

[0042] Of the two lens groups that are focusing groups, if the lens group located on the object side is designated as the object-side focusing group and the lens group located on the image side is designated as the image-side focusing group, the object-side focusing group may be configured to consist of one positive lens and one negative lens, and the image-side focusing group may be configured to consist of one negative lens.

[0043] When the negative lens of the image-side focusing group is an aspherical lens, it is preferable that the variable magnification optical system of the above aspect satisfies conditional expression (39) expressed as follows: 0.1<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<3.5 (39) where Rcinf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcinr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Ryinf is the radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter, and Ryinr is the radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter.

[0044] The variable magnification optical system of the above aspect may be configured to include a plurality of lens groups that move along the same movement locus when varying magnification from the wide-angle end to the telephoto end.

[0045] The intermediate group preferably includes an aperture stop closest to the object side.

[0046] The intermediate group may be configured to be composed of, in order from the object side to the image side, a lens group having positive refractive power and a lens group having negative refractive power, and the final lens group has positive refractive power.

[0047] The final lens group may be configured to be fixed relative to the image plane during zooming.

[0048] When the final lens group is made up of one positive aspherical lens, it is preferable that, when the paraxial radius of curvature of the object-side surface of the aspherical lens is RcEpf, the paraxial radius of curvature of the image-side surface of the aspherical lens is RcEpr, the radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter of the aspherical lens is RyEpf, and the radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter of the aspherical lens is RyEpr, the variable magnification optical system of the above aspect satisfies conditional expression (40) expressed as follows: 0.1<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<5 (40)

[0049] The final lens group may be configured to move during magnification variation.

[0050] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0051] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0052] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0053] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0054] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0055] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group may be configured to have positive refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0056] The intermediate group may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group may be configured to have negative refractive power. In this configuration, the final lens group may be configured to move during zooming.

[0057] An imaging device according to another aspect of the present disclosure includes the variable magnification optical system according to the above aspect of the present disclosure.

[0058] 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.

[0059] In this specification, "a lens group having positive refractive power" and "a lens group having positive refractive power" mean that the lens group as a whole has positive refractive power. Similarly, "a lens group having negative refractive power" and "a lens group having negative refractive power" mean that the lens group as a whole has negative refractive power. In this specification, the terms "first lens group," "second lens group," "lens group," "final lens group," and "focusing group" are not limited to configurations consisting of multiple lenses, and may also be configurations consisting of only one lens.

[0060] A hybrid aspherical lens (a lens in which a spherical lens and an aspherical film formed on the spherical 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 sign of the 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.

[0061] In this specification, "total system" means 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. Unless otherwise specified, the values ​​used in the conditional expressions are values ​​based on the d-line when focused on an object at infinity.

[0062] The terms "d-line," "C-line," "F-line," and "g-line" used in this specification are emission lines. The wavelength of the d-line is treated as 587.56 nm (nanometers), the wavelength of the C-line is treated as 656.27 nm (nanometers), the wavelength of the F-line is treated as 486.13 nm (nanometers), and the wavelength of the g-line is treated as 435.84 nm (nanometers).

[0063] According to the present disclosure, it is possible to provide a variable magnification optical system that is compact, has a small F-number over the entire range of magnification, and has high optical performance over the entire range of magnification, and an imaging device that includes this variable magnification optical system.

[0064] 1A and 1B are diagrams illustrating 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. 1C is a diagram for explaining symbols in conditional expressions; FIG. 1D is a diagram for explaining the positions of an effective diameter and a maximum effective diameter; FIG. 1E is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 2; FIG. 1F is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 3; FIG. 1G is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 3; FIG. 1H is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 4; FIG. 1H is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 5; FIG. 1I is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 5; FIG. 1I is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 6; FIG. 1I is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 6; FIG. 1J is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 7; FIG. 1J is a diagram illustrating a cross-sectional view and a movement locus of the configuration of a variable magnification optical system of Example 7; FIG. 10 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. 11 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. 12 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. 13 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. 14 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 14. FIG. 15 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. 16 is a diagram showing a cross-sectional view of the configuration of a variable magnification optical system of Example 16. FIG. 16 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. 17 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. 18 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. 19 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. 14 is a diagram showing each aberration of the variable magnification optical system of Example 19. Fig. 15 is a diagram showing a cross-sectional view of the configuration of the variable magnification optical system of Example 20 and a movement locus. Fig. 16 is a diagram showing each aberration of the variable magnification optical system of Example 20. 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.

[0065] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0066] FIG. 1 shows a cross-sectional view and a movement trajectory of a variable magnification optical system according to an embodiment of the present disclosure. 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. The example shown in FIG. 1 corresponds to the variable magnification optical system of Example 1, which will be described later. FIG. 1 shows a state in which the lens is focused on an object at infinity, with the left side being the object side and the right side being the image side. FIG. 1 also shows an axial light beam wa and a light beam wb at the wide-angle end and a maximum half angle of view ωw, as well as an axial light beam ta and a light beam tb at the telephoto end and a maximum half angle of view ωt.

[0067] 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 first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an intermediate group GM, and a final lens group GE having refractive power. The intermediate group GM comprises at least one lens group and at most five lens groups. By making the first lens group G1 a lens group having positive refractive power, it is possible to shorten the overall length, which is advantageous for achieving both compactness and a high zoom ratio. Furthermore, by making the first lens group G1 a lens group having positive refractive power, the height of light rays incident on the second lens group G2 is lowered, which is advantageous for suppressing aberration fluctuations during magnification.

[0068] The aperture stop St is disposed between the lens surface of the second lens group G2 closest to the image and the lens surface of the final lens group GE closest to the object. This configuration allows the aperture unit to be made compact, which is advantageous for making the entire optical system compact.

[0069] When the magnification is changed, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the middle group GM changes, and the distance between the middle group GM and the final lens group GE changes. If the middle group GM is made up of multiple lens groups, the distances between all of the adjacent lens groups in the middle group GM change when the magnification is changed. Changing the distances between multiple groups when the magnification is changed is advantageous for suppressing various aberrations throughout the entire range of magnification.

[0070] In this specification, the "first lens group G1," "second lens group G2," the "lens group" included in the intermediate group GM, and the "final lens group GE" are components of a variable magnification optical system, and are portions including at least one lens separated by an air gap that changes during magnification. During magnification, each lens group is moved or fixed, and the mutual spacing between lenses within each lens group does not change. In other words, in this specification, a group in which the spacing between adjacent groups changes during magnification, but the total spacing between adjacent lenses within itself does not change, is defined as one lens group. Note that the "lens group" may also include components other than lenses that do not have refractive power, such as an aperture stop St.

[0071] 1 is composed of, in order from the object side to the image side, a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, and a fifth lens group G5. In the example of Fig. 1, the middle lens group GM is composed of the third lens group G3 and the fourth lens group G4, and the final lens group GE is composed of the fifth lens group G5.

[0072] As an example, each lens group in FIG. 1 is configured as follows. The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 to L42, in order from the object side to the image side. The fifth lens group G5 consists of a single lens, L51. Note that the aperture stop St in FIG. 1 does not indicate the shape or size, but rather its position in the optical axis direction.

[0073] In the example of Fig. 1, during magnification change, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. In Fig. 1, for the moving lens groups, the approximate movement locus of each lens group during magnification change from the wide-angle end to the telephoto end is indicated by arrows between the upper and lower rows.

[0074] In the variable magnification optical system of the present disclosure, the first lens group G1 includes, in succession from the object side to the image side, a first lens which is a negative lens and a second lens which is a positive lens. This configuration facilitates aberration correction within the first lens group G1, which is advantageous for suppressing aberration fluctuations during magnification change. Furthermore, by locating the negative lens closest to the object side, aberration correction is facilitated when the focal length at the wide-angle end is shortened. In the example of FIG. 1 , lens L11 corresponds to the first lens, and lens L12 corresponds to the second lens.

[0075] For example, the first lens group G1 can be configured to consist of, in order from the object side to the image side, a negative lens, a positive lens, and a positive lens, and the second lens group G2 can be configured to consist of, in order from the object side to the image side, a negative lens, a negative lens, a positive lens, and a negative lens.

[0076] The middle group GM can be configured to consist of, in order from the object side to the image side, a lens group having positive refractive power and a lens group having negative refractive power, and the final lens group GE can be configured to have positive refractive power, which is advantageous for achieving both a simple lens drive mechanism and high performance.

[0077] It is preferable that the intermediate group GM includes an aperture stop St closest to the object. In this case, the aperture stop St can be located closer to the first lens group G1, thereby shortening the distance from the lens surface closest to the object in the first lens group G1 to the entrance pupil. This is advantageous for reducing the diameter of the first lens group G1.

[0078] The final lens group GE may be configured to be fixed relative to the image plane Sim during zooming, which simplifies the lens drive mechanism.

[0079] The final lens group GE may be configured to consist of a single positive aspherical lens, which is advantageous for achieving both a simplified lens drive mechanism and high performance.

[0080] The variable magnification optical system of the present disclosure may be configured to include at least one focusing group that moves during magnification change and focusing. Focusing is achieved by moving the focusing group. In the example of FIG. 1 , the focusing group is the fourth lens group G4. The parentheses and right-pointing arrow below the fourth lens group G4 in FIG. 1 indicate that the fourth lens group G4 is a focusing group that moves toward the image side when focusing from an object at infinity to a closest object. Note that although the fourth lens group G4 functions as a focusing group throughout the entire magnification change range, in FIG. 1 , to avoid cluttering the diagram, the parentheses and arrow indicating the focusing group are only included in the lower diagram.

[0081] One of the lens groups included in the intermediate group GM may be configured as a focusing group that moves during zooming and focusing. By placing the focusing group in the intermediate group GM, it is possible to reduce the size of the focusing group, which is advantageous for reducing the size of the entire optical system.

[0082] As an example, the focusing group may be configured to consist of one positive lens and one negative lens, as shown in Figure 1. In this case, the number of lenses in the focusing group can be reduced, which is advantageous in simplifying the mechanism for controlling the focusing group and also makes it easier to achieve fast focusing.

[0083] Alternatively, the focusing group may be configured to consist of a single negative lens. In this case, the number of lenses in the focusing group can be further reduced, which is advantageous in simplifying the mechanism for controlling the focusing group and facilitating faster focusing. In this case, the negative lens in the focusing group may be configured to be an aspherical lens. In this case, aberration fluctuations during focusing can be suppressed, which is advantageous in terms of improving performance.

[0084] The focusing group may be configured to consist of one positive lens and two negative lenses. This is advantageous for improving performance because it can suppress aberration fluctuations during focusing. In this case, the negative lens closest to the image side of the focusing group may be configured to be an aspherical lens. This is advantageous for improving performance because it can suppress aberration fluctuations during focusing.

[0085] The focusing group may be configured to consist of one negative lens and two positive lenses. This is advantageous for improving performance because it can suppress fluctuations in aberrations during focusing. In this case, the positive lens closest to the image side of the focusing group may be configured to be an aspherical lens. This is advantageous for improving performance because it can suppress fluctuations in aberrations during focusing.

[0086] Two of the lens groups included in the intermediate group GM may be configured as focusing groups that move with a varying distance between them during zooming and focusing. By locating the focusing group in the intermediate group GM, the focusing group can be made smaller, which is advantageous for miniaturizing the entire optical system. Furthermore, by employing a floating focus system for focusing with two lens groups, aberration fluctuations during focusing can be effectively suppressed.

[0087] In a configuration in which two of the lens groups included in the intermediate group GM are focusing groups that move while changing the distance between them during magnification and focusing, the lens group located on the object side of the two focusing groups will be called the object-side focusing group, and the lens group located on the image side will be called the image-side focusing group.

[0088] The object-side focusing group may be configured to consist of one negative lens and one positive lens, and the image-side focusing group may be configured to consist of one positive lens. In this case, fluctuations in aberrations during focusing can be suppressed, which is advantageous for improving performance. In this case, the positive lens in the image-side focusing group may be configured to be an aspherical lens. In this case, fluctuations in aberrations during focusing can be suppressed, which is advantageous for improving performance.

[0089] The object-side focusing group may be configured to consist of one positive lens and one negative lens, and the image-side focusing group may be configured to consist of one negative lens. In this case, aberration fluctuations during focusing can be suppressed, which is advantageous for improving performance. In this case, the negative lens in the image-side focusing group may be configured to be an aspherical lens. In this case, aberration fluctuations during focusing can be suppressed, which is advantageous for improving performance.

[0090] Next, a description will be given of a preferred configuration for the conditional expressions of the variable magnification optical system of the present disclosure. Note that in the following description of the conditional expressions, to avoid redundant explanation, the same symbols are used for elements with the same definitions, and some redundant explanations of the 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."

[0091] It is preferable that the variable magnification optical system satisfy the following conditional expression (1). Here, DDL1STw is the distance on the optical axis from the object-side surface of the first lens to the aperture stop St when focused on an object at infinity at the wide-angle end. TLw is the sum of the distance on the optical axis from the object-side surface of the first lens 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 the back focus of the entire system in air-equivalent distance. Note that the "back focus of the entire system in air-equivalent distance" refers to the air-equivalent distance on the optical axis from the lens surface closest to the image plane Sim to the image plane Sim. TLw is the total length when focused on an object at infinity at the wide-angle end. By ensuring that the corresponding value of conditional expression (1) is not below the lower limit, the distance between the aperture stop St and the first lens group G1 does not become too short, and therefore the distance from the object-side surface of the first lens to the entrance pupil position does not become too short, which makes it easier to suppress aberration fluctuations during magnification change. By ensuring that the corresponding value of conditional expression (1) is not equal to or greater than the upper limit, the distance between the aperture stop St and the first lens group G1 is not too great, and therefore the distance from the object-side surface of the first lens to the entrance pupil position does not become too long. This makes it possible to prevent the diameter of the first lens group G1 from becoming too large, facilitating miniaturization. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (1-1), it is even more preferable that it satisfies the following conditional expression (1-2), it is even more preferable that it satisfies the following conditional expression (1-3), and it is even more preferable that it satisfies the following conditional expression (1-4). 0<DDL1STw / TLw<0.5 (1) 0.05<DDL1STw / TLw<0.46 (1-1) 0.1<DDL1STw / TLw<0.43 (1-2) 0.15<DDL1STw / TLw<0.41 (1-3) 0.2<DDL1STw / TLw<0.39 (1-4)

[0092] 2 shows a cross-sectional view of the variable magnification optical system of FIG. 1, and shows, as an example, the distance DDL1STw and the total length TLw of this variable magnification optical system. In FIG. 2, the upper row labeled "Wide" shows the wide-angle end state, and the lower row labeled "Tele" shows the telephoto end state.

[0093] It is preferable that the variable magnification optical system satisfy the following conditional expression (2). Here, Fnot represents the maximum F-number when focused on an object at infinity at the telephoto end. ft represents the focal length of the entire system when focused on an object at infinity at the telephoto end. fw represents the focal length of the entire system when focused on an object at infinity at the wide-angle end. Ensuring that the corresponding value of conditional expression (2) is not equal to or less than the lower limit is advantageous for reducing the size of the entire optical system, and is also advantageous for suppressing various aberrations, particularly at the telephoto end. Ensuring that the corresponding value of conditional expression (2) is not equal to or greater than the upper limit is advantageous for maintaining a small F-number at the telephoto end, and is therefore advantageous for obtaining sufficient brightness at the telephoto end. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (2-1), even more preferable that it satisfy the following conditional expression (2-2), even more preferable that it satisfy the following conditional expression (2-3), and even more preferable that it satisfy the following conditional expression (2-4). 0.5<Fnot / (ft / fw)<1.3 (2) 0.6<Fnot / (ft / fw)<1.2 (2-1) 0.7<Fnot / (ft / fw)<1.2 (2-2) 0.8<Fnot / (ft / fw)<1.1 (2-3) 0.9<Fnot / (ft / fw)<1.1 (2-4)

[0094] It is preferable that the variable magnification optical system satisfy the following conditional expression (3). Here, the back focus of the entire system at the air-equivalent distance at the wide-angle end is defined as Bfw. The maximum half angle of view when focused on an object at infinity at the telephoto end is defined as ωt. tan is the tangent. As an example, FIG. 2 shows the above back focus Bfw. By ensuring that the corresponding value of conditional expression (3) is not equal to or less than the lower limit, the back focus does not become too short, making it easy to attach a mount exchange mechanism. By ensuring that the corresponding value of conditional expression (3) is not equal to or greater than the upper limit, the back focus does not become too long, making it easy to achieve compactness. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (3-1), even more preferable that it satisfy the following conditional expression (3-2), even more preferable that it satisfy the following conditional expression (3-3), and even more preferable that it satisfy the following conditional expression (3-4). 0.15<Bfw / (ft×tanωt)<2 (3) 0.2<Bfw / (ft×tanωt)<1.7 (3-1) 0.25<Bfw / (ft×tanωt)<1.4 (3-2) 0.3<Bfw / (ft×tanωt)<1.1 (3-3) 0.35<Bfw / (ft×tanωt)<0.8 (3-4)

[0095] It is preferable that the variable magnification optical system satisfies the following conditional expression (4). By ensuring that the corresponding value of conditional expression (4) 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 (4) is not equal to or greater than the upper limit, it is easy to obtain a wide angle of view at the wide-angle end. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (4-1), it is even more preferable that it satisfies the following conditional expression (4-2), it is even more preferable that it satisfies the following conditional expression (4-3), and it is even more preferable that it satisfies the following conditional expression (4-4). 1<fw / (ft×tanωt)<1.4 (4) 1.05<fw / (ft×tanωt)<1.35 (4-1) 1.05<fw / (ft×tanωt)<1.3 (4-2) 1.05<fw / (ft×tanωt)<1.25 (4-3) 1.1<fw / (ft×tanωt)<1.2 (4-4)

[0096] It is preferable that the variable magnification optical system satisfy the following conditional expression (5). Here, the focal length of the first lens group G1 is defined as f1. The composite focal length of the optical system from the first lens to the aperture stop St when focused on an object at infinity at the wide-angle end is defined as fL1STw. By ensuring that the corresponding value of conditional expression (5) is not equal to or less than the lower limit, the refractive power of the first lens group G1 does not become too weak, making it easy to reduce the size of the first lens group G1. By ensuring that the corresponding value of conditional expression (5) is not equal to or greater than the upper limit, the refractive power of the first lens group G1 does not become too strong, making it easy to suppress aberration fluctuations during magnification variation. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (5-1), even more preferable that it satisfy the following conditional expression (5-2), even more preferable that it satisfy the following conditional expression (5-3), and even more preferable that it satisfy the following conditional expression (5-4). -6.6<f1 / fL1STw<-1.5 (5) -6.2<f1 / fL1STw<-1.8 (5-1) -5.8<f1 / fL1STw<-2.1 (5-2) -5.4<f1 / fL1STw<-2.4 (5-3) -5<f1 / fL1STw<-2.7 (5-4)

[0097] When the focal length of the first lens is fL1, it is preferable that the variable magnification optical system satisfy the following conditional expression (6). By ensuring that the corresponding value of conditional expression (6) is not below the lower limit, the refractive power of the negative lens closest to the object does not become too strong, making it easy to suppress high-order aberrations at the telephoto end. Alternatively, the refractive power of the first lens group G1 does not become too weak, making it easy to reduce the size of the first lens group G1. Note that in this specification, "high-order" in relation to aberrations means fifth order or higher. By ensuring that the corresponding value of conditional expression (6) is not above the upper limit, the refractive power of the first lens group G1 does not become too strong, making it easy to suppress aberration fluctuations during magnification. Alternatively, the refractive power of the negative lens closest to the object does not become too weak, making it easy to suppress axial chromatic aberrations at the telephoto end. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (6-1), even more preferable that the following conditional expression (6-2) is satisfied, even more preferable that the following conditional expression (6-3) is satisfied, and even more preferable that the following conditional expression (6-4) is satisfied: -0.9<f1 / fL1<-0.05 (6) -0.8<f1 / fL1<-0.05 (6-1) -0.7<f1 / fL1<-0.1 (6-2) -0.7<f1 / fL1<-0.15 (6-3) -0.6<f1 / fL1<-0.2 (6-4)

[0098] 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 equal to or less than the lower limit, it is advantageous for suppressing various aberrations. By ensuring that the corresponding value of conditional expression (7) is not equal to or greater than the upper limit, it is easy to obtain a wide angle of view at the wide-angle end. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (7-1), it is even more preferable that it satisfies the following conditional expression (7-2), it is even more preferable that it satisfies the following conditional expression (7-3), and it is even more preferable that it satisfies the following conditional expression (7-4). -1.4<fw / fL1STw<-0.3 (7) -1.3<fw / fL1STw<-0.4 (7-1) -1.2<fw / fL1STw<-0.5 (7-2) -1.1<fw / fL1STw<-0.6 (7-3) -1<fw / fL1STw<-0.7 (7-4)

[0099] It is preferable that the variable magnification optical system satisfies the following conditional expression (8). By ensuring that the corresponding value of conditional expression (8) is not equal to or less than the lower limit, it becomes easy to suppress various aberrations throughout the entire range of magnification. By ensuring that the corresponding value of conditional expression (8) is not equal to or greater than the upper limit, it becomes advantageous for reducing the size of the entire optical system. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (8-1), it is even more preferable that it satisfies the following conditional expression (8-2), it is even more preferable that it satisfies the following conditional expression (8-3), and it is even more preferable that it satisfies the following conditional expression (8-4). 2<TLw / (ft×tanωt)<9 (8) 2.5<TLw / (ft×tanωt)<8 (8-1) 3<TLw / (ft×tanωt)<7.5 (8-2) 3.5<TLw / (ft×tanωt)<7 (8-3) 4<TLw / (ft×tanωt)<6.5 (8-4)

[0100] It is preferable that the variable magnification optical system satisfy the following conditional expression (9). Here, the lateral magnification of the second lens group G2 when focused on an object at infinity at the telephoto end is β2t. The lateral magnification of the second lens group G2 when focused on an object at infinity at the wide-angle end is β2w. Ensuring that the corresponding value of conditional expression (9) is not equal to or less than the lower limit is advantageous for achieving a high variable magnification ratio. Ensuring that the corresponding value of conditional expression (9) is not equal to or greater than the upper limit is advantageous for suppressing aberration fluctuations during magnification variation. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (9-1), even more preferable that it satisfy the following conditional expression (9-2), even more preferable that it satisfy the following conditional expression (9-3), and even more preferable that it satisfy the following conditional expression (9-4). 1.1<β2t / β2w<3 (9) 1.2<β2t / β2w<2.7 (9-1) 1.2<β2t / β2w<2.4 (9-2) 1.3<β2t / β2w<2.1 (9-3) 1.3<β2t / β2w<1.9 (9-4)

[0101] It is preferable that the variable magnification optical system satisfy the following conditional expression (10). Here, the axial distance between the first lens group G1 and the second lens group G2 when focused on an object at infinity at the wide-angle end is DDG12w. The axial distance between the first lens group G1 and the second lens group G2 when focused on an object at infinity at the telephoto end is DDG12t. The sum of the axial distance from the object-side surface of the first lens to the lens surface of the final lens group GE closest to the image and the back focus of the entire system in air equivalent distance when focused on an object at infinity at the telephoto end is TLt. TLt is the total length when focused on an object at infinity at the telephoto end. As an example, FIG. 2 shows the above-mentioned distances DDG12w, DDG12t, and total length TLt. Ensuring that the corresponding value of conditional expression (10) is not below the lower limit is advantageous in ensuring an effective variable magnification ratio. By ensuring that the corresponding value of conditional expression (10) is not equal to or greater than the upper limit, it is advantageous for suppressing changes in the position of the center of gravity when changing magnification. Also, it is advantageous for suppressing distortion when changing magnification. In order to obtain better characteristics, it is more preferable for the variable magnification optical system to satisfy the following conditional expression (10-1), even more preferable for it to satisfy the following conditional expression (10-2), even more preferable for it to satisfy the following conditional expression (10-3), and even more preferable for it to satisfy the following conditional expression (10-4). 0.1<|DDG12w-DDG12t| / TLt<0.3 (10) 0.12<|DDG12w-DDG12t| / TLt<0.28 (10-1) 0.13<|DDG12w-DDG12t| / TLt<0.26 (10-2) 0.15<|DDG12w-DDG12t| / TLt<0.23 (10-3) 0.16<|DDG12w-DDG12t| / TLt<0.2 (10-4)

[0102] It is preferable that the variable magnification optical system satisfy the following conditional expression (11). By ensuring that the corresponding value of conditional expression (11) is not below the lower limit, the range of motion of the second lens group G2 during magnification change will not become too short, making it easy to achieve a high variable magnification ratio. Alternatively, the refractive power of the first lens group G1 will not become too weak, making it easy to achieve both compactness and a high variable magnification ratio. By ensuring that the corresponding value of conditional expression (11) is not above the upper limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position will not become too long, making it possible to prevent the diameter of the first lens group G1 from becoming too large, making it easy to achieve compactness. Alternatively, the refractive power of the first lens group G1 will not become too strong, making it easy to achieve high performance. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (11-1), even more preferable that the following conditional expression (11-2) is satisfied, even more preferable that the following conditional expression (11-3) is satisfied, and even more preferable that the following conditional expression (11-4) is satisfied: 0.2<DDL1STw / f1<0.8 (11) 0.25<DDL1STw / f1<0.7 (11-1) 0.25<DDL1STw / f1<0.65 (11-2) 0.25<DDL1STw / f1<0.6 (11-3) 0.3<DDL1STw / f1<0.55 (11-4)

[0103] If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, it is preferable that the variable magnification optical system satisfy 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, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position does not become too short, making it easy to suppress aberration fluctuations during magnification variation. By ensuring that the corresponding value of conditional expression (12) is not equal to or greater than the upper limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position does not become too long, making it possible to suppress an increase in the diameter of the first lens group G1, and thus facilitating size reduction. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (12-1), it is even more preferable that it satisfy the following conditional expression (12-2), it is even more preferable that it satisfy the following conditional expression (12-3), and it is even more preferable that it satisfy the following conditional expression (12-4). 3<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <9 (12) 3.5<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <8 (12-1) 3.5<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <7.5 (12-2) 3.5<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <7 (12-3) 4<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <6.5 (12-4)

[0104] 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 is easy to suppress various aberrations 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 is easy to shorten the overall length at the wide-angle end. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (13-1), it is even more preferable that it satisfies the following conditional expression (13-2), it is even more preferable that it satisfies the following conditional expression (13-3), and it is even more preferable that it satisfies the following conditional expression (13-4). 3<TLw / fw<8 (13) 3.5<TLw / fw<7.5 (13-1) 3.5<TLw / fw<7 (13-2) 4<TLw / fw<6.5 (13-3) 4<TLw / fw<6 (13-4)

[0105] 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 becomes easy to suppress various aberrations at the telephoto end. By ensuring that the corresponding value of conditional expression (14) is not equal to or greater than the upper limit, it becomes easy to shorten the overall length at the telephoto end. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (14-1), it is even more preferable that it satisfies the following conditional expression (14-2), it is even more preferable that it satisfies the following conditional expression (14-3), and it is even more preferable that it satisfies the following conditional expression (14-4). 1.5<TLt / ft<3 (14) 1.65<TLt / ft<2.85 (14-1) 1.8<TLt / ft<2.7 (14-2) 1.95<TLt / ft<2.7 (14-3) 2.05<TLt / ft<2.55 (14-4)

[0106] 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 equal to or less than the lower limit, the axial light beam ta can be gradually converged toward the image plane Sim at the telephoto end, thereby suppressing the axial chromatic aberration that occurs when the light beam is converged. By ensuring that the corresponding value of conditional expression (15) is not equal to or greater than the upper limit, it becomes easy to shorten the overall length at the telephoto end. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (15-1), it is even more preferable that it satisfy the following conditional expression (15-2), it is even more preferable that it satisfy the following conditional expression (15-3), and it is even more preferable that it satisfy the following conditional expression (15-4). 5<TLt / (ft×tanωt)<11 (15) 5.5<TLt / (ft×tanωt)<10.5 (15-1) 6<TLt / (ft×tanωt)<10 (15-2) 6<TLt / (ft×tanωt)<9 (15-3) 6.5<TLt / (ft×tanωt)<8.5 (15-4)

[0107] It is preferable that the variable magnification optical system satisfy 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, the refractive power of the first lens group G1 does not become too strong, making it easy to suppress aberration fluctuations during magnification variation. By ensuring that the corresponding value of conditional expression (16) is not equal to or greater than the upper limit, the refractive power of the first lens group G1 does not become too weak, making it easy to reduce the size of the first lens group G1. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (16-1), it is even more preferable that it satisfy the following conditional expression (16-2), it is even more preferable that it satisfy the following conditional expression (16-3), and it is even more preferable that it satisfy the following conditional expression (16-4). 3<f1 / fw<7 (16) 3.5<f1 / fw<6.5 (16-1) 3.5<f1 / fw<6 (16-2) 4<f1 / fw<6 (16-3) 4<f1 / fw<5.5 (16-4)

[0108] When the focal length of the second lens group G2 is f2, it is preferable that the variable magnification optical system satisfy the following conditional expression (17). By ensuring that the corresponding value of conditional expression (17) is not equal to or less than the lower limit, the refractive power of the second lens group G2 does not become too weak, making it easy to suppress the amount of movement of the second lens group G2 during variable magnification. By ensuring that the corresponding value of conditional expression (17) is not equal to or greater than the upper limit, the refractive power of the first lens group G1 does not become too weak, making it easy to suppress an increase in the size of the first lens group G1. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (17-1), it is even more preferable that it satisfy the following conditional expression (17-2), it is even more preferable that it satisfy the following conditional expression (17-3), and it is even more preferable that it satisfy the following conditional expression (17-4). 3<f1 / (-f2)<9 (17) 3.5<f1 / (-f2)<8.5 (17-1) 4<f1 / (-f2)<8 (17-2) 4<f1 / (-f2)<7.5 (17-3) 4.5<f1 / (-f2)<7 (17-4)

[0109] It is preferable that the variable magnification optical system satisfies the following conditional expression (18). Ensuring that the corresponding value of conditional expression (18) is not equal to or less than the lower limit is advantageous for improving performance. Ensuring that the corresponding value of conditional expression (18) is not equal to or greater than the upper limit prevents the refractive power of the first lens group G1 from becoming too weak, making it easier to reduce the size of the first lens group G1. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (18-1), it is even more preferable that it satisfies the following conditional expression (18-2), it is even more preferable that it satisfies the following conditional expression (18-3), and it is even more preferable that it satisfies the following conditional expression (18-4). 2<f1 / (ft / Fnot)<7 (18) 2.5<f1 / (ft / Fnot)<6.5 (18-1) 3<f1 / (ft / Fnot)<6.5 (18-2) 3.5<f1 / (ft / Fnot)<6 (18-3) 4<f1 / (ft / Fnot)<6 (18-4)

[0110] It is preferable that the variable magnification optical system satisfies the following conditional expression (19). By ensuring that the corresponding value of conditional expression (19) is not below the lower limit, the refractive power of the first lens group G1 does not become too strong, making it easier to suppress aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (19) is not above the upper limit, the refractive power of the first lens group G1 does not become too weak, which is advantageous for size reduction. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (19-1), even more preferable that it satisfies the following conditional expression (19-2), even more preferable that it satisfies the following conditional expression (19-3), and even more preferable that it satisfies the following conditional expression (19-4): 1.8<f1 / (fw×ft) １／２ <4.2 (19) 1.9<f1 / (fw×ft) １／２ <4.1 (19-1) 2<f1 / (fw×ft) １／２ <4 (19-2) 2.1<f1 / (fw×ft) １／２ <3.9 (19-3) 2.2<f1 / (fw×ft) １／２ <3.8 (19-4)

[0111] It is preferable that the variable magnification optical system satisfy the following conditional expression (20). Here, Denw is the distance on the optical axis from the object-side surface of the first lens to the paraxial entrance pupil position Penw when focused on an object at infinity at the wide-angle end. As an example, FIG. 2 shows the above distance Denw and the paraxial entrance pupil position Penw. By ensuring that the corresponding value of conditional expression (20) is not equal to or less than the lower limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position does not become too short, making it easy to suppress aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (20) is not equal to or greater than the upper limit, the distance from the object-side surface of the first lens on the wide-angle side to the entrance pupil position does not become too long, making it possible to suppress an increase in the diameter of the first lens group G1, thereby facilitating size reduction. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (20-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (20-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (20-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (20-4): 2<Denw / {(fw×tanωw)×log(ft / fw)}<4.5 (20) 2.2<Denw / {(fw×tanωw)×log(ft / fw)}<4.2 (20-1) 2.4<Denw / {(fw×tanωw)×log(ft / fw)}<3.9 (20-1) 2.4<Denw / {(fw×tanωw)×log(ft / fw)}<3.6 (20-1) 2.6<Denw / {(fw×tanωw)×log(ft / fw)}<3.3 (20-1)

[0112] 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, the distance from the object-side surface of the first lens to the entrance pupil position does not become too short, making it easy to suppress aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (21) is not equal to or greater than the upper limit, the distance from the object-side surface of the first lens to the entrance pupil position does not become too long, making it possible to prevent the diameter of the first lens group G1 from becoming too large, and thus facilitating size reduction. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (21-1), it is even more preferable that it satisfies the following conditional expression (21-2), it is even more preferable that it satisfies the following conditional expression (21-3), and it is even more preferable that it satisfies the following conditional expression (21-4): 0.5<Denw / (fw×ft) １／２ <1 (21) 0.55<Denw / (fw×ft) １／２ <0.95 (21-1) 0.6<Denw / (fw×ft) １／２ <0.9 (21-2) 0.65<Denw / (fw×ft) １／２ <0.85 (21-3) 0.7<Denw / (fw×ft) １／２ <0.85 (21-4)

[0113] When the center thickness of the first lens is d1, it is preferable that the variable magnification optical system satisfy the following conditional expression (22). Ensuring that the corresponding value of conditional expression (22) is not equal to or less than the lower limit thereof is advantageous for ensuring the strength of the first lens. Ensuring that the corresponding value of conditional expression (22) is not equal to or greater than the upper limit thereof is advantageous for reducing the weight of the first lens group G1. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (22-1), it is even more preferable that it satisfy the following conditional expression (22-2), it is even more preferable that it satisfy the following conditional expression (22-3), and it is even more preferable that it satisfy the following conditional expression (22-4). 0.04<d1 / (Denw×tanωw)<0.09 (22) 0.045<d1 / (Denw×tanωw)<0.085 (22-1) 0.05<d1 / (Denw×tanωw)<0.085 (22-2) 0.055<d1 / (Denw×tanωw)<0.08 (22-3) 0.055<d1 / (Denw×tanωw)<0.075 (22-4)

[0114] It is preferable that the variable magnification optical system satisfy the following conditional expression (23). Here, Dexw is the distance on the optical axis from the image plane Sim to the paraxial exit pupil position Pexw when focused on an object at infinity at the wide-angle end. The sign of Dexw, with respect to the image plane Sim, is positive for distances closer to the image and negative for distances closer to the object. Furthermore, if an optical element without refractive power is disposed between the image plane Sim and the paraxial exit pupil position Pexw, Dexw is calculated using the air-equivalent distance for that optical element. As an example, FIG. 2 shows the above-mentioned distance Dexw and the paraxial exit pupil position Pexw. By ensuring that the corresponding value of conditional expression (23) is not equal to or less than the lower limit, it is easy to shorten the overall length, which is advantageous for miniaturization. By ensuring that the corresponding value of conditional expression (23) is not equal to or greater than the upper limit, it is easy to reduce the angle of the off-axial chief ray incident on the image plane Sim, which is advantageous for ensuring peripheral light intensity. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (23-1), it is even more preferable that the following conditional expression (23-2) is satisfied, it is even more preferable that the following conditional expression (23-3) is satisfied, and it is even more preferable that the following conditional expression (23-4) is satisfied: -0.65<fw / Dexw<-0.2 (23) -0.6<fw / Dexw<-0.2 (23-1) -0.55<fw / Dexw<-0.2 (23-2) -0.55<fw / Dexw<-0.25 (23-3) -0.5<fw / Dexw<-0.3 (23-4)

[0115] It is preferable that the variable magnification optical system satisfy the following conditional expression (24). Here, the effective diameter of the object-side surface of the first lens is designated as EDf. The effective diameter of the lens surface of the final lens group GE closest to the image is designated as EDr. By ensuring that the corresponding value of conditional expression (24) is not equal to or less than the lower limit, the diameter of the first lens does not become too small, making it easy to ensure the peripheral illumination ratio at the maximum image height. Alternatively, the refractive power of the first lens group G1 does not become too strong due to the reduction in the diameter of the first lens, making it easy to suppress aberration fluctuations during magnification. By ensuring that the corresponding value of conditional expression (24) is not equal to or greater than the upper limit, the diameter of the first lens does not become too large, making it easy to achieve compactness. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (24-1), it is even more preferable that it satisfy the following conditional expression (24-2), it is even more preferable that it satisfy the following conditional expression (24-3), and it is even more preferable that it satisfy the following conditional expression (24-4). 1.5<EDf / EDr<3 (24) 1.6<EDf / EDr<2.8 (24-1) 1.6<EDf / EDr<2.6 (24-2) 1.7<EDf / EDr<2.4 (24-3) 1.8<EDf / EDr<2.2 (24-4)

[0116] In this specification, the "effective diameter" of a lens surface is defined as twice the distance from the point of intersection of the outermost ray and the lens surface, among the rays that enter the lens surface from the object side and emerge toward the image side, to the optical axis Z. Here, "outside" refers to the radially outward direction centered on the optical axis Z, i.e., the side away from the optical axis Z. The "outside ray" is determined taking into account the entire range of magnification.

[0117] For explanatory purposes, FIG. 3 shows an example of the effective diameter ED. In FIG. 3, the left side is the object side and the right side is the image side. FIG. 3 shows an on-axis light beam Xa and an off-axis light beam Xb passing through the lens Lx. In the example of FIG. 3, ray Xb1, which is the upper ray of the off-axis light beam Xb, is the outermost ray. Therefore, in the example of FIG. 3, the effective diameter ED of the object-side surface of the lens Lx is twice the distance from the intersection of the object-side surface of the lens Lx and ray Xb1 to the optical axis Z. Furthermore, the position of the intersection of the outermost ray and the lens surface is the position Px of the maximum effective diameter. Note that in the example of FIG. 3, 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.

[0118] It is preferable that the variable magnification optical system satisfies the following conditional expression (25). By ensuring that the corresponding value of conditional expression (25) is not equal to or less than the lower limit, it is advantageous for shortening the overall length. By ensuring that the corresponding value of conditional expression (25) is not equal to or greater than the upper limit, it is easy to reduce the diameter of the first lens. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (25-1), it is even more preferable that it satisfies the following conditional expression (25-2), it is even more preferable that it satisfies the following conditional expression (25-3), and it is even more preferable that it satisfies the following conditional expression (25-4). 0.35<EDf / TLw<0.65 (25) 0.38<EDf / TLw<0.62 (25-1) 0.41<EDf / TLw<0.59 (25-2) 0.41<EDf / TLw<0.56 (25-3) 0.44<EDf / TLw<0.53 (25-4)

[0119] 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 below the lower limit, the variable magnification ratio does not become too low, and thus a useful value as a variable magnification optical system can be obtained. By ensuring that the corresponding value of conditional expression (26) is not above the upper limit, the variable magnification ratio does not become too high, and this is advantageous for miniaturization. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (26-1), even more preferable that it satisfies the following conditional expression (26-2), even more preferable that it satisfies the following conditional expression (26-3), and even more preferable that it satisfies the following conditional expression (26-4). 2.2<ft / fw<4.8 (26) 2.35<ft / fw<4.4 (26-1) 2.35<ft / fw<4 (26-1) 2.5<ft / fw<3.6 (26-1) 2.5<ft / fw<3.2 (26-1)

[0120] When the refractive index of the first lens with respect to the d-line is NdL1, it is preferable that the variable magnification optical system satisfy the following conditional expression (27). By ensuring that the corresponding value of conditional expression (27) is not below the lower limit, the absolute value of the radius of curvature of the first lens will not become too small in order to ensure the refractive power of the first lens necessary to correct aberrations generated by the positive lens constituting the first lens group G1. As a result, an increase in high-order spherical aberration at the telephoto end can be suppressed, which is advantageous for improving performance. Alternatively, by ensuring that the corresponding value of conditional expression (27) is not below the lower limit, the refractive power of the first lens will not become too weak and its outer diameter will not become too large, and therefore the refractive power of the positive lens in the first lens group G1 will not become too weak and its outer diameter will not become too large. This facilitates the miniaturization of the first lens group G1. Regarding the upper limit of conditional expression (27), since optical materials generally have higher specific gravity and smaller Abbe number as their refractive index increases, by ensuring that the corresponding value of conditional expression (27) does not exceed the upper limit, it is possible to suppress an increase in the weight of the first lens having a large lens diameter, thereby facilitating weight reduction. Furthermore, it becomes easier to correct chromatic aberration of magnification at the wide-angle end. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (27-1), even more preferable that it satisfies the following conditional expression (27-2), even more preferable that it satisfies the following conditional expression (27-3), and even more preferable that it satisfies the following conditional expression (27-4): 1.8<NdL1<2.01 (27) 1.8<NdL1<1.96 (27-1) 1.8<NdL1<1.91 (27-2) 1.84<NdL1<1.96 (27-3) 1.84<NdL1<1.91 (27-4)

[0121] When the Abbe number of the first lens based on the d-line is νdL1, it is preferable that the variable magnification optical system satisfy the following conditional expression (28). By ensuring that the corresponding value of conditional expression (28) is not equal to or less than the lower limit, it is possible to prevent overcorrection of axial chromatic aberration at the telephoto end. Furthermore, since the difference in Abbe numbers between the positive lens and the negative lens constituting the first lens group G1 does not become too large, the refractive power of the first lens does not become too weak. As a result, it is easy to correct chromatic aberration of magnification at the wide-angle end. By ensuring that the corresponding value of conditional expression (28) is not equal to or greater than the upper limit, it is possible to prevent undercorrection of axial chromatic aberration at the telephoto end. Furthermore, since the difference in Abbe numbers between the positive lens and the negative lens constituting the first lens group G1 does not become too small, the refractive power of each lens constituting the first lens group G1 does not become too strong. As a result, it is possible to prevent an increase in high-order spherical aberration at the telephoto end, which facilitates high performance. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (28-1), it is even more preferable that the following conditional expression (28-2) is satisfied, it is even more preferable that the following conditional expression (28-3) is satisfied, and it is even more preferable that the following conditional expression (28-4) is satisfied: 15<νdL1<45 (28) 15<νdL1<40 (28-1) 15<νdL1<36 (28-2) 18<νdL1<36 (28-3) 20<νdL1<36 (28-4)

[0122] It is preferable that the variable magnification optical system satisfy the following conditional expression (29). By ensuring that the corresponding value of conditional expression (29) is not equal to or less than the lower limit, it is possible to select a material other than a material with a low refractive index and a low Abbe number, thereby facilitating correction of chromatic aberration of magnification at the wide-angle end. By ensuring that the corresponding value of conditional expression (29) is not equal to or greater than the upper limit, it is possible to select a material other than a material with a high refractive index and a high Abbe number, thereby allowing the selection of a material with a low specific gravity, thereby facilitating weight reduction. Furthermore, since the difference in Abbe number between the positive lens and the negative lens constituting the first lens group G1 does not become too small, the refractive power of each lens constituting the first lens group G1 does not become too strong. As a result, higher-order aberrations of spherical aberration at the telephoto end can be suppressed. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (29-1), it is even more preferable that it satisfy the following conditional expression (29-2), it is even more preferable that it satisfy the following conditional expression (29-3), and it is even more preferable that it satisfy the following conditional expression (29-4). 2<NdL1+0.01×νdL1<2.5 (29) 2<NdL1+0.01×νdL1<2.35 (29-1) 2.05<NdL1+0.01×νdL1<2.35 (29-2) 2<NdL1+0.01×νdL1<2.2 (29-3) 2.05<NdL1+0.01×νdL1<2.2 (29-4)

[0123] It is preferable that the variable magnification optical system simultaneously satisfy conditional expressions (27), (28), and (29). It is more preferable that the variable magnification optical system simultaneously satisfy conditional expressions (27), (28), and (29), and then satisfy at least one of conditional expressions (27-1), (27-2), (27-3), (27-4), (28-1), (28-2), (28-3), (28-4), (29-1), (29-2), (29-3), and (29-4).

[0124] When the refractive index of the second lens with respect to the d-line is NdL2, it is preferable that the variable magnification optical system satisfy the following conditional expression (30). By ensuring that the corresponding value of conditional expression (30) is not below the lower limit, the absolute value of the radius of curvature of the positive lens constituting the first lens group G1 does not have to be small in order to ensure the positive refractive power necessary for miniaturizing the first lens group G1. As a result, an increase in high-order spherical aberration at the telephoto end can be suppressed, making it easy to improve performance. Alternatively, it becomes easy to miniaturize the first lens group G1. Regarding the upper limit of conditional expression (30), since the specific gravity of optical materials generally increases as the refractive index increases, by ensuring that the corresponding value of conditional expression (30) is not above the upper limit, an increase in the weight of the lens can be suppressed, making it easy to reduce the weight. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (30-1), it is even more preferable that the following conditional expression (30-2) is satisfied, it is even more preferable that the following conditional expression (30-3) is satisfied, and it is even more preferable that the following conditional expression (30-4) is satisfied: 1.43<NdL2<1.81 (30) 1.43<NdL2<1.76 (30-1) 1.43<NdL2<1.71 (30-2) 1.43<NdL2<1.66 (30-3) 1.47<NdL2<1.61 (30-4)

[0125] When the Abbe number of the second lens based on the d-line is νdL2, it is preferable that the variable magnification optical system satisfy the following conditional expression (31). By ensuring that the corresponding value of conditional expression (31) is not below the lower limit, it is possible to prevent axial chromatic aberration at the telephoto end from being undercorrected. Alternatively, since the difference in Abbe numbers between the positive lens and the negative lens constituting the first lens group G1 does not become too small, the refractive power of each lens constituting the first lens group G1 does not become too strong. As a result, it is possible to prevent an increase in high-order spherical aberration at the telephoto end, making it easy to achieve high performance. By ensuring that the corresponding value of conditional expression (31) is not above the upper limit, it is possible to prevent axial chromatic aberration at the telephoto end from being overcorrected. Alternatively, since the difference in Abbe numbers between the positive lens and the negative lens constituting the first lens group G1 does not become too large, the refractive power of the first lens does not become too weak. As a result, it is easy to correct chromatic aberration of magnification at the wide-angle end. To obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (31-1), it is even more preferable that the following conditional expression (31-2) is satisfied, it is even more preferable that the following conditional expression (31-3) is satisfied, and it is even more preferable that the following conditional expression (31-4) is satisfied: 45<νdL2<96 (31) 45<νdL2<82 (31-1) 45<νdL2<77 (31-2) 45<νdL2<71 (31-3) 49<νdL2<71 (31-4)

[0126] It is preferable that the variable magnification optical system satisfy the following conditional expression (32). By ensuring that the corresponding value of conditional expression (32) is not equal to or less than the lower limit, it is possible to select a material other than a material with a low refractive index and a low Abbe number, thereby suppressing an increase in high-order aberrations of spherical aberration at the telephoto end, and thereby facilitating high performance. Alternatively, it is possible to prevent axial chromatic aberration at the telephoto end from being undercorrected. By ensuring that the corresponding value of conditional expression (32) is not equal to or greater than the upper limit, it is possible to select a material other than a material with a high refractive index and a high Abbe number, thereby enabling a material with a low specific gravity to be selected, and thereby facilitating weight reduction. Alternatively, it is possible to prevent axial chromatic aberration at the telephoto end from being overcorrected. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfy the following conditional expression (32-1), it is even more preferable that it satisfy the following conditional expression (32-2), it is even more preferable that it satisfy the following conditional expression (32-3), and it is even more preferable that it satisfy the following conditional expression (32-4). 2<NdL2+0.01×νdL2<2.5 (32) 2.05<NdL2+0.01×νdL2<2.45 (32-1) 2.1<NdL2+0.01×νdL2<2.4 (32-2) 2.1<NdL2+0.01×νdL2<2.35 (32-3) 2.15<NdL2+0.01×νdL2<2.35 (32-4)

[0127] It is preferable that the variable magnification optical system simultaneously satisfy conditional expressions (30), (31), and (32). It is more preferable that the variable magnification optical system simultaneously satisfy conditional expressions (30), (31), and (32), and then satisfy at least one of conditional expressions (30-1), (30-2), (30-3), (30-4), (31-1), (31-2), (31-3), (31-4), (32-1), (32-2), (32-3), and (32-4).

[0128] It is preferable that a variable magnification optical system, in a configuration including at least one focusing group that moves during magnification variation and focusing, satisfy the following conditional expression (33). Here, the focal length of the focusing group having the smallest absolute focal length value among the focusing groups included in the variable magnification optical system is designated as ffoc. The focal length of the middle group GM when focused on an object at infinity at the telephoto end is designated as fMt. 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 focusing group does not become too strong, thereby preventing excessive aberration correction during focusing. 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 focusing group does not become too weak, thereby preventing insufficient aberration correction during focusing. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (33-1), it is even more preferable that the following conditional expression (33-2) is satisfied, it is even more preferable that the following conditional expression (33-3) is satisfied, and it is even more preferable that the following conditional expression (33-4) is satisfied: 0.3<|ffoc / fMt|<4 (33) 0.35<|ffoc / fMt|<3.5 (33-1) 0.4<|ffoc / fMt|<3 (33-2) 0.45<|ffoc / fMt|<2.5 (33-3) 0.5<|ffoc / fMt|<2 (33-4)

[0129] It is preferable that a variable magnification optical system, in a configuration including at least one focusing group that moves during magnification variation and focusing, satisfy the following conditional expression (34). Here, βft is the lateral magnification of the focusing group with the largest absolute focal length among the focusing groups included in the variable magnification optical system when focused on an object at infinity at the telephoto end. βfRt is the combined lateral magnification of all lenses located on the image side of the focusing group with the largest absolute focal length when focused on an object at infinity at the telephoto end. By ensuring that the value corresponding to conditional expression (34) is not equal to or less than the lower limit, the ratio of the amount of movement of the image plane to the unit amount of movement of the focusing group does not become too small, so the amount of movement of the focusing group during focusing does not become too large, which is advantageous for achieving both high performance and compactness. By ensuring that the value corresponding to conditional expression (34) is not equal to or greater than the upper limit, the ratio of the amount of movement of the image plane to the unit amount of movement of the focusing group does not become too large, which is advantageous for achieving both manufacturability and compactness. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (34-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (34-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (34-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (34-4): 1<|(1-βft ２ ) × βfRt ２ |<8 (34) 1.3<|(1-βft ２ ) × βfRt ２ |<7 (34-1) 1.5<|(1-βft ２ ) × βfRt ２ |<6 (34-2) 1.7<|(1-βft ２ ) × βfRt ２ |<5 (34-3) 1.9<|(1-βft ２ ) × βfRt ２ |<4(34-4)

[0130] In a configuration in which the focusing group consists of one positive lens and two negative lenses, and the negative lens closest to the image side of the focusing group is an aspherical lens, it is preferable that the variable magnification optical system satisfy the following conditional expression (35) for this aspherical lens. Here, the paraxial radius of curvature of the object-side surface of the aspherical lens is defined as Rcnf. The paraxial radius of curvature of the image-side surface of the aspherical lens is defined as Rcnr. The radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Rynf. The radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Rynr. By ensuring that the corresponding value of conditional expression (35) is not below the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion. By ensuring that the corresponding value of conditional expression (35) is not equal to or greater than the upper limit, the refractive power on the peripheral side of the lens does not become too weak, which is advantageous for correcting curvature of field and astigmatism that occur due to off-axial rays on the peripheral side of the lens. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (35-1), even more preferable that it satisfies the following conditional expression (35-2), even more preferable that it satisfies the following conditional expression (35-3), and even more preferable that it satisfies the following conditional expression (35-4). 0.1<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<3 (35) 0.15(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<2.5 (35-1) 0.2<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<2 (35-2) 0.25<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<1.5 (35-3) 0.3<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<1 (35-4)

[0131] In a configuration in which the focusing group consists of one negative lens and two positive lenses, and the positive lens closest to the image side of the focusing group is an aspherical lens, it is preferable that the variable magnification optical system satisfy the following conditional expression (36) for this aspherical lens. Here, the paraxial radius of curvature of the object-side surface of the aspherical lens is defined as Rcpf. The paraxial radius of curvature of the image-side surface of the aspherical lens is defined as Rcpr. The radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Rypf. The radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Rypr. By ensuring that the corresponding value of conditional expression (36) is not below the lower limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axial rays on the peripheral side of the lens. By ensuring that the corresponding value of conditional expression (36) is not equal to or greater than the upper limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (36-1), even more preferable that it satisfies the following conditional expression (36-2), even more preferable that it satisfies the following conditional expression (36-3), and even more preferable that it satisfies the following conditional expression (36-4). -120<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-3 (36) -100<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-6 (36-1) -80<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-9 (36-2) -60<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-12 (36-3) -40<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-15 (36-4)

[0132] In a configuration in which the focusing group is composed of one negative lens, and the negative lens of the focusing group is an aspherical lens, it is preferable that the variable magnification optical system satisfies the following conditional expression (37) for this aspherical lens. Here, the paraxial radius of curvature of the object-side surface of the aspherical lens is defined as Rcsnf. The paraxial radius of curvature of the image-side surface of the aspherical lens is defined as Rcsnr. The radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Rysnf. The radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Rysnr. By ensuring that the corresponding value of conditional expression (37) is not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion. By ensuring that the corresponding value of conditional expression (37) is not equal to or greater than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting curvature of field and astigmatism caused by off-axial rays on the peripheral side of the lens. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (37-1), it is even more preferable that it satisfies the following conditional expression (37-2), it is even more preferable that it satisfies the following conditional expression (37-3), and it is even more preferable that it satisfies the following conditional expression (37-4). 0.1<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<3.5 (37) 0.2<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<3 (37-1) 0.3<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<2.5 (37-2) 0.4<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<2 (37-3) 0.5<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<1.5 (37-4)

[0133] In a configuration in which the image-side focusing group consists of one positive lens, and the positive lens of the image-side focusing group is an aspherical lens, it is preferable that the variable magnification optical system satisfies the following conditional expression (38) for this aspherical lens. Here, the paraxial radius of curvature of the object-side surface of the aspherical lens is defined as Rcipf. The paraxial radius of curvature of the image-side surface of the aspherical lens is defined as Rcipr. The radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Ryipf. The radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Ryipr. By ensuring that the corresponding value of conditional expression (38) is not below the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion. By ensuring that the corresponding value of conditional expression (38) is not equal to or greater than the upper limit, the refractive power on the peripheral side of the lens does not become too weak, which is advantageous for correcting curvature of field and astigmatism that occur due to off-axial rays on the peripheral side of the lens. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (38-1), even more preferable that it satisfies the following conditional expression (38-2), even more preferable that it satisfies the following conditional expression (38-3), and even more preferable that it satisfies the following conditional expression (38-4). 1<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<100 (38) 1.5<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<80 (38-1) 2<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<60 (38-2) 2.5<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<40 (38-3) 3<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<20 (38-4)

[0134] In a configuration in which the image-side focusing group is composed of one negative lens, and the negative lens of the image-side focusing group is an aspherical lens, it is preferable that the variable magnification optical system satisfies the following conditional expression (39) for this aspherical lens. Here, the paraxial radius of curvature of the object-side surface of the aspherical lens is defined as Rcinf. The paraxial radius of curvature of the image-side surface of the aspherical lens is defined as Rcinr. The radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Ryinf. The radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter is defined as Ryinr. By ensuring that the corresponding value of conditional expression (39) is not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion. By ensuring that the corresponding value of conditional expression (39) is not equal to or greater than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting curvature of field and astigmatism caused by off-axial rays on the peripheral side of the lens. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (39-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (39-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (39-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (39-4): 0.1<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<3.5 (39) 0.2<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<3 (39-1) 0.3<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<2.5 (39-2) 0.4<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<2 (39-3) 0.5<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<1.5 (39-4)

[0135] In a configuration in which the final lens group GE is composed of a single aspherical positive lens, it is preferable that the variable magnification optical system satisfies the following conditional expression (40) for this aspherical lens. Here, the paraxial radius of curvature of the object-side surface of the aspherical lens is RcEpf. The paraxial radius of curvature of the image-side surface of the aspherical lens is RcEpr. The radius of curvature of the object-side surface of the aspherical lens at the position of the maximum effective diameter is RyEpf. The radius of curvature of the image-side surface of the aspherical lens at the position of the maximum effective diameter is RyEpr. By ensuring that the corresponding value of conditional expression (40) is not equal to or less than the lower limit, the refractive power of the lens on the peripheral side does not become too strong, which is advantageous for suppressing distortion. By ensuring that the corresponding value of conditional expression (40) is not equal to or greater than the upper limit, the refractive power of the lens on the peripheral side does not become too weak, which is advantageous for correcting field curvature and astigmatism caused by off-axial rays on the peripheral side of the lens. In order to obtain better characteristics, it is more preferable that the variable magnification optical system satisfies the following conditional expression (40-1), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (40-2), it is even more preferable that the variable magnification optical system satisfies the following conditional expression (40-3), and it is even more preferable that the variable magnification optical system satisfies the following conditional expression (40-4). 0.1<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<5 (40) 0.2<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<4 (40-1) 0.3<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<3 (40-2) 0.4<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<2 (40-3) 0.5<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<1.5 (40-4)

[0136] 1 is merely an example, and various modifications are possible without departing from the spirit of the technology of the present disclosure. For example, the number of lens groups included in the intermediate group GM and the number of lenses included in each lens group may be different from those in the example of FIG.

[0137] In the example of FIG. 1 , the intermediate group GM is made up of two lens groups, but in the technology of the present disclosure, the intermediate group GM may be configured to be made up of one lens group, three lens groups, four lens groups, or five lens groups.

[0138] The intermediate group GM and the final lens group GE may be configured as described below. Such a configuration is advantageous for suppressing aberration fluctuations during magnification variation. The intermediate group GM may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power, and the final lens group GE has positive refractive power. The intermediate group GM may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group GE has negative refractive power. The intermediate group GM may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group GE has positive refractive power. The intermediate group GM may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group GE may be configured to have negative refractive power.The intermediate group GM may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group GE may be configured to have negative refractive power.The intermediate group GM may be configured to include, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group GE may be configured to have positive refractive power. The intermediate group GM is composed of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group GE may be configured to have negative refractive power.

[0139] The final lens group GE may be configured to move when the magnification is changed, which is advantageous for suppressing aberration fluctuations when the magnification is changed.

[0140] The variable magnification optical system of the present disclosure may be configured to include multiple lens groups that move along the same movement locus when changing magnification from the wide-angle end to the telephoto end. In this case, the lens groups that move along the same movement locus can be driven by a single cam, thereby simplifying the lens group drive mechanism. Note that the above phrase "the same movement locus when changing magnification from the wide-angle end to the telephoto end" means that the movement locus is the same throughout the entire range of magnification from the wide-angle end to the telephoto end.

[0141] The variable magnification optical system of the present disclosure may be a zoom lens or a varifocal lens.

[0142] The above-described preferred and possible configurations can be arbitrarily combined, and are preferably selectively adopted as appropriate according to the required specifications. Note that the conditional expressions that the variable magnification optical system of the present disclosure preferably satisfies are not limited to those written in the form of an expression, but include all conditional expressions obtained by arbitrarily combining the lower and upper limits of the conditional expressions that are deemed to be preferred, more preferred, even more preferred, even more preferred, and even more preferred.

[0143] For example, a first preferred aspect of the variable magnification optical system of the present disclosure is one that comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an intermediate group GM, and a final lens group GE having refractive power, the intermediate group GM being composed of one or more and five or less lens groups, and during magnification variation, the distance between the first lens group G1 and the second lens group G2 changes, the distance between the second lens group G2 and the intermediate group GM changes, and the distance between the intermediate group GM and the final lens group GE changes. and if the intermediate group GM is made up of a plurality of lens groups, the intervals between all of the adjacent lens groups in the intermediate group GM change during zooming. An aperture stop St is disposed between the lens surface of the second lens group G2 closest to the image side and the lens surface of the final lens group GE closest to the object side. The first lens group G1 includes, in succession from the most object side to the image side, a first lens which is a negative lens and a second lens which is a positive lens, and satisfies the above conditional expressions (1), (2), and (3).

[0144] A preferred second aspect of the variable magnification optical system of the present disclosure is the first aspect, further satisfying the above conditional expressions (4), (5), (6), and (7).

[0145] Next, examples of the variable magnification optical system of the present disclosure will be described with reference to the drawings. The reference symbols assigned to the lenses 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.

[0146] [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 first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. During magnification change from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0147] For the variable magnification optical system of Example 1, basic lens data is shown in Table 1, specifications and variable surface spacings are shown in Table 2, and aspherical coefficients are shown in Table 3.

[0148] 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 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 for the d-line of each component element. The νd column shows the Abbe number of each component element based on the d-line. The θgF column shows the partial dispersion ratio between the g-line and F-line of each component element. The ED column shows the effective diameter of each surface.

[0149] 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. Table 1 also shows the aperture stop St, and the surface number column for the surface corresponding to the aperture stop St is entered with the surface number and the phrase (St). The value in the bottom column of the surface spacing column in the table is the spacing between the surface closest to the image side in the table and the image plane Sim. The symbol DD[ ] is used for variable surface spacing, and the surface number on the object side of this spacing is entered in the brackets [ ] in the surface spacing column.

[0150] Table 2 shows the zoom ratio Zr, focal length f, maximum F-number FNo., maximum full angle of view 2ω, and variable surface spacing based on the d-line. When the zoom 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 column labeled "Wide" shows values ​​for the wide-angle end state, the column labeled "Middle" shows values ​​for the intermediate focal length state, and the column labeled "Tele" shows values ​​for the telephoto end state.

[0151] 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 listed in the column for the radius of curvature of the aspherical surface. In Table 3, the Sn row shows the surface numbers of aspherical surfaces, and the KA and Am rows show 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 eighth surface of Example 1, m = 3, 4, 5, 6, 7, 8, 9, 10. 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 sum over m.

[0152] 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.

[0153]

[0154]

[0155]

[0156] FIG. 4 shows aberration diagrams of the variable magnification optical system of Example 1 when focused on an object at infinity. In FIG. 4, spherical aberration, astigmatism, distortion, and lateral chromatic aberration are shown, from left to right. In FIG. 4, the upper row labeled "Wide" shows aberrations in the wide-angle end state, the middle row labeled "Middle" shows aberrations in the intermediate focal length state, and the lower row labeled "Tele" shows aberrations in the telephoto end state. 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 =.

[0157] 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.

[0158] [Example 2] The configuration and movement locus of the variable magnification optical system of Example 2 are shown in Figure 5. The variable magnification optical system of Example 2 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0159] The first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0160] For the variable magnification optical system of Example 2, basic lens data is shown in Table 4, specifications and variable surface spacings are shown in Table 5, aspherical coefficients are shown in Table 6, and aberration diagrams are shown in FIG.

[0161]

[0162]

[0163]

[0164] [Example 3] The configuration and movement locus of the variable magnification optical system of Example 3 are shown in Figure 7. The variable magnification optical system of Example 3 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0165] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0166] For the variable magnification optical system of Example 3, basic lens data is shown in Table 7, specifications and variable surface spacing are shown in Table 8, aspherical coefficients are shown in Table 9, and aberration diagrams are shown in FIG.

[0167]

[0168]

[0169]

[0170] [Example 4] The configuration and movement locus of the variable magnification optical system of Example 4 are shown in Figure 9. The variable magnification optical system of Example 4 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0171] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0172] For the variable magnification optical system of Example 4, basic lens data is shown in Table 10, specifications and variable surface spacings are shown in Table 11, aspherical coefficients are shown in Table 12, and aberration diagrams are shown in FIG.

[0173]

[0174]

[0175]

[0176] [Example 5] The configuration and movement locus of the variable magnification optical system of Example 5 are shown in Figure 11. The variable magnification optical system of Example 5 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0177] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0178] For the variable magnification optical system of Example 5, basic lens data is shown in Table 13, specifications and variable surface spacings are shown in Table 14, aspherical coefficients are shown in Table 15, and aberration diagrams are shown in FIG.

[0179]

[0180]

[0181]

[0182] [Example 6] The configuration and movement locus of the variable magnification optical system of Example 6 are shown in Figure 13. The variable magnification optical system of Example 6 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0183] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0184] For the variable magnification optical system of Example 6, basic lens data is shown in Table 16, specifications and variable surface spacings are shown in Table 17, aspherical coefficients are shown in Table 18, and aberration diagrams are shown in FIG.

[0185]

[0186]

[0187]

[0188] [Example 7] The configuration and movement locus of the variable magnification optical system of Example 7 are shown in Figure 15. The variable magnification optical system of Example 7 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0189] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0190] For the variable magnification optical system of Example 7, basic lens data is shown in Table 19, specifications and variable surface spacings are shown in Table 20, aspherical coefficients are shown in Table 21, and aberration diagrams are shown in FIG.

[0191]

[0192]

[0193]

[0194] [Example 8] The configuration and movement locus of the variable magnification optical system of Example 8 are shown in Figure 17. The variable magnification optical system of Example 8 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. When varying magnification from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0195] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 and L42, in order from the object side to the image side. The fifth lens group G5 consists of a single lens, L51.

[0196] For the variable magnification optical system of Example 8, basic lens data is shown in Table 22, specifications and variable surface spacing are shown in Table 23, aspherical coefficients are shown in Table 24, and aberration diagrams are shown in FIG.

[0197]

[0198]

[0199]

[0200] Example 9 The configuration and movement locus of the variable magnification optical system of Example 9 are shown in Figure 19. The variable magnification optical system of Example 9 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM comprises the third lens group G3 and the fourth lens group G4. The final lens group GE comprises the fifth lens group G5. During magnification change from the wide-angle end to the telephoto end, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 move along the optical axis Z while changing the spacing between adjacent lens groups, and the fifth lens group G5 is fixed with respect to the image plane Sim. The focusing group is made up of the fourth lens group G4, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0201] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and six lenses, L31 to L36, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of one lens, L51.

[0202] For the variable magnification optical system of Example 9, basic lens data is shown in Table 25, specifications and variable surface spacing are shown in Table 26, aspherical coefficients are shown in Table 27, and various aberration diagrams are shown in FIG.

[0203]

[0204]

[0205]

[0206] [Example 10] The configuration and movement locus of the variable magnification optical system of Example 10 are shown in Figure 21. The variable magnification optical system of Example 10 consists, in order from the object side to the image side, of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. The middle group GM consists of the third lens group G3 and the fourth lens group G4. The final lens group GE consists of the fifth lens group G5. When varying 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 fourth lens group G4, and when focusing from an object at infinity to a closest object, the focusing group moves toward the image side.

[0207] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and five lenses, L31 to L35, in order from the object side to the image side. The fourth lens group G4 consists of one lens, L41. The fifth lens group G5 consists of three lenses, L51 to L53, in order from the object side to the image side.

[0208] For the variable magnification optical system of Example 10, basic lens data is shown in Table 28, specifications and variable surface spacings are shown in Table 29, aspherical coefficients are shown in Table 30, and various aberration diagrams are shown in FIG.

[0209]

[0210]

[0211]

[0212] [Example 11] The configuration and movement locus of the variable magnification optical system of Example 11 are shown in Figure 23. The variable magnification optical system of Example 11 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE comprises the seventh lens group G7. When varying 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 is made up of the fifth lens group G5, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0213] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and three lenses, L31 to L33, in order from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 and L42, in order from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The sixth lens group G6 consists of two lenses, L61 and L62, in order from the object side to the image side. The seventh lens group G7 consists of one lens, L71.

[0214] For the variable magnification optical system of Example 11, basic lens data is shown in Table 31, specifications and variable surface spacings are shown in Table 32, aspherical coefficients are shown in Table 33, and various aberration diagrams are shown in FIG.

[0215]

[0216]

[0217]

[0218] [Example 12] The configuration and movement locus of the variable magnification optical system of Example 12 are shown in Figure 25. The variable magnification optical system of Example 12 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE comprises the seventh lens group G7. When varying 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. When varying magnification from the wide-angle end to the telephoto end, the fourth lens group G4 and the seventh lens group G7 move along the same movement locus. When focusing, the fifth lens group G5 and the sixth lens group G6 move while changing the distance between them. The object-side focusing group consists of the fifth lens group G5, and the image-side focusing group consists of the sixth lens group G6. When focusing from an object at infinity to the closest object, the object-side focusing group and the image-side focusing group move toward the object side.

[0219] The first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side. The third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 to L42, from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 to L52, from the object side to the image side. The sixth lens group G6 consists of one lens, L61. The seventh lens group G7 consists of three lenses, L71 to L73, from the object side to the image side.

[0220] For the variable magnification optical system of Example 12, basic lens data is shown in Table 34, specifications and variable surface spacings are shown in Table 35, aspherical coefficients are shown in Table 36, and various aberration diagrams are shown in FIG.

[0221]

[0222]

[0223]

[0224] [Example 13] The configuration and movement locus of the variable magnification optical system of Example 13 are shown in Figure 27. The variable magnification optical system of Example 13 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE comprises the seventh lens group G7. When varying 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. During focusing, the fifth lens group G5 and the sixth lens group G6 move while changing the distance between them. The object-side focusing group consists of the fifth lens group G5, and the image-side focusing group consists of the sixth lens group G6. During focusing from an object at infinity to the closest object, the object-side focusing group and the image-side focusing group move toward the object side.

[0225] The first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side. The third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 to L42, from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 to L52, from the object side to the image side. The sixth lens group G6 consists of one lens, L61. The seventh lens group G7 consists of three lenses, L71 to L73, from the object side to the image side.

[0226] For the variable magnification optical system of Example 13, basic lens data is shown in Table 37, specifications and variable surface spacings are shown in Table 38, aspherical coefficients are shown in Table 39, and various aberration diagrams are shown in FIG.

[0227]

[0228]

[0229]

[0230] [Example 14] The configuration and movement locus of the variable magnification optical system of Example 14 are shown in Figure 29. The variable magnification optical system of Example 14 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, a sixth lens group G6 having positive refractive power, and a seventh lens group G7 having negative refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE comprises the seventh lens group G7. When varying 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. During focusing, the fifth lens group G5 and the sixth lens group G6 move while changing the distance between them. The object-side focusing group consists of the fifth lens group G5, and the image-side focusing group consists of the sixth lens group G6. During focusing from an object at infinity to the closest object, the object-side focusing group and the image-side focusing group move toward the object side.

[0231] The first lens group G1 consists of three lenses, L11 to L13, from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, from the object side to the image side. The third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 to L42, from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 to L52, from the object side to the image side. The sixth lens group G6 consists of one lens, L61. The seventh lens group G7 consists of three lenses, L71 to L73, from the object side to the image side.

[0232] For the variable magnification optical system of Example 14, basic lens data is shown in Table 40, specifications and variable surface spacings are shown in Table 41, aspherical coefficients are shown in Table 42, and various aberration diagrams are shown in FIG.

[0233]

[0234]

[0235]

[0236] [Example 15] The configuration and movement locus of the variable magnification optical system of Example 15 are shown in Figure 31. The variable magnification optical system of Example 15 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G6 having negative refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE comprises the sixth lens group G6. When varying 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 comprises the fifth lens group G5, and when focusing from an object at infinity to a closest object, the focusing group moves toward the object side.

[0237] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 to L42, in order from the object side to the image side. The fifth lens group G5 consists of three lenses, L51 to L53, in order from the object side to the image side. The sixth lens group G6 consists of three lenses, L61 to L63, in order from the object side to the image side.

[0238] For the variable magnification optical system of Example 15, basic lens data is shown in Table 43, specifications and variable surface spacings are shown in Table 44, aspherical coefficients are shown in Table 45, and various aberration diagrams are shown in FIG.

[0239]

[0240]

[0241]

[0242] [Example 16] The configuration and movement locus of the variable magnification optical system of Example 16 are shown in Figure 33. The variable magnification optical system of Example 16 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE comprises the sixth lens group G6. When varying 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 comprises the fifth lens group G5, and when focusing from an object at infinity to a closest object, the focusing group moves toward the image side.

[0243] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side. The fifth lens group G5 consists of three lenses, L51 to L53, in order from the object side to the image side. The sixth lens group G6 consists of a single lens, L61.

[0244] For the variable magnification optical system of Example 16, basic lens data is shown in Table 46, specifications and variable surface spacing in Table 47, aspherical coefficients in Table 48, and various aberration diagrams in FIG.

[0245]

[0246]

[0247]

[0248] [Example 17] The configuration and movement locus of the variable magnification optical system of Example 17 are shown in Figure 35. The variable magnification optical system of Example 17 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE comprises the seventh lens group G7. When varying 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. When changing magnification from the wide-angle end to the telephoto end, the fourth lens group G4 and the sixth lens group G6 move along the same movement locus. The focusing group is made up of the fifth lens group G5, and when focusing from an object at infinity to the closest object, the focusing group moves toward the image side.

[0249] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and two lenses, L31 to L32, in order from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side. The fifth lens group G5 consists of three lenses, L51 to L53, in order from the object side to the image side. The sixth lens group G6 consists of one lens, L61. The seventh lens group G7 consists of one lens, L71.

[0250] For the variable magnification optical system of Example 17, basic lens data is shown in Table 49, specifications and variable surface spacings are shown in Table 50, aspherical coefficients are shown in Table 51, and various aberration diagrams are shown in FIG.

[0251]

[0252]

[0253]

[0254] [Example 18] The configuration and movement locus of the variable magnification optical system of Example 18 are shown in Figure 37. The variable magnification optical system of Example 18 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6. The final lens group GE comprises the seventh lens group G7. When varying 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. During focusing, the fifth lens group G5 and the sixth lens group G6 move while changing the distance between them. The object-side focusing group consists of the fifth lens group G5, and the image-side focusing group consists of the sixth lens group G6. During focusing from an object at infinity to the closest object, the object-side focusing group and the image-side focusing group move toward the image side.

[0255] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and three lenses, L31 to L33, in order from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 and L52, in order from the object side to the image side. The sixth lens group G6 consists of one lens, L61. The seventh lens group G7 consists of one lens, L71.

[0256] For the variable magnification optical system of Example 18, basic lens data is shown in Table 52, specifications and variable surface spacings are shown in Table 53, aspherical coefficients are shown in Table 54, and various aberration diagrams are shown in FIG.

[0257]

[0258]

[0259]

[0260] [Example 19] The configuration and movement locus of the variable magnification optical system of Example 19 are shown in Figure 39. The variable magnification optical system of Example 19 comprises, in order from the object side to the image side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having negative refractive power, and a sixth lens group G6 having positive refractive power. The middle group GM comprises the third lens group G3, the fourth lens group G4, and the fifth lens group G5. The final lens group GE comprises the sixth lens group G6. When varying 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. When focusing, the fourth lens group G4 and the fifth lens group G5 move while changing the spacing between them. The object-side focusing group is made up of the fourth lens group G4, and the image-side focusing group is made up of the fifth lens group G5. When focusing from an object at infinity to a closest object, the object-side focusing group and the image-side focusing group move toward the image side.

[0261] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and seven lenses, L31 to L37, in order from the object side to the image side. The fourth lens group G4 consists of two lenses, L41 and L42, in order from the object side to the image side. The fifth lens group G5 consists of one lens, L51. The sixth lens group G6 consists of one lens, L61.

[0262] For the variable magnification optical system of Example 19, basic lens data is shown in Table 55, specifications and variable surface spacing are shown in Table 56, aspherical coefficients are shown in Table 57, and various aberration diagrams are shown in FIG.

[0263]

[0264]

[0265]

[0266] [Example 20] The configuration and movement locus of the variable magnification optical system of Example 20 are shown in Figure 41. The variable magnification optical system of Example 20 consists, in order from the object side to the image side, of a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, a sixth lens group G6 having negative refractive power, a seventh lens group G7 having positive refractive power, and an eighth lens group G8 having negative refractive power. The middle lens group GM consists of the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7. The final lens group GE consists of the eighth lens group G8. When varying 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. When focusing, the fifth lens group G5 and the sixth lens group G6 move while changing the spacing between them. The object-side focusing group consists of the fifth lens group G5, and the image-side focusing group consists of the sixth lens group G6. When focusing from an object at infinity to the closest object, the object-side focusing group and the image-side focusing group move toward the image side.

[0267] The first lens group G1 consists of three lenses, L11 to L13, in order from the object side to the image side. The second lens group G2 consists of four lenses, L21 to L24, in order from the object side to the image side. The third lens group G3 consists of an aperture stop St and three lenses, L31 to L33, in order from the object side to the image side. The fourth lens group G4 consists of four lenses, L41 to L44, in order from the object side to the image side. The fifth lens group G5 consists of two lenses, L51 and L52, in order from the object side to the image side. The sixth lens group G6 consists of one lens, L61. The seventh lens group G7 consists of one lens, L71. The eighth lens group G8 consists of one lens, L81.

[0268] For the variable magnification optical system of Example 20, basic lens data is shown in Table 58, specifications and variable surface spacings are shown in Table 59, aspherical coefficients are shown in Table 60, and various aberration diagrams are shown in FIG.

[0269]

[0270]

[0271]

[0272] Tables 61 to 65 show the corresponding values ​​of conditional expressions (1) to (40) for the variable magnification optical systems of Examples 1 to 20. A "-" is entered in any column where there is no corresponding lens. The corresponding values ​​of the Examples shown in Tables 61 to 65 may be used as the upper or lower limits of the conditional expressions to set preferred ranges for the conditional expressions.

[0273]

[0274]

[0275]

[0276]

[0277]

[0278] The variable magnification optical systems of Examples 1 to 20 are compact, yet achieve a small F-number of 3.3 or less over the entire range of magnification. In particular, some Examples have an F-number of 3 or less over the entire range of magnification. Furthermore, the variable magnification optical systems of Examples 1 to 20 maintain high optical performance with various aberrations well corrected over the entire range of magnification.

[0279] Next, an imaging device according to an embodiment of the present disclosure will be described. Figures 43 and 44 show external views of a camera 30, which is an imaging device according to an embodiment of the present disclosure. Figure 43 shows a perspective view of the camera 30 as seen from the front, and Figure 44 shows a perspective view of the camera 30 as seen from the rear. 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.

[0280] The camera 30 includes a camera body 31, and 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.

[0281] A photographic opening through which light from a subject to be photographed enters is provided in the center of the front face of the camera body 31, and a mount 37 is provided at a position corresponding to the photographic opening, and an interchangeable lens 20 is attached to the camera body 31 via the mount 37.

[0282] The camera body 31 contains an imaging element such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) that outputs an imaging signal corresponding to the subject image formed by the interchangeable lens 20, a signal processing circuit that processes the imaging signal output from the imaging element to generate an image, and a recording medium for recording the generated image. The camera 30 is capable of taking still images or videos by pressing the shutter button 32, and the image data obtained by this shooting is recorded on the recording medium.

[0283] 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.

[0284] 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.

[0285] The following supplementary items are further disclosed regarding the above embodiments and examples. [Additional Item 1] The zoom lens comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate group, and a final lens group having refractive power, the intermediate group consisting of one or more and five or less lens groups, and during zooming, the interval between the first lens group and the second lens group changes, the interval between the second lens group and the intermediate group changes, and the interval between the intermediate group and the final lens group changes, and when the intermediate group consists of a plurality of lens groups, the intervals between all of the adjacent lens groups in the intermediate group change during zooming, an aperture stop is disposed between the lens surface of the second lens group closest to the image side and the lens surface of the final lens group closest to the object side, and the first lens group includes, in succession from the most object side to the image side, a first lens which is a negative lens and a second lens which is a positive lens, and the distance on the optical axis from the object side surface of the first lens to the aperture stop when focused on an object at infinity at the wide-angle end is denoted by DDL1STw, When the sum of the distance on the optical axis from the object-side surface of the first lens to the lens surface closest to the image in the final lens group when focused on an object at infinity at the wide-angle end and the back focus of the entire system in air-equivalent distance is TLw, the maximum F-number when focused on an object at infinity at the telephoto end is Fnot, the focal length of the entire system when focused on an object at infinity at the telephoto end is ft, the focal length of the entire system when focused on an object at infinity at the wide-angle end is fw, the back focus of the entire system at the wide-angle end in air-equivalent distance is Bfw, and the maximum half angle of view when focused on an object at infinity at the telephoto end is ωt, the following relationships are satisfied: 0<DDL1STw / TLw<0.5 (1) 0.5<Fnot / (ft / fw)<1.3 (2) 0.15<Bfw / (ft×tanωt)<2 (3) A variable magnification optical system that satisfies conditional expressions (1), (2), and (3) expressed by the following formula: [Addendum 2] A variable magnification optical system according to Addendum 1 that satisfies conditional expression (4) expressed by the following formula: 1<fw / (ft×tan ωt)<1.4 (4).[Addendum 3] A variable magnification optical system according to Addendum 1 or 2, which satisfies conditional expression (5) expressed as follows: -6.6<f1 / fL1STw<-1.5 (5) where f1 is the focal length of the first lens group, and fL1STw is a composite focal length of the optical system from the first lens to the aperture stop in a state where the optical system is focused on an object at infinity at the wide-angle end. [Addendum 4] A variable magnification optical system according to any one of Addendums 1 to 3, which satisfies conditional expression (6) expressed as follows: -0.9<f1 / fL1<-0.05 (6) where f1 is the focal length of the first lens group, and fL1 is the focal length of the first lens. [Additional Item 5] A variable magnification optical system according to any one of Additional Items 1 to 4, which satisfies conditional expression (7) expressed as follows: −1.4<fw / fL1STw<−0.3 (7), where fL1STw is a composite focal length of the optical system from the first lens to the aperture stop when focused on an object at infinity at the wide-angle end. [Additional Item 6] A variable magnification optical system according to Additional Item 1, which satisfies conditional expressions (4), (5), (6), and (7) expressed as follows: 1<fw / (ft×tanωt)<1.4 (4) −6.6<f1 / fL1STw<−1.5 (5) −0.9<f1 / fL1<−0.05 (6) −1.4<fw / fL1STw<−0.3 (7) [Additional Item 7] A variable magnification optical system according to any one of Additional Items 1 to 6, which satisfies conditional expression (8) expressed as 2<TLw / (ft×tanωt)<9 (8) [Addendum 8] A variable magnification optical system according to any one of Addendums 1 to 7, which satisfies conditional expression (9) expressed as follows: 1.1<β2t / β2w<3 (9) where β2t is the lateral magnification of the second lens group when focused on an object at infinity at the telephoto end, and β2w is the lateral magnification of the second lens group when focused on an object at infinity at the wide-angle end.[Additional Item 9] A variable magnification optical system according to any one of Additional Items 1 to 8, which satisfies conditional expression (10) expressed by 0.1<|DDG12w-DDG12t| / TLt<0.3 (10), where DDG12w is the distance on the optical axis between the first lens group and the second lens group when focused on an object at infinity at the wide-angle end, DDG12t is the distance on the optical axis between the first lens group and the second lens group when focused on an object at infinity at the telephoto end, and TLt is the sum of the distance on the optical axis from the object-side surface of the first lens 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 of the entire system in air-equivalent distance. [Addendum 10] A variable magnification optical system according to any one of Addendums 1 to 9, which satisfies conditional expression (11) expressed by: 0.2<DDL1STw / f1<0.8 (11) where f1 is the focal length of the first lens group. [Addendum 11] A variable magnification optical system according to any one of Addendums 1 to 10, which satisfies conditional expression (12) expressed by: 3<DDL1STw / {(fw×tanωw)×log(ft / fw)} / <9 (12) where ωw is the maximum half angle of view in a state focused on an object at infinity at the wide-angle end. [Addendum 12] A variable magnification optical system according to any one of Addendums 1 to 11, which satisfies conditional expression (13) expressed by: 3<TLw / fw<8 (13). [Additional Item 13] A variable magnification optical system according to any one of Additional Items 1 to 12, which satisfies conditional expression (14) expressed as follows: 1.5<TLt / ft<3 (14) where TLt is the sum of the distance on the optical axis from the object-side surface of the first lens 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 of the entire system in air-equivalent distance. [Additional Item 14] A variable magnification optical system according to any one of Additional Items 1 to 13, which satisfies conditional expression (15) expressed as follows: 5<TLt / (ft×tanωt)<11 (15) where TLt is the sum of the distance on the optical axis from the object-side surface of the first lens 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 of the entire system in air-equivalent distance.[Addendum 15] A variable magnification optical system according to any one of Addendums 1 to 14, satisfying conditional expression (16) expressed by: 3<f1 / fw<7 (16) where the focal length of the first lens group is f1. [Addendum 16] A variable magnification optical system according to any one of Addendums 1 to 15, satisfying conditional expression (17) expressed by: 3<f1 / (-f2)<9 (17) where the focal length of the first lens group is f1 and the focal length of the second lens group is f2. [Addendum 17] A variable magnification optical system according to any one of Addendums 1 to 16, satisfying conditional expression (18) expressed by: 2<f1 / (ft / Fnot)<7 (18) where the focal length of the first lens group is f1. [Addendum 18] A variable magnification optical system according to any one of Addendums 1 to 16, satisfying conditional expression (18) expressed by: 1.8<f1 / (fw×ft). １／２ <4.2 (19) [Additional Item 19] A variable magnification optical system according to any one of Additional Items 1 to 18, which satisfies conditional expression (20) expressed by: 2<Denw / {(fw×tanωw)×log(ft / fw)}<4.5 (20) [Additional Item 20] A variable magnification optical system according to any one of Additional Items 1 to 18, which satisfies conditional expression (20) expressed by: 2<Denw / {(fw×tanωw)×log(ft / fw)}<4.5 (20) [Additional Item 20] A variable magnification optical system according to any one of Additional Items 1 to 18, which satisfies conditional expression (20) expressed by: 0.5<Denw / (fw×ft) １／２<1 (21) [Additional Item 21] The variable magnification optical system according to any one of Additional Items 1 to 20, satisfying conditional expression (22) expressed by 0.04<d1 / (Denw×tanωw)<0.09 (22), where d1 is the central thickness of the first lens, Denw is the distance on the optical axis from the object-side surface of the first lens to the paraxial entrance pupil position 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. [Addendum 22] The variable magnification optical system according to any one of Addendums 1 to 21, wherein Dexw is the distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity at the wide-angle end, the sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with respect to the image plane, and when an optical element having no refractive power is disposed between the image plane and the paraxial exit pupil position, and Dexw is calculated using an air-equivalent distance for the optical element, -0.65<fw / Dexw<-0.2 (23) [Addendum 23] The variable magnification optical system according to any one of Addendums 1 to 22, wherein EDf is the effective diameter of the object-side surface of the first lens, and EDr is the effective diameter of the lens surface of the final lens group closest to the image side, [Addendum 24] The variable magnification optical system according to any one of Addendums 1 to 23, satisfying conditional expression (25) expressed as follows: 0.35<EDf / TLw<0.65 (25) where EDf is the effective diameter of the object-side surface of the first lens. [Addendum 25] The variable magnification optical system according to any one of Addendums 1 to 24, satisfying conditional expression (26) expressed as follows: 2.2<ft / fw<4.8 (26) [Supplementary Item 26] A variable magnification optical system according to any one of Supplementary Items 1 to 25, satisfying the following conditional expressions (27), (28), and (29): 1.8<NdL1<2.01 (27) 15<νdL1<45 (28) 2<NdL1+0.01×νdL1<2.5 (29) where NdL1 is the refractive index of the first lens with respect to the d-line and νdL1 is the Abbe number of the first lens based on the d-line.[Supplementary Item 27] ​​A variable magnification optical system according to any one of Supplementary Items 1 to 26, satisfying conditional expressions (30), (31), and (32) expressed by: 1.43<NdL2<1.81 (30) 45<νdL2<96 (31) 2<NdL2+0.01×νdL2<2.5 (32) where NdL2 is the refractive index of the second lens with respect to the d line and νdL2 is the Abbe number of the second lens based on the d line. [Supplementary Item 28] A variable magnification optical system according to any one of Supplementary Items 1 to 27, which includes at least one focusing group that moves during variable magnification and during focusing, and satisfies conditional expression (33) expressed by the following equation: 0.3<|ffoc / fMt|<4 (33) where ffoc is the focal length of the focusing group that has the smallest absolute value of focal length among the focusing groups included in the variable magnification optical system, and fMt is the focal length of the intermediate group when focused on an object at infinity at the telephoto end. [Additional Item 29] The variable magnification optical system includes at least one focusing group that moves during zooming and focusing, and among the focusing groups included in the variable magnification optical system, the focusing group with the largest absolute value of focal length is at the telephoto end where the lateral magnification is in focus on an object at infinity, and βfRt is the combined lateral magnification of all lenses on the image side of the focusing group with the largest absolute value of focal length when they are at the telephoto end where they are in focus on an object at infinity, such that 1<|(1-βft. ２ ) × βfRt ２|<8 (34) is satisfied. [Additional Item 30] A variable magnification optical system according to any one of Additional Items 1 to 29, wherein one of the lens groups included in the intermediate group is a focusing group that moves during magnification variation and focusing. [Additional Item 31] A variable magnification optical system according to Additional Item 30, wherein the focusing group is made up of one positive lens and two negative lenses. [Addendum 32] A variable magnification optical system according to Addendum 31, wherein the negative lens closest to the image side in the focusing group is an aspherical lens, and wherein the following conditional expression (35) is satisfied: 0.1<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<3 (35) where Rcnf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcnr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Rynf is the radius of curvature at the position of maximum effective diameter of the object-side surface of the aspherical lens, and Rynr is the radius of curvature at the position of maximum effective diameter of the image-side surface of the aspherical lens. [Addendum 33] A variable magnification optical system according to Addendum 30, wherein the focusing group is made up of one negative lens and two positive lenses. [Addendum 34] A variable magnification optical system according to Addendum 33, wherein the positive lens closest to the image side in the focusing group is an aspherical lens, and wherein, where Rcpf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcpr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Rypf is the radius of curvature of the object-side surface of the aspherical lens at the position of maximum effective diameter, and Rypr is the radius of curvature of the image-side surface of the aspherical lens at the position of maximum effective diameter, the variable magnification optical system satisfies conditional expression (36) expressed as follows: -120<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-3 (36) [Addendum 35] The variable magnification optical system according to Addendum 30, wherein the focusing group consists of one positive lens and one negative lens. [Addendum 36] The variable magnification optical system according to Addendum 30, wherein the focusing group consists of one negative lens.[Addendum 37] A variable magnification optical system according to Addendum 36, wherein the negative lens in the focusing group is an aspherical lens, and wherein, where Rcsnf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcsnr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Rysnf is the radius of curvature of the object-side surface of the aspherical lens at the position of maximum effective diameter, and Rysnr is the radius of curvature of the image-side surface of the aspherical lens at the position of maximum effective diameter, the following condition (37) is satisfied: 0.1<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<3.5 (37) [Addendum 38] A variable magnification optical system according to any one of Addendums 1 to 29, wherein two of the lens groups included in the intermediate group are focusing groups that move while changing the distance between them during magnification variation and focusing. [Supplementary Item 39] When, of the two lens groups, the lens group arranged on the object side is an object-side focusing group, and the lens group arranged on the image side is an image-side focusing group, the object-side focusing group is made up of one negative lens and one positive lens, and the image-side focusing group is made up of one positive lens. This is a variable magnification optical system as described in Supplementary Item 38. [Addendum 40] A variable magnification optical system according to Addendum 39, wherein the positive lens of the image-side focusing group is an aspherical lens, and satisfies conditional expression (38) expressed by: 1<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<100 (38), where Rcipf is the paraxial radius of curvature of the object-side surface of the aspherical lens, Rcipr is the paraxial radius of curvature of the image-side surface of the aspherical lens, Ryipf is the radius of curvature of the object-side surface of the aspherical lens at the position of maximum effective diameter, and Ryipr is the radius of curvature of the image-side surface of the aspherical lens at the position of maximum effective diameter. [Addendum 41] When, of the two lens groups, the lens group arranged on the object side is an object-side focusing group and the lens group arranged on the image side is an image-side focusing group, the object-side focusing group is made up of one positive lens and one negative lens, and the image-side focusing group is made up of one negative lens. This is a variable magnification optical system as described in Addendum 38.[Addendum 42] A variable magnification optical system according to Addendum 41, wherein the negative lens of the image-side focusing group is an aspherical lens, and wherein the paraxial radius of curvature of the object-side surface of the aspherical lens is Rcinf, the paraxial radius of curvature of the image-side surface of the aspherical lens is Rcinr, the radius of curvature of the object-side surface of the aspherical lens at the position of maximum effective diameter is Ryinf, and the radius of curvature of the image-side surface of the aspherical lens at the position of maximum effective diameter is Ryinr. [Addendum 43] A variable magnification optical system according to any one of Addendums 1 to 42, including a plurality of lens groups that move along the same movement locus when varying magnification from the wide-angle end to the telephoto end. [Addendum 44] The variable magnification optical system according to any one of Addendums 1 to 43, wherein the intermediate group includes the aperture stop closest to the object side. [Addendum 45] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists of, in order from the object side to the image side, a lens group having positive refractive power and a lens group having negative refractive power, and the final lens group has positive refractive power. [Addendum 46] The variable magnification optical system according to Addendum 45, wherein the final lens group is fixed with respect to the image plane during magnification variation. [Addendum 47] The variable magnification optical system according to Addendum 46, wherein the final lens group is made up of one positive aspherical lens, and satisfies conditional expression (40) expressed by the following: 0.1<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<5 (40) where RcEpf is the paraxial radius of curvature of the object-side surface of the aspherical lens, RcEpr is the paraxial radius of curvature of the image-side surface of the aspherical lens, RyEpf is the radius of curvature of the object-side surface of the aspherical lens at the position of maximum effective diameter, and RyEpr is the radius of curvature of the image-side surface of the aspherical lens at the position of maximum effective diameter. [Addendum 48] The variable magnification optical system according to Addendum 45, wherein the final lens group moves during magnification variation. [Addendum 49] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group is composed of, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power, and the final lens group has positive refractive power.[Addendum 50] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists, in order from the object side to the image side, of a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group has negative refractive power. [Addendum 51] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists, in order from the object side to the image side, of a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group has positive refractive power. [Addendum 52] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists, in order from the object side to the image side, of a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, and the final lens group has negative refractive power. [Addendum 53] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists, in order from the object side to the image side, of a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group has negative refractive power. [Addendum 54] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists, in order from the object side to the image side, of a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power, and the final lens group has positive refractive power. [Addendum 55] The variable magnification optical system according to any one of Addendums 1 to 44, wherein the intermediate group consists, in order from the object side to the image side, of a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power, and the final lens group has negative refractive power. [Addendum 56] The variable magnification optical system according to any one of Addendums 49 to 55, wherein the final lens group moves during magnification variation. [Supplementary Item 57] An imaging device including the variable magnification optical system according to any one of Supplementary Items 1 to 56.

[0286] 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. The optical system comprises, in order from the object side to the image side, a first lens group having positive refractive power, a second lens group having negative refractive power, an intermediate group, and a final lens group having refractive power, the intermediate group is composed of one or more and five or less lens groups, During magnification change, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the intermediate group changes, and the distance between the intermediate group and the final lens group changes, When the intermediate group is made up of a plurality of lens groups, the intervals between all of the adjacent lens groups in the intermediate group change during magnification. an aperture stop is disposed between a lens surface of the second lens group closest to the image side and a lens surface of the final lens group closest to the object side; the first lens group includes, in succession from the most object side to the image side, a first lens which is a negative lens and a second lens which is a positive lens; The distance on the optical axis from the object side surface of the first lens to the aperture stop when focused on an object at infinity at the wide-angle end is DDL1STw, TLw is the sum of the distance on the optical axis from the object side surface of the first lens to the lens surface of the final lens group closest to the image side when focused on an object at infinity at the wide-angle end, and the back focus of the entire system in air equivalent distance; The maximum F-number when the lens is focused on an object at infinity at the telephoto end is Fnot. The focal length of the entire system when focused on an object at infinity at the telephoto end is ft. The focal length of the entire system when focused on an object at infinity at the wide-angle end is fw. The back focus of the entire system at the wide-angle end in terms of air is Bfw. If the maximum half angle of view when focused on an object at infinity at the telephoto end is ωt, 0<DDL1STw / TLw<0.5 (1) 0.5<Fnot / (ft / fw)<1.3 (2) 0.15<Bfw / (ft×tanωt)<2 (3) A variable magnification optical system that satisfies conditional expressions (1), (2), and (3) expressed by the following formula:

2. 1<fw / (ft×tanωt)<1.4 (4) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (4) expressed by:

3. The focal length of the first lens group is f1, When the composite focal length of the optical system from the first lens to the aperture stop in a state in which the focus is on an object at infinity at the wide-angle end is fL1STw, -6.6<f1 / fL1STw<-1.5 (5) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (5) expressed by:

4. The focal length of the first lens group is f1, When the focal length of the first lens is fL1, -0.9<f1 / fL1<-0.05 (6) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (6) expressed as follows:

5. When the composite focal length of the optical system from the first lens to the aperture stop in a state in which the focus is on an object at infinity at the wide-angle end is fL1STw, -1.4<fw / fL1STw<-0.3 (7) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (7) expressed as follows:

6. fL1STw is a composite focal length of the optical system from the first lens to the aperture stop when the optical system is focused on an object at infinity at the wide-angle end; The focal length of the first lens group is f1, When the focal length of the first lens is fL1, 1<fw / (ft×tanωt)<1.4 (4) -6.6<f1 / fL1STw<-1.5 (5) -0.9<f1 / fL1<-0.05 (6) -1.4<fw / fL1STw<-0.3 (7) 2. The variable magnification optical system according to claim 1, which satisfies the conditions (4), (5), (6), and (7) represented by the following formula:

7. 2<TLw / (ft×tanωt)<9 (8) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (8) expressed as follows:

8. The lateral magnification of the second lens group when focused on an object at infinity at the telephoto end is β2t, If the lateral magnification of the second lens group when focused on an object at infinity at the wide-angle end is β2w, 1.1<β2t / β2w<3 (9) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (9) expressed as follows:

9. The distance on the optical axis between the first lens group and the second lens group when focused on an object at infinity at the wide-angle end is DDG12w, The distance on the optical axis between the first lens group and the second lens group when focused on an object at infinity at the telephoto end is DDG12t, When the sum of the distance on the optical axis from the object side surface of the first lens to the lens surface of the final lens group closest to the image side in a state in which the lens is focused on an object at infinity at the telephoto end and the back focus of the entire system in terms of an air equivalent distance is denoted by TLt, 0.1<|DDG12w-DDG12t| / TLt<0.3 (10) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (10) expressed as follows:

10. If the focal length of the first lens group is f1, 0.2<DDL1STw / f1<0.8 (11) 2. The variable magnification optical system according to claim 1, which satisfies the conditional expression (11) expressed as follows:

11. If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, 3<DDL1STw / {(fw×tanωw)×log(ft / fw)}<9 (12) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (12) expressed as follows:

12. 3<TLw / fw<8 (13) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (13) expressed as follows:

13. When the sum of the distance on the optical axis from the object side surface of the first lens to the lens surface of the final lens group closest to the image side in a state in which the lens is focused on an object at infinity at the telephoto end and the back focus of the entire system in terms of an air equivalent distance is denoted by TLt, 1.5<TLt / ft<3 (14) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (14) expressed as follows:

14. When the sum of the distance on the optical axis from the object side surface of the first lens to the lens surface of the final lens group closest to the image side in a state in which the lens is focused on an object at infinity at the telephoto end and the back focus of the entire system in terms of an air equivalent distance is denoted by TLt, 5<TLt / (ft×tanωt)<11 (15) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (15) expressed as follows:

15. If the focal length of the first lens group is f1, 3<f1 / fw<7 (16) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (16) expressed as follows:

16. The focal length of the first lens group is f1, If the focal length of the second lens group is f2, 3<f1 / (-f2)<9 (17) 2. The variable magnification optical system according to claim 1, which satisfies the conditional expression (17) expressed as follows:

17. If the focal length of the first lens group is f1, 2<f1 / (ft / Fnot)<7 (18) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (18) expressed as follows:

18. If the focal length of the first lens group is f1, 1.8<f1 / (fw×ft) １／２ <4.2 (19) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (19) expressed as follows:

19. Denw is the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end, If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, 2<Denw / {(fw×tanωw)×log(ft / fw)}<4.5 (20) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (20) expressed as follows:

20. When the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position in a state in which the object is focused on an object at infinity at the wide-angle end is Denw, FIFAREIGHT(bight×x) １／２ 11 (21) 2. The variable magnification optical system according to claim 1, which satisfies the conditional expression (21) expressed as follows:

21. The center thickness of the first lens is d1. Denw is the distance on the optical axis from the object side surface of the first lens to the paraxial entrance pupil position when focused on an object at infinity at the wide-angle end, If the maximum half angle of view when focused on an object at infinity at the wide-angle end is ωw, 0.04<d1 / (Denw×tanωw)<0.09 (22) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (22) expressed by:

22. The distance on the optical axis from the image plane to the paraxial exit pupil position when focused on an object at infinity at the wide-angle end is Dexw. The sign of Dexw is positive for the distance on the image side and negative for the distance on the object side with respect to the image surface. In the case where an optical element having no refractive power is disposed between the image surface and the paraxial exit pupil position, when calculating Dexw for the optical element using an air-equivalent distance, -0.65<fw / Dexw<-0.2 (23) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (23) expressed as follows:

23. The effective diameter of the object side surface of the first lens is EDf. If the effective diameter of the lens surface of the final lens group closest to the image side is E Dr, 1.5<EDf / EDr<3 (24) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (24) expressed as follows:

24. When the effective diameter of the object side surface of the first lens is EDf, 0.35<EDf / TLw<0.65 (25) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (25) expressed as follows:

25. 2.2<ft / fw<4.8 (26) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (26) expressed as follows:

26. The refractive index of the first lens with respect to the d-line is NdL1, When the Abbe number of the first lens based on the d-line is νdL1, 1.8<NdL1<2.01 (27) 15<νdL1<45 (28) 2<NdL1+0.01×νdL1<2.5 (29) 2. The variable magnification optical system according to claim 1, which satisfies conditional expressions (27), (28), and (29) expressed by the following formula:

27. The refractive index of the second lens with respect to the d-line is NdL2, When the Abbe number of the second lens based on the d-line is νdL2, 1.43<NdL2<1.81 (30) 45<νdL2<96 (31) 2<NdL2+0.01×νdL2<2.5 (32) 2. The variable magnification optical system according to claim 1, which satisfies the conditions (30), (31), and (32) expressed by the following formula:

28. at least one focusing group that moves during zooming and during focusing; Among the focusing groups included in the variable magnification optical system, the focal length of the focusing group having the smallest absolute value of the focal length is designated as ffoc, When the focal length of the intermediate lens group when focused on an object at infinity at the telephoto end is fMt, 0.3<|ffoc / fMt|<4 (33) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (33) expressed as follows:

29. at least one focusing group that moves during zooming and during focusing; Among the focusing groups included in the variable magnification optical system, the focusing group having the largest absolute value of the focal length is at the telephoto end of the focusing group when focused on an object at infinity, and βft is the lateral magnification. When the composite lateral magnification of all the lenses on the image side of the focusing group having the largest absolute value of the focal length is in a state where the lenses are focused on an object at infinity at the telephoto end, it is assumed that βfRt is 1<|(1-βft ２ )×βfRt ２ |<8 (34) 2. The variable magnification optical system according to claim 1, which satisfies conditional expression (34) expressed as follows:

30. 2. A variable magnification optical system according to claim 1, wherein one of the lens groups included in the intermediate group is a focusing group that moves during magnification variation and during focusing.

31. 31. The variable magnification optical system according to claim 30, wherein the focusing group comprises one positive lens and two negative lenses.

32. the negative lens closest to the image side of the focusing group is an aspheric lens; The paraxial radius of curvature of the object side surface of the aspheric lens is Rcnf, The paraxial radius of curvature of the image-side surface of the aspheric lens is Rcnr, Rynf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens, When the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rynr, 0.1<(1 / Rcnf-1 / Rcnr) / (1 / Rynf-1 / Rynr)<3 （３５） 32. The variable magnification optical system according to claim 31, which satisfies conditional expression (35) expressed by:

33. 31. The variable magnification optical system according to claim 30, wherein the focusing group comprises one negative lens and two positive lenses.

34. the positive lens closest to the image side of the focusing group is an aspheric lens; The paraxial radius of curvature of the object side surface of the aspheric lens is Rcpf, The paraxial radius of curvature of the image-side surface of the aspheric lens is Rcpr, Rypf is the radius of curvature of the object-side surface of the aspheric lens at the position of the maximum effective diameter, If the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rypr, -120<(1 / Rcpf-1 / Rcpr) / (1 / Rypf-1 / Rypr)<-3 (36) 34. The variable magnification optical system according to claim 33, which satisfies conditional expression (36) expressed by:

35. 31. The variable magnification optical system according to claim 30, wherein the focusing group comprises one positive lens and one negative lens.

36. 31. The variable magnification optical system according to claim 30, wherein the focusing group is made up of one negative lens.

37. the negative lens in the focusing group is an aspheric lens; The paraxial radius of curvature of the object side surface of the aspheric lens is Rcsnf, The paraxial radius of curvature of the image-side surface of the aspheric lens is Rcsnr, Rysnf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens, When the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rysnr, 0.1<(1 / Rcsnf-1 / Rcsnr) / (1 / Rysnf-1 / Rysnr)<3.5 (37) 37. The variable magnification optical system according to claim 36, which satisfies conditional expression (37) represented by:

38. 2. A variable magnification optical system according to claim 1, wherein two of the lens groups included in the intermediate group are focusing groups which move while changing the distance between them during magnification and focusing.

39. Of the two lens groups, if the lens group arranged on the object side is defined as an object-side focusing group and the lens group arranged on the image side is defined as an image-side focusing group, then: the object-side focusing group is composed of one negative lens and one positive lens, 39. The variable magnification optical system according to claim 38, wherein the image-side focusing group consists of one positive lens.

40. the positive lens of the image-side focusing group is an aspheric lens; The paraxial radius of curvature of the object side surface of the aspheric lens is Rcipf, The paraxial radius of curvature of the image-side surface of the aspheric lens is Rcipr, Rypf is the radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens, When the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Rypr, 1<(1 / Rcipf-1 / Rcipr) / (1 / Ryipf-1 / Ryipr)<100 (38) 40. The variable magnification optical system according to claim 39, which satisfies conditional expression (38) expressed by:

41. Of the two lens groups, the lens group located on the object side is referred to as the object-side focusing group, and the lens group located on the image side is referred to as the object-side focusing group. If the lens group arranged in this way is used as the image-side focusing group, then the object-side focusing group is composed of one positive lens and one negative lens, 39. The variable magnification optical system according to claim 38, wherein the image-side focusing group consists of one negative lens.

42. the negative lens of the image-side focusing group is an aspheric lens; The paraxial radius of curvature of the object side surface of the aspheric lens is Rc inf , The paraxial radius of curvature of the image-side surface of the aspheric lens is Rcinr, The radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is Ryinf, When the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is Ryinr, 0.1<(1 / Rcinf-1 / Rcinr) / (1 / Ryinf-1 / Ryinr)<3.5 (39) 42. The variable magnification optical system according to claim 41, which satisfies conditional expression (39) represented by:

43. 2. A variable magnification optical system according to claim 1, comprising a plurality of lens groups that move along the same movement locus when varying magnification from the wide-angle end to the telephoto end.

44. 2. The variable magnification optical system according to claim 1, wherein the intermediate group includes the aperture stop closest to the object side.

45. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power and a lens group having negative refractive power, 2. The variable magnification optical system according to claim 1, wherein the final lens group has positive refractive power.

46. 46. ​​The variable magnification optical system according to claim 45, wherein the final lens group is fixed with respect to an image plane during magnification variation.

47. the final lens group is composed of one positive aspherical lens, The paraxial radius of curvature of the object side surface of the aspheric lens is RcEpf, The paraxial radius of curvature of the image-side surface of the aspheric lens is RcEpr, The radius of curvature at the position of the maximum effective diameter of the object side surface of the aspheric lens is RyEpf, If the radius of curvature at the position of the maximum effective diameter of the image side surface of the aspheric lens is RyEpr, 0.1<|(1 / RcEpf-1 / RcEpr) / (1 / RyEpf-1 / RyEpr)|<5 (40) 47. The variable magnification optical system according to claim 46, which satisfies conditional expression (40) expressed by:

48. 46. ​​The variable magnification optical system according to claim 45, wherein the final lens group moves during magnification variation.

49. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having negative refractive power; 2. The variable magnification optical system according to claim 1, wherein the final lens group has positive refractive power.

50. 50. The variable magnification optical system according to claim 49, wherein the final lens group moves during magnification variation.

51. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power; The variable magnification optical system according to claim 1 , wherein the final lens group has negative refractive power.

52. 52. The variable magnification optical system according to claim 51, wherein the final lens group moves during magnification variation.

53. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power; 2. The variable magnification optical system according to claim 1, wherein the final lens group has positive refractive power.

54. 54. The variable magnification optical system according to claim 53, wherein the final lens group moves during magnification variation.

55. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having positive refractive power, and a lens group having positive refractive power, The variable magnification optical system according to claim 1 , wherein the final lens group has negative refractive power.

56. 56. The variable magnification optical system according to claim 55, wherein the final lens group moves during magnification variation.

57. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having positive refractive power; The variable magnification optical system according to claim 1 , wherein the final lens group has negative refractive power.

58. 58. The variable magnification optical system according to claim 57, wherein the final lens group moves during magnification variation.

59. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, and a lens group having negative refractive power; 2. The variable magnification optical system according to claim 1, wherein the final lens group has positive refractive power.

60. 60. The variable magnification optical system according to claim 59, wherein the final lens group moves during magnification variation.

61. the intermediate group comprises, in order from the object side to the image side, a lens group having positive refractive power, a lens group having positive refractive power, a lens group having negative refractive power, a lens group having negative refractive power, and a lens group having positive refractive power; The variable magnification optical system according to claim 1 , wherein the final lens group has negative refractive power.

62. 62. The variable magnification optical system according to claim 61, wherein the final lens group moves during magnification variation.

63. 63. An imaging device comprising the variable magnification optical system according to claim 1.