Variable magnification optical system, optical apparatus, and method for manufacturing variable magnification optical system

Abstract

In order from the object side, the variable magnification optical system comprises a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a subsequent lens group comprising a plurality of lens groups, the first lens group and the third lens group are fixed with respect to the image plane during magnification change, and the second lens group is fixed with respect to the image plane during magnification change. The variable magnification optical system satisfies the following conditional expression: 0.24 < (TL / f1) / (ft / fw) < 0.55, where TL is the distance from the lens surface closest to the object side to the image surface, f1 is the focal length of the first lens group, ft is the focal length of the variable magnification optical system in a far-focus end state, and fw is the focal length of the variable magnification optical system in a wide-angle end state.

Description

Technical Field

[0001] The present disclosure relates to a zoom optical system, an optical device, and a method for manufacturing a zoom optical system. Background Art

[0002] Conventionally, a zoom optical system used in an optical device such as a camera for photographs, a digital still camera, or a video camera has been proposed (for example, refer to Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-189401 Summary of the Invention

[0006] The zoom optical system of the present disclosure includes, in order from the object side, a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a subsequent lens group having a plurality of lens groups. During zooming, the first lens group and the third lens group are fixed with respect to the image plane, and the intervals between adjacent lens groups change. The zoom optical system satisfies the following conditional expression: 0.24 < (TL / f1) / (ft / fw) < 0.55 Herein,[[]] TL: The distance from the lens surface closest to the object side to the image plane,[[]] f1: The focal length of the first lens group,[[]] ft: The focal length of the zoom optical system in the telephoto end state,[[]] fw: The focal length of the zoom optical system in the wide-angle end state.[[]]

[0007] The method for manufacturing the zoom optical system of the present disclosure includes configuring a zoom optical system that includes, in order from the object side, a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a subsequent lens group having a plurality of lens groups such that, during zooming, the first lens group and the third lens group are fixed with respect to the image plane, and the intervals between adjacent lens groups change. The zoom optical system satisfies the following conditional expression: 0.24 < (TL / f1) / (ft / fw) < 0.55 Herein,[[]] TL: The distance from the lens surface closest to the object side to the image plane,[[]] f1: The focal length of the first lens group,[[]] ft: The focal length of the zoom optical system in the telephoto end state,[[]] fw: The focal length of the zoom optical system in the wide-angle end state.[[]] Brief Description of the Drawings

[0008] Figure 1 It is a cross-sectional view of the zoom optical system according to the first embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0009] Figure 2 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system according to the first embodiment, and (b) is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system according to the first embodiment.

[0010] Figure 3 It is a cross-sectional view of the zoom optical system according to the second embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0011] Figure 4 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system according to the second embodiment, and (b) is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system according to the second embodiment.

[0012] Figure 5 It is a cross-sectional view of the zoom optical system according to the third embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0013] Figure 6 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system according to the third embodiment, and (b) is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system according to the third embodiment.

[0014] Figure 7 It is a cross-sectional view of the zoom optical system according to the fourth embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0015] Figure 8 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system according to the fourth embodiment, and (b) is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system according to the fourth embodiment.

[0016] Figure 9 It is a cross-sectional view of the zoom optical system according to the fifth embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0017] Figure 10 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system according to the fifth embodiment, and (b) is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system according to the fifth embodiment.

[0018] Figure 11It is a cross-sectional view of the zoom optical system of the sixth embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0019] Figure 12 (a) of is aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system of the sixth embodiment, and (b) is aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system of the sixth embodiment.

[0020] Figure 13 It is a schematic diagram of a camera equipped with the zoom optical system of this embodiment.

[0021] Figure 14 It is a schematic flowchart showing the manufacturing method of the zoom optical system of this embodiment. Detailed Embodiments

[0022] Hereinafter, the zoom optical system, the optical device, and the manufacturing method of the zoom optical system according to the embodiments of the present application will be described.

[0023] The zoom optical system of this embodiment sequentially includes a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a subsequent lens group having a plurality of lens groups from the object side. During zooming, the first lens group and the third lens group are fixed relative to the image plane, and the intervals between adjacent lens groups change. The zoom optical system satisfies the following conditional expressions.

[0024] (1) 0.24 < (TL / f1) / (ft / fw) < 0.55 Wherein, TL: The distance from the lens surface closest to the object side to the image plane f1: The focal length of the first lens group ft: The focal length of the zoom optical system in the telephoto end state fw: The focal length of the zoom optical system in the wide-angle end state

[0025] The zoom optical system of this embodiment includes a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a subsequent lens group having a plurality of lens groups, thereby being able to suppress the variation of various aberrations led by spherical aberration during zooming.

[0026] Conditional expression (1) defines the ratio of the distance from the lens surface closest to the object side to the image plane to the focal length of the first lens group and the ratio of the focal length of the zoom optical system in the wide-angle end state to the focal length in the telephoto end state (zoom ratio). The zoom optical system of this embodiment can suppress the variation of various aberrations led by spherical aberration during zooming by satisfying conditional expression (1).

[0027] In the zoom optical system of the present embodiment, if the value of conditional expression (1) exceeds the upper limit value, the optical power of the first lens group becomes too strong with respect to the distance from the lens surface closest to the object side to the image surface and the zoom ratio, and it becomes difficult to suppress fluctuations in various aberrations such as spherical aberration during zooming.

[0028] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (1) to 0.55, the effects of the present embodiment can be made more reliable. Additionally, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (1) to 0.53, and further to 0.50.

[0029] In addition, in the zoom optical system of the present embodiment, if the value of conditional expression (1) is lower than the lower limit value, the optical power of the first lens group becomes too weak with respect to the distance from the lens surface closest to the object side to the image surface and the zoom ratio, and it becomes difficult to suppress fluctuations in various aberrations such as spherical aberration during zooming.

[0030] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (1) to 0.24, the effects of the present embodiment can be made more reliable. Additionally, in order to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (1) to 0.28, 0.30, 0.33, and further to 0.36.

[0031] In addition, in the zoom optical system of the present embodiment, preferably, the following conditional expression is satisfied.

[0032] (2) 3.00 < f1 / (-f2) < 5.80 Wherein, f2: The focal length of the second lens group

[0033] Conditional expression (2) defines the ratio of the focal length of the first lens group to the focal length of the second lens group. By satisfying conditional expression (2), the zoom optical system of the present embodiment can suppress fluctuations in various aberrations such as coma during zooming.

[0034] In the zoom optical system of the present embodiment, if the value of conditional expression (2) exceeds the upper limit value, the optical power of the second lens group becomes too strong, and it becomes difficult to suppress fluctuations in various aberrations such as coma during zooming.

[0035] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (2) to 5.80, the effects of the present embodiment can be made more reliable. Additionally, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (2) to 5.60, and further to 5.40.

[0036] In addition, in the zoom optical system of the present embodiment, if the value of conditional expression (2) is lower than the lower limit value, the optical power of the first lens group becomes too strong, and it is difficult to suppress the variation of various aberrations led by coma during zooming.

[0037] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (2) to 3.00, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (2) to 3.30, 3.50, 3.75, and further to 3.90.

[0038] In addition, in the zoom optical system of the present embodiment, it is preferable to satisfy the following conditional expression.

[0039] (3) 0.45 < f1 / f3 < 6.00 Wherein, f3: The focal length of the third lens group

[0040] Conditional expression (3) defines the ratio of the focal length of the first lens group to the focal length of the third lens group. The zoom optical system of the present embodiment can suppress the variation of various aberrations led by coma during zooming by satisfying conditional expression (3).

[0041] In the zoom optical system of the present embodiment, if the value of conditional expression (3) exceeds the upper limit value, the optical power of the third lens group becomes too strong, and it is difficult to suppress the variation of various aberrations led by coma during zooming.

[0042] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (3) to 6.00, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (3) to 5.50, 5.00, 4.80, 4.50, and further to 4.00.

[0043] In addition, in the zoom optical system of the present embodiment, if the value of conditional expression (3) is lower than the lower limit value, the optical power of the first lens group becomes too strong, and it is difficult to suppress the variation of various aberrations led by coma during zooming.

[0044] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (3) to 0.45, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (3) to 0.50, 0.55, and further to 0.60.

[0045] In addition, in the zoom optical system of the present embodiment, the subsequent lens group includes a focusing lens group having a negative optical power and moving during focusing. Preferably, the following conditional expressions are satisfied.

[0046] (4) 0.30 < f2 / fF < 1.00 Wherein, f2: Focal length of the second lens group fF: Focal length of the focusing lens group

[0047] In the zoom optical system of the present embodiment, by including a focusing lens group in the subsequent lens group, it is possible to suppress fluctuations in various aberrations, mainly spherical aberration during focusing.

[0048] Conditional expression (4) defines the ratio of the focal length of the second lens group to the focal length of the focusing lens group. By satisfying conditional expression (4), the zoom optical system of the present embodiment can suppress fluctuations in various aberrations, mainly coma aberration during zooming, while suppressing fluctuations in various aberrations, mainly spherical aberration during focusing.

[0049] In the zoom optical system of the present embodiment, if the value of conditional expression (4) exceeds the upper limit value, the optical power of the focusing lens group becomes too strong, and it is difficult to suppress fluctuations in various aberrations, mainly spherical aberration during focusing.

[0050] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (4) to 1.00, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (4) to 0.90, 0.80, 0.75, and further to 0.70.

[0051] In addition, in the zoom optical system of the present embodiment, if the value of conditional expression (4) is lower than the lower limit value, the optical power of the second lens group becomes too strong, and it is difficult to suppress fluctuations in various aberrations, mainly coma aberration during zooming.

[0052] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (4) to 0.30, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (4) to 0.33, and further to 0.35.

[0053] In addition, in the zoom optical system of the present embodiment, preferably, the final lens group disposed on the most image plane side in the subsequent lens group is fixed relative to the image plane during zooming.

[0054] In the zoom optical system of the present embodiment, by having such a structure, it is possible to simplify the mechanism for moving each lens group during zooming, and make the zoom optical system smaller and lighter.

[0055] In addition, in the zoom optical system of the present embodiment, preferably, the subsequent lens group includes a focusing lens group having a negative optical power and moving during focusing and a final lens group disposed closest to the image plane side, and the following conditional expression is satisfied.

[0056] (5) 2.00 < |fR| / (-fF) < 100.00 Wherein, fR: Focal length of the final lens group fF: Focal length of the focusing lens group

[0057] Conditional expression (5) defines the ratio of the focal length of the final lens group to the focal length of the focusing lens group. By satisfying conditional expression (5), the zoom optical system of the present embodiment can suppress fluctuations in various aberrations including coma during zooming while suppressing fluctuations in various aberrations including spherical aberration during focusing.

[0058] In the zoom optical system of the present embodiment, if the value of conditional expression (5) exceeds the upper limit value, the optical power of the focusing lens group becomes too strong, and it is difficult to suppress fluctuations in various aberrations including spherical aberration during focusing.

[0059] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (5) to 100.00, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (5) to 80.00, 65.00, 55.00, 40.00, 25.00, and further to 15.00.

[0060] In addition, in the zoom optical system of the present embodiment, if the value of conditional expression (5) is lower than the lower limit value, the optical power of the final lens group becomes too strong, and it is difficult to suppress fluctuations in various aberrations including coma during zooming.

[0061] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (5) to 2.00, the effects of the present embodiment can be made more reliable. In addition, in order to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (5) to 2.30, 2.50, and further to 2.70.

[0062] In addition, in the zoom optical system of the present embodiment, preferably, the following conditional expression is satisfied.

[0063] (6) 0.15 < BFw / fw < 0.95 Wherein, BFw: Back focal length of the zoom optical system during infinity focusing in the wide-angle end state

[0064] Conditional expression (6) defines the ratio of the back focal length of the zoom optical system at infinity focus in the wide-angle end state to the focal length of the zoom optical system in the wide-angle end state. By satisfying conditional expression (6), the zoom optical system of the present embodiment can correct various aberrations such as coma at infinity focus in the wide-angle end state well.

[0065] In the zoom optical system of the present embodiment, if the value of conditional expression (6) exceeds the upper limit value, in the wide-angle end state, the back focal length becomes larger relative to the focal length, and it is difficult to correct various aberrations such as coma at infinity focus in the wide-angle end state well.

[0066] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (6) to 0.95, the effect of the present embodiment can be made more reliable. Additionally, in order to make the effect of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (6) to 0.92, and further to 0.90.

[0067] Furthermore, in the zoom optical system of the present embodiment, if the value of conditional expression (6) is lower than the lower limit value, in the wide-angle end state, the back focal length becomes smaller relative to the focal length, and it is difficult to correct various aberrations such as coma at infinity focus in the wide-angle end state well.

[0068] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (6) to 0.15, the effect of the present embodiment can be made more reliable. Additionally, in order to make the effect of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (6) to 0.20, 0.30, 0.40, and further to 0.45.

[0069] Moreover, in the zoom optical system of the present embodiment, preferably, the following conditional expression is satisfied.

[0070] (7) 0.08 < BFt / ft < 0.24 Wherein, BFt: The back focal length of the zoom optical system at infinity focus in the telephoto end state

[0071] Conditional expression (7) defines the ratio of the back focal length of the zoom optical system at infinity focus in the telephoto end state to the focal length of the zoom optical system in the telephoto end state. By satisfying conditional expression (7), the zoom optical system of the present embodiment can correct various aberrations such as coma at infinity focus in the telephoto end state well.

[0072] In the zoom optical system of the present embodiment, if the value of conditional expression (7) exceeds the upper limit value, in the telephoto end state, the back focal length becomes larger relative to the focal length, and it is difficult to satisfactorily correct various aberrations such as coma when focusing at infinity in the telephoto end state.

[0073] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (7) to 0.24, the effects of the present embodiment can be made more reliable. Additionally, in order to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (7) to 0.22, and further to 0.20.

[0074] In addition, in the zoom optical system of the present embodiment, if the value of conditional expression (7) is lower than the lower limit value, in the telephoto end state, the back focal length becomes smaller relative to the focal length, and it is difficult to satisfactorily correct various aberrations such as coma when focusing at infinity in the telephoto end state.

[0075] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (7) to 0.08, the effects of the present embodiment can be made more reliable. Additionally, in order to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (7) to 0.09, and further to 0.10.

[0076] In addition, in the zoom optical system of the present embodiment, preferably, the plurality of lens groups included in the subsequent lens group include at least one lens group having a positive optical power and satisfy the following conditional expression.

[0077] (8) 0.70 < f1 / fRP < 3.40 Wherein, fRP: The focal length of the lens group having the strongest optical power among the lens groups having a positive optical power included in the subsequent lens group

[0078] In the zoom optical system of the present embodiment, by including at least one lens group having a positive optical power in the subsequent lens group, fluctuations in various aberrations such as coma during zooming can be suppressed.

[0079] Conditional expression (8) defines the ratio of the focal length of the first lens group to the focal length of the lens group having the strongest optical power among the lens groups having a positive optical power included in the subsequent lens group. In the zoom optical system of the present embodiment, by satisfying conditional expression (8), fluctuations in various aberrations such as coma during zooming can be suppressed.

[0080] In the zoom optical system of the present embodiment, if the value of conditional expression (8) exceeds the upper limit value, the optical power of the lens group having the strongest optical power among the lens groups having a positive optical power included in the subsequent lens group becomes too strong, and it is difficult to suppress fluctuations in various aberrations such as coma during zooming.

[0081] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (8) to 3.40, the effects of the present embodiment can be made more reliable. Additionally, to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (8) to 3.30, 3.20, 3.08, and further to 3.00.

[0082] In the zoom optical system of the present embodiment, if the value of conditional expression (8) is lower than the lower limit value, the optical power of the first lens group becomes too strong, and it becomes difficult to suppress the variation of various aberrations such as coma during zooming.

[0083] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (8) to 0.70, the effects of the present embodiment can be made more reliable. Additionally, to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (8) to 0.72, 0.80, 0.85, 0.90, and further to 0.95.

[0084] In the zoom optical system of the present embodiment, preferably, the following conditional expression is satisfied.

[0085] (9) 0.50 < Gw / Gt < 1.50 where Gw: The distance from the lens surface closest to the object side of the zoom optical system to the center of gravity position of the zoom optical system in the wide-angle end state Gt: The distance from the lens surface closest to the object side of the zoom optical system to the center of gravity position of the zoom optical system in the telephoto end state

[0086] Conditional expression (9) defines the ratio of the distance from the lens surface closest to the object side of the zoom optical system to the center of gravity position of the zoom optical system in the wide-angle end state to the distance from the lens surface closest to the object side of the zoom optical system to the center of gravity position of the zoom optical system in the telephoto end state. By satisfying conditional expression (9), the change in the center of gravity position during zooming of the zoom optical system of the present embodiment becomes smaller, and high operability can be obtained.

[0087] In the zoom optical system of the present embodiment, when conditional expression (9) is not satisfied, the change in the center of gravity position during zooming becomes larger, which impairs the operability.

[0088] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (9) to 1.50, the effects of the present embodiment can be made more reliable. Additionally, to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (9) to 1.40, 1.30, 1.20, 1.10, and further to 1.00.

[0089] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (9) to 0.50, the effects of the present embodiment can be made more reliable. Additionally, to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (9) to 0.60, 0.70, 0.80, and further to 0.90.

[0090] Furthermore, in the zoom optical system of the present embodiment, it is preferable to satisfy the following conditional expression.

[0091] (10) 30.00° < ωw Where, ωw: Half field of view angle of the zoom optical system in the wide-angle end state

[0092] Conditional expression (10) defines the half field of view angle of the zoom optical system in the wide-angle end state. By satisfying conditional expression (10), the zoom optical system of the present embodiment can image a larger range of subjects on the image plane.

[0093] In the zoom optical system of the present embodiment, by setting the lower limit value of conditional expression (10) to 30.00°, the effects of the present embodiment can be made more reliable. Additionally, to make the effects of the present embodiment more reliable, it is preferable to set the lower limit value of conditional expression (10) to 34.00°, and further to 36.00°.

[0094] Furthermore, in the zoom optical system of the present embodiment, it is preferable to satisfy the following conditional expression.

[0095] (11) ωt < 15.00° Where, ωt: Half field of view angle of the zoom optical system in the telephoto end state

[0096] Conditional expression (11) defines the half field of view angle of the zoom optical system in the telephoto end state. By satisfying conditional expression (11), the zoom optical system of the present embodiment can image a more distant subject larger on the image plane.

[0097] In the zoom optical system of the present embodiment, by setting the upper limit value of conditional expression (11) to 15.00°, the effects of the present embodiment can be made more reliable. Additionally, to make the effects of the present embodiment more reliable, it is preferable to set the upper limit value of conditional expression (11) to 13.00°, and further to 12.00°.

[0098] With the above structure, a zoom optical system that is small-sized and has good imaging performance can be achieved.

[0099] The optical device of the present embodiment has a zoom optical system with the above-described structure. Thus, an optical device with good optical performance can be achieved.

[0100] The manufacturing method of the zoom optical system of the present embodiment includes configuring a zoom optical system that sequentially includes, from the object side, a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a subsequent lens group having a plurality of lens groups, such that, during zooming, the first lens group and the third lens group are fixed relative to the image plane, the intervals between adjacent lens groups change, and the zoom optical system satisfies the following conditional expressions.

[0101] (1) 0.24 < (TL / f1) / (ft / fw) < 0.55 Wherein, TL: The distance from the lens surface closest to the object side to the image plane f1: The focal length of the first lens group ft: The focal length of the zoom optical system in the telephoto end state fw: The focal length of the zoom optical system in the wide-angle end state

[0102] By such a manufacturing method of the optical system, a zoom optical system with good optical performance can be manufactured.

[0103] (Numerical Example)

[0104] Hereinafter, embodiments of the present application will be described based on the drawings.

[0105] (First Embodiment)

[0106] Figure 1 It is a cross-sectional view of the zoom optical system of the first embodiment when focusing on an infinite object in the wide-angle end state.

[0107] The zoom optical system of the present embodiment sequentially includes, from the object side, a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, a third lens group G3 having a positive optical power, a fourth lens group G4 having a negative optical power, and a fifth lens group G5 having a positive optical power.

[0108] The first lens group G1 is composed of, from the object side, a cemented positive lens formed by joining a meniscus-shaped negative lens L11 with a convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with a convex surface facing the object side.

[0109] The second lens group G2 is composed of, from the object side, a meniscus-shaped negative lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a meniscus-shaped negative lens L24 with a concave surface facing the object side.

[0110] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a positive lens L31 with a biconvex shape, a positive lens L32 with a biconvex shape, a cemented positive lens formed by a meniscus-shaped negative lens L33 with a concave surface facing the object side, and a cemented positive lens formed by a meniscus-shaped negative lens L34 with a convex surface facing the object side and a positive lens L35 with a biconvex shape.

[0111] The fourth lens group G4 is a cemented negative lens formed by a meniscus-shaped positive lens L41 with a concave surface facing the object side and a biconcave negative lens L42.

[0112] The fifth lens group G5 is composed of, in order from the object side, a positive lens L51 with a biconvex shape, a cemented negative lens formed by a meniscus-shaped positive lens L52 with a concave surface facing the object side and a biconcave negative lens L53, a cemented positive lens formed by a meniscus-shaped negative lens L54 with a convex surface facing the object side and a positive lens L55 with a biconvex shape, and a meniscus-shaped negative lens L56 with a concave surface facing the object side.

[0113] On the image plane I, an imaging element (not shown) composed of a CCD or a CMOS, etc. is disposed.

[0114] The zoom optical system of this embodiment performs focusing by moving the fourth lens group G4 along the optical axis. When focusing from an infinite focus state to a close object, the fourth lens group G4 moves from the object side toward the image side.

[0115] In the zoom optical system of this embodiment, the fourth lens group G4 and the fifth lens group G5 are equivalent to subsequent lens groups, the fourth lens group G4 is equivalent to the focusing lens group, and the fifth lens group G5 is equivalent to the final lens group. In addition, the fifth lens group G5 is equivalent to the lens group with the strongest optical power among the lens groups with positive optical power included in the subsequent lens groups.

[0116] The values of the parameters of the zoom optical system of this embodiment are described in Table 1 below.

[0117] In [Overall Parameters], TL represents the distance from the lens surface closest to the object side to the image plane, fw represents the focal length of the entire system in the wide-angle end state, ft represents the focal length of the entire system in the telephoto end state, FNOw represents the F-number in the wide-angle end state, FNOt represents the F-number in the telephoto end state, ωw represents the half field of view angle (degrees) in the wide-angle end state, ωt represents the half field of view angle (degrees) in the telephoto end state, and Y represents the maximum image height.

[0118] In [Lens Parameters], m represents the order of the optical surface counted from the object side, r represents the radius of curvature, d represents the surface interval, nd represents the refractive index for the d-line (wavelength 587.6 nm), and νd represents the Abbe number for the d-line. A radius of curvature r = ∞ represents a plane. Additionally, in [Lens Parameters], an optical surface with an asterisk "*" attached indicates an aspherical surface.

[0119] In [Aspherical Data], m represents the optical surface corresponding to the aspherical data, K represents the conic constant, and A4 - A12 represent the aspherical coefficients.

[0120] When the height in the direction perpendicular to the optical axis is set as y, the distance along the optical axis (depression amount) from the tangent plane of each aspherical surface at the vertex of height y to each aspherical surface is set as S(y), the radius of curvature of the reference sphere (paraxial radius of curvature) is set as r, the conic constant is set as K, and the aspherical coefficient of the nth order is set as An, the aspherical surface is represented by the following formula (a). Additionally, in each embodiment, the aspherical coefficient A2 of the second order is 0. Also, "E-n" represents "×10 -n ".

[0121] (a) S(y) = (y 2 / r) / {1 + (1 - K × y 2 / r 2 ) 1 / 2}

[0122] + A4 × y 4 + A6 × y 6 + A8 × y 8 + A10 × y 10 + A12 × y 12

[0123] The units of the focal lengths fw and ft, radius of curvature r, and other lengths described in Table 1 are "mm". However, equivalent optical performance can be obtained even if the optical system is scaled up or down, so it is not limited to this.

[0124] The symbols in Table 1 described above are also used in the tables of other embodiments described later.

[0125] (Table 1)

[0126] [Overall Parameters]

[0127] [Lens Parameters]

[0128] [Aspherical data]

[0129] [Focal length data for each group]

[0130] [Variable interval data]

[0131] Figure 2 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system of the first embodiment. Figure 2 (b) of is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system of the first embodiment.

[0132] In each aberration diagram, FNO represents the F-number, and Y represents the image height. Specifically, in the spherical aberration diagram, the value of the F-number corresponding to the maximum aperture is shown, in the astigmatism diagram and the distortion diagram, the maximum value of the image height is shown, and in the coma diagram, the values of each image height are shown. D represents the d-line, and g represents the g-line (wavelength 435.8 nm). In the astigmatism diagram, the solid line represents the sagittal image plane, and the dashed line represents the meridional image plane. The same symbols as those in the aberration diagrams of this embodiment are also used in the aberration diagrams of other embodiments described later.

[0133] It can be seen from each aberration diagram that the zoom optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0134] (Second embodiment)

[0135] Figure 3 is a cross-sectional view of the zoom optical system of the second embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0136] The zoom optical system of this embodiment sequentially includes a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, a third lens group G3 having a positive optical power, a fourth lens group G4 having a negative optical power, and a fifth lens group G5 having a positive optical power from the object side.

[0137] The first lens group G1 is composed of a cemented positive lens formed by a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with its convex surface facing the object side in sequence from the object side.

[0138] The second lens group G2 is composed of a meniscus-shaped negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a meniscus-shaped negative lens L24 with its concave surface facing the object side in sequence from the object side.

[0139] The third lens group G3 is composed of, in order from the object side, an aperture stop S, a positive lens L31 with a biconvex shape, a positive lens L32 with a biconvex shape, a combined positive lens formed by a meniscus-shaped negative lens L33 with its concave surface facing the object side joined to the above, and a combined positive lens formed by a meniscus-shaped negative lens L34 with its convex surface facing the object side joined to a positive lens L35 with a biconvex shape.

[0140] The fourth lens group G4 is a combined negative lens formed by a meniscus-shaped positive lens L41 with its concave surface facing the object side joined to a negative lens L42 with a biconcave shape.

[0141] The fifth lens group G5 is composed of, in order from the object side, a combined negative lens formed by a positive lens L51 with a biconvex shape joined to a meniscus-shaped negative lens L52 with its concave surface facing the object side, a positive lens L53 with a biconvex shape, and a meniscus-shaped negative lens L54 with its concave surface facing the object side.

[0142] On the image plane I, an imaging element (not shown) composed of a CCD, a CMOS, or the like is disposed.

[0143] In the zoom optical system of this embodiment, focusing is performed by moving the fourth lens group G4 along the optical axis. When changing the focus from an infinite focus state to a close object focus state, the fourth lens group G4 moves from the object side toward the image side.

[0144] In the zoom optical system of this embodiment, the fourth lens group G4 and the fifth lens group G5 are equivalent to the subsequent lens groups, the fourth lens group G4 is equivalent to the focusing lens group, and the fifth lens group G5 is equivalent to the final lens group. In addition, the fifth lens group G5 is equivalent to the lens group with the strongest optical power among the lens groups with positive optical power included in the subsequent lens groups.

[0145] The values of the parameters of the zoom optical system of this embodiment are described in Table 2 below.

[0146] (Table 2)

[0147] [Overall parameters]

[0148] [Lens parameters]

[0149] [Aspherical data]

[0150] [Focal length data for each group]

[0151] [Variable interval data]

[0152] Figure 4 (a) is an aberration diagram at the time of focusing on an infinitely distant object in the wide-angle end state of the zoom optical system of the second embodiment, Figure 4 (b) is an aberration diagram at the time of focusing on an infinitely distant object in the telephoto end state of the zoom optical system of the second embodiment.

[0153] From the aberration diagrams, it can be seen that the zoom optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0154] (Third Embodiment)

[0155] Figure 5 is a cross-sectional view of the zoom optical system of the third embodiment at the time of focusing on an infinitely distant object in the wide-angle end state.

[0156] The zoom optical system of this embodiment sequentially includes a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, a third lens group G3 having a positive optical power, a fourth lens group G4 having a positive optical power, a fifth lens group G5 having a negative optical power, and a sixth lens group G6 having a positive optical power from the object side.

[0157] The first lens group G1 is composed of a cemented positive lens of a meniscus-shaped negative lens L11 with the convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with the convex surface facing the object side in sequence from the object side.

[0158] The second lens group G2 is composed of a meniscus-shaped negative lens L21 with the convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a meniscus-shaped negative lens L24 with the concave surface facing the object side in sequence from the object side.

[0159] The third lens group G3 is composed of an aperture stop S, a biconvex positive lens L31, and a meniscus-shaped negative lens L32 with the concave surface facing the object side in sequence from the object side.

[0160] The fourth lens group G4 is composed of a meniscus-shaped positive lens L41 with the convex surface facing the object side, a biconvex positive lens L42, a cemented positive lens of a meniscus-shaped negative lens L43 with the convex surface facing the object side and a biconvex positive lens L44, and a meniscus-shaped negative lens L45 with the convex surface facing the object side in sequence from the object side.

[0161] The fifth lens group G5 is a cemented negative lens of a meniscus-shaped negative lens L51 with the convex surface facing the object side and a meniscus-shaped positive lens L52 with the convex surface facing the object side.

[0162] The sixth lens group G6 is composed of a negative lens L61 with a meniscus shape having a concave surface facing the object side and a positive lens L62 with a biconvex shape in order from the object side.

[0163] On the image plane I, an imaging element (not shown) composed of a CCD, a CMOS, or the like is disposed.

[0164] In the zoom optical system of this embodiment, focusing is performed by moving the fifth lens group G5 along the optical axis. When focusing on a close object from a state of focusing on infinity, the fifth lens group G5 moves from the object side toward the image plane side.

[0165] In the zoom optical system of this embodiment, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to subsequent lens groups, the fifth lens group G5 corresponds to a focusing lens group, and the sixth lens group G6 corresponds to a final lens group. In addition, the fourth lens group G4 corresponds to the lens group having the strongest optical power among the lens groups having a positive optical power included in the subsequent lens groups.

[0166] The values of the parameters of the zoom optical system of this embodiment are described in Table 3 below.

[0167] (Table 3)

[0168] [Overall parameters]

[0169] [Lens parameters]

[0170] [Aspherical data]

[0171] [Focal length data of each group]

[0172] [Variable interval data]

[0173] Figure 6 (a) of is aberration diagrams at the time of focusing on an infinite object in the wide-angle end state of the zoom optical system of the third embodiment, Figure 6 (b) of is aberration diagrams at the time of focusing on an infinite object in the telephoto end state of the zoom optical system of the third embodiment.

[0174] From the aberration diagrams, it can be seen that the zoom optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0175] (Fourth Embodiment)

[0176] Figure 7 This is a cross-sectional view of the zoom optical system according to the fourth embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0177] The zoom optical system of this embodiment includes, in order from the object side, a first lens group G1 having a positive optical power, a second lens group G2 having a negative optical power, a third lens group G3 having a positive optical power, a fourth lens group G4 having a positive optical power, a fifth lens group G5 having a negative optical power, and a sixth lens group G6 having a negative optical power.

[0178] The first lens group G1 is composed of, in order from the object side, a cemented positive lens formed by a meniscus-shaped negative lens L11 with its convex surface facing the object side and a meniscus-shaped positive lens L12 with its convex surface facing the object side, and a meniscus-shaped positive lens L13 with its convex surface facing the object side.

[0179] The second lens group G2 is composed of, in order from the object side, a meniscus-shaped negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a meniscus-shaped negative lens L24 with its concave surface facing the object side.

[0180] The third lens group G3 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens formed by a biconvex positive lens L31 and a meniscus-shaped negative lens L32 with its concave surface facing the object side.

[0181] The fourth lens group G4 is composed of, in order from the object side, a meniscus-shaped positive lens L41, a cemented positive lens formed by a meniscus-shaped positive lens L42 with its convex surface facing the object side and a biconvex positive lens L43, and a meniscus-shaped negative lens L44 with its convex surface facing the object side.

[0182] The fifth lens group G5 is a cemented negative lens formed by a meniscus-shaped negative lens L51 with its convex surface facing the object side and a meniscus-shaped positive lens L52 with its convex surface facing the object side.

[0183] The sixth lens group G6 is composed of, in order from the object side, a meniscus-shaped positive lens L61 with its concave surface facing the object side, a meniscus-shaped negative lens L62 with its concave surface facing the object side, and a biconvex positive lens L63.

[0184] On the image plane I, an imaging element (not shown) composed of a CCD or CMOS, etc. is arranged.

[0185] The zoom optical system of this embodiment focuses by moving the fifth lens group G5 along the optical axis. When focusing from an infinite focus state to a close object, the fifth lens group G5 moves from the object side to the image side.

[0186] In the zoom optical system of this embodiment, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 correspond to the subsequent lens groups, the fifth lens group G5 corresponds to the focusing lens group, and the sixth lens group G6 corresponds to the final lens group. In addition, the fourth lens group G4 corresponds to the lens group with the strongest optical power among the lens groups with positive optical power included in the subsequent lens groups.

[0187] The values of the parameters of the zoom optical system of this embodiment are listed in Table 4 below.

[0188] (Table 4)

[0189] [Overall parameters]

[0190] [Lens parameters]

[0191] [Aspherical data]

[0192] [Focal length data of each group]

[0193] [Variable interval data]

[0194] Figure 8 (a) of is the aberration diagrams when focusing on an infinite object in the wide-angle end state of the zoom optical system of the fourth embodiment. Figure 8 (b) of is the aberration diagrams when focusing on an infinite object in the telephoto end state of the zoom optical system of the fourth embodiment.

[0195] It can be seen from the aberration diagrams that the zoom optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0196] (The fifth embodiment)

[0197] Figure 9 is a cross-sectional view of the zoom optical system of the fifth embodiment when focusing on an infinite object in the wide-angle end state.

[0198] The zoom optical system of this embodiment sequentially includes a first lens group G1 with a positive optical power, a second lens group G2 with a negative optical power, a third lens group G3 with a positive optical power, a fourth lens group G4 with a positive optical power, a fifth lens group G5 with a positive optical power, a sixth lens group G6 with a negative optical power, and a seventh lens group G7 with a positive optical power from the object side.

[0199] The first lens group G1 is composed of a cemented positive lens formed by a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with its convex surface facing the object side in sequence from the object side.

[0200] The second lens group G2 is composed of a meniscus-shaped negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a meniscus-shaped negative lens L24 with its concave surface facing the object side in sequence from the object side.

[0201] The third lens group G3 is composed of an aperture stop S, a biconvex positive lens L31, and a meniscus-shaped negative lens L32 with its concave surface facing the object side in sequence from the object side.

[0202] The fourth lens group G4 is composed of a meniscus-shaped positive lens L41 with its convex surface facing the object side, and a cemented positive lens formed by a biconvex positive lens L42 and a meniscus-shaped negative lens L43 with its concave surface facing the object side in sequence from the object side.

[0203] The fifth lens group G5 is composed of a cemented positive lens formed by a meniscus-shaped negative lens L51 with its convex surface facing the object side and a biconvex positive lens L52, and a meniscus-shaped positive lens L53 with its convex surface facing the object side.

[0204] The sixth lens group G6 is a cemented negative lens formed by a meniscus-shaped negative lens L61 with its convex surface facing the object side and a meniscus-shaped positive lens L62 with its convex surface facing the object side.

[0205] The seventh lens group G7 is composed of a meniscus-shaped negative lens L71 with its concave surface facing the object side and a meniscus-shaped positive lens L72 with its convex surface facing the object side in sequence from the object side.

[0206] On the image plane I, an imaging element (not shown) composed of a CCD, a CMOS, or the like is arranged.

[0207] The zoom optical system of this embodiment performs focusing by moving the sixth lens group G6 along the optical axis. When focusing from an infinite focus state to a close object, the sixth lens group G6 moves from the object side toward the image side.

[0208] In the zoom optical system of this embodiment, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 are equivalent to the subsequent lens groups, the sixth lens group G6 is equivalent to the focusing lens group, and the seventh lens group G7 is equivalent to the final lens group. In addition, the fourth lens group G4 is equivalent to the lens group with the strongest optical power among the lens groups with positive optical power included in the subsequent lens groups.

[0209] The values of the parameters of the zoom optical system of this embodiment are described in Table 5 below.

[0210] (Table 5)

[0211] [Overall parameters]

[0212] [Lens parameters]

[0213] [Aspherical data]

[0214] [Focal length data of each group]

[0215] [Variable interval data]

[0216] Figure 10 (a) of is the aberration diagrams when focusing on an infinitely distant object in the wide-angle end state of the zoom optical system of the fifth embodiment. Figure 10 (b) of is the aberration diagrams when focusing on an infinitely distant object in the telephoto end state of the zoom optical system of the fifth embodiment.

[0217] It can be seen from the aberration diagrams that the zoom optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0218] (The sixth embodiment)

[0219] Figure 11 is a cross-sectional view of the zoom optical system of the sixth embodiment when focusing on an infinitely distant object in the wide-angle end state.

[0220] The zoom optical system of this embodiment sequentially includes a first lens group G1 with a positive optical power, a second lens group G2 with a negative optical power, a third lens group G3 with a positive optical power, a fourth lens group G4 with a positive optical power, a fifth lens group G5 with a positive optical power, a sixth lens group G6 with a negative optical power, and a seventh lens group G7 with a positive optical power from the object side.

[0221] The first lens group G1 is composed of a cemented positive lens formed by a meniscus-shaped negative lens L11 with its convex surface facing the object side and a biconvex positive lens L12, and a meniscus-shaped positive lens L13 with its convex surface facing the object side in sequence from the object side.

[0222] The second lens group G2 is composed of a meniscus-shaped negative lens L21 with its convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a meniscus-shaped negative lens L24 with its concave surface facing the object side in sequence from the object side.

[0223] The third lens group G3 is composed of an aperture stop S, a biconvex positive lens L31, and a meniscus-shaped negative lens L32 with its concave surface facing the object side in sequence from the object side.

[0224] The fourth lens group G4 is composed of a meniscus-shaped positive lens L41 with its convex surface facing the object side, and a cemented positive lens formed by a biconvex positive lens L42 and a meniscus-shaped negative lens L43 with its concave surface facing the object side in sequence from the object side.

[0225] The fifth lens group G5 is composed of a cemented positive lens formed by a meniscus-shaped negative lens L51 with its convex surface facing the object side and a biconvex positive lens L52, and a meniscus-shaped positive lens L53 with its convex surface facing the object side.

[0226] The sixth lens group G6 is a cemented negative lens formed by a meniscus-shaped negative lens L61 with its convex surface facing the object side and a meniscus-shaped positive lens L62 with its convex surface facing the object side.

[0227] The seventh lens group G7 is composed of a meniscus-shaped negative lens L71 with its concave surface facing the object side and a meniscus-shaped positive lens L72 with its convex surface facing the object side in sequence from the object side.

[0228] On the image plane I, an imaging element (not shown) composed of a CCD or CMOS, etc. is arranged.

[0229] The zoom optical system of this embodiment performs focusing by moving the sixth lens group G6 along the optical axis. When focusing from an infinite focus state to a close-range object, the sixth lens group G6 moves from the object side toward the image side.

[0230] In the zoom optical system of this embodiment, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 are equivalent to the subsequent lens groups. The sixth lens group G6 is equivalent to the focusing lens group, and the seventh lens group G7 is equivalent to the final lens group. In addition, the fourth lens group G4 is equivalent to the lens group with the strongest optical power among the lens groups with positive optical power included in the subsequent lens groups.

[0231] The values of the parameters of the zoom optical system of this embodiment are described in Table 6 below.

[0232] (Table 6)

[0233] [Overall parameters]

[0234] [Lens parameters]

[0235] [Aspherical data]

[0236] [Focal length data of each group]

[0237] [Variable interval data]

[0238] Figure 12 (a) of is the aberration diagrams when focusing on an infinite object in the wide-angle end state of the zoom optical system of the sixth embodiment, Figure 12 (b) of is the aberration diagrams when focusing on an infinite object in the telephoto end state of the zoom optical system of the sixth embodiment.

[0239] It can be seen from the aberration diagrams that the zoom optical system of this embodiment appropriately corrects various aberrations and has high optical performance.

[0240] According to the above embodiments, a zoom optical system with good optical performance can be realized.

[0241] Hereinafter, the conditional corresponding values of each embodiment are shown.

[0242] TL is the distance from the lens surface closest to the object to the image plane, fw is the focal length of the zoom optical system in the wide-angle end state, and ft is the focal length of the zoom optical system in the telephoto end state. f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, and f3 is the focal length of the third lens group. fF is the focal length of the focusing lens group, fR is the focal length of the final lens group, and fRP is the focal length of the lens group with the strongest positive optical power among the lens groups with positive optical power included in the subsequent lens group. BFw is the back focal length of the zoom optical system during infinity focusing in the wide-angle end state, and BFt is the back focal length of the zoom optical system during infinity focusing in the telephoto end state. Gw is the distance from the lens surface closest to the object of the zoom optical system to the center of gravity position of the zoom optical system in the wide-angle end state, and Gt is the distance from the lens surface closest to the object of the zoom optical system to the center of gravity position of the zoom optical system in the telephoto end state. ωw is the half field angle of the zoom optical system in the wide-angle end state, and ωt is the half field angle of the zoom optical system in the telephoto end state.

[0243] [Conditional formula corresponding value]

[0244] The above embodiments represent a specific example of the present invention, and the present invention is not limited thereto. The following content can be appropriately adopted within the range that does not damage the optical performance of the zoom optical system of the embodiment of the present application.

[0245] In the zoom optical system of the present embodiment, the third lens group may not have an aperture stop. In addition, the position of the aperture stop in the zoom optical system of the present embodiment is not limited to the position of the aperture stop S in the zoom optical systems of the above embodiments. The aperture stop in the zoom optical system of the present embodiment can be disposed between lenses within the third lens group.

[0246] The zoom optical system of the present embodiment may also have an optical member such as a filter between the lens surface closest to the image plane and the image plane.

[0247] The zoom optical system of the present embodiment may also have an anti-shake lens group that corrects image blur caused by hand shake by moving in a direction having a component perpendicular to the optical axis. The anti-shake lens group may be a lens group or a partial lens group composed of one or more lens components included in the lens group.

[0248] In the zoom optical system of the present embodiment, the lens surface may be formed by a spherical surface or a flat surface, or may be formed by an aspherical surface. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment become easy, and deterioration of optical performance due to errors in processing and assembly adjustment can be prevented, so this is preferred. In addition, when the lens surface is a spherical surface or a flat surface, deterioration of the drawing performance during image plane shift is small, so this is preferred.

[0249] When the lens surface is an aspherical surface, the aspherical surface may be formed by grinding a glass or using a glass mold having an aspherical shape, or may be formed on the surface of a resin bonded to the glass surface. In addition, in the zoom optical system of the present embodiment, the lens surface may be a diffractive surface, and the lens may also be a refractive index distribution type lens (GRIN lens) or a plastic lens.

[0250] Next, based on Figure 13 a camera including the zoom optical system of the present embodiment will be described.

[0251] Figure 13 is a schematic diagram of a camera having the zoom optical system of the present embodiment.

[0252] The camera 1 is a so-called mirrorless camera with interchangeable lenses that includes the optical system of the above-described first embodiment as a photographic lens 2.

[0253] In the camera 1, light from an object (subject) (not shown) is condensed by the photographic lens 2 and reaches the imaging element 3. The imaging element 3 converts the light from the subject into image data. When the photographer presses a release button (not shown), the image data is stored in a memory (not shown). In this way, the photographer can use the camera 1 to photograph the subject.

[0254] Here, the zoom optical system of the above-described first embodiment mounted on the camera 1 as the photographic lens 2 is a zoom optical system having good optical performance. Therefore, the camera 1 can achieve good optical performance. In addition, even when a camera is configured to mount the zoom optical systems of the above-described second to sixth embodiments as the photographic lens 2, the same effect as that of the camera 1 can be obtained.

[0255] Finally, based on Figure 14 an outline of a manufacturing method of the zoom optical system of the present embodiment will be described.

[0256] Figure 14 is a flowchart showing an outline of the manufacturing method of the zoom optical system of the present embodiment. Figure 14 The manufacturing method of the zoom optical system of the present embodiment shown includes the following steps S11 - S13.

[0257] Step S11: Prepare the first lens group, the second lens group, the third lens group and subsequent lens groups.

[0258] Step S12: During zooming, keep the first lens group and the third lens group fixed relative to the image plane, and vary the intervals between adjacent lens groups.

[0259] Step S13: Make the zoom optical system satisfy the following conditional formula.

[0260] (1) 0.24 < (TL / f1) / (ft / fw) < 0.55

[0261] Where,

[0262] TL: The distance from the lens surface closest to the object side to the image plane

[0263] f1: The focal length of the first lens group

[0264] ft: The focal length of the zoom optical system in the telephoto end state

[0265] fw: The focal length of the zoom optical system in the wide-angle end state

[0266] According to the manufacturing method of the zoom optical system of the present embodiment, an optical system with good imaging performance can be manufactured.

[0267] It should be understood that those skilled in the art can make various changes, substitutions and modifications to it without departing from the spirit and scope of the present disclosure.

[0268] Reference Signs Description

[0269] S Aperture stop

[0270] I Image plane

[0271] 1 Camera

[0272] 2 Photographic lens

[0273] 3 Imaging element

Claims

1. A variable magnification optical system, wherein, from the object side, it successively includes a first lens group having a positive optical power, a second lens group having a negative optical power, a third lens group having a positive optical power, and a subsequent lens group having a plurality of lens groups, during variable magnification, the first lens group and the third lens group are fixed relative to the image plane, and the intervals between adjacent lens groups change, the variable magnification optical system satisfies the following conditional expression: 0.24 < (TL / f1) / (ft / fw) < 0.55 wherein, TL: the distance from the lens surface closest to the object side to the image plane, f1: the focal length of the first lens group, ft: the focal length of the variable magnification optical system in the telephoto end state, fw: the focal length of the variable magnification optical system in the wide-angle end state.

2. The variable magnification optical system according to claim 1, wherein, the variable magnification optical system satisfies the following conditional expression: 3.00 < f1 / (-f2) < 5.80 wherein, f2: the focal length of the second lens group.

3. The variable magnification optical system according to claim 1 or 2, wherein, the variable magnification optical system satisfies the following conditional expression: 0.45 < f1 / f3 < 6.00 wherein, f3: the focal length of the third lens group.

4. The variable magnification optical system according to any one of claims 1 to 3, wherein, the subsequent lens group includes a focusing lens group having a negative optical power and moving during focusing, and satisfies the following conditional expression: 0.30 < f2 / fF < 1.00 wherein, f2: the focal length of the second lens group, fF: the focal length of the focusing lens group.

5. The variable magnification optical system according to any one of claims 1 to 4, wherein, the final lens group disposed closest to the image plane in the subsequent lens group is fixed relative to the image plane during variable magnification.

6. The variable magnification optical system according to any one of claims 1 to 5, wherein, the subsequent lens group includes a focusing lens group having a negative optical power and moving during focusing and a final lens group disposed closest to the image plane, the variable magnification optical system satisfies the following conditional expression: 2.00 < |fR| / (-fF) < 100.00 wherein, fR: the focal length of the final lens group, fF: the focal length of the focusing lens group.

7. The variable magnification optical system according to any one of claims 1 to 6, wherein, the variable magnification optical system satisfies the following conditional expression: 0.15 < BFw / fw < 0.95 wherein, BFw: the back focal length of the variable magnification optical system at infinity focus in the wide-angle end state.

8. The variable magnification optical system according to any one of claims 1 to 7, wherein, the variable magnification optical system satisfies the following conditional expression: 0.08 < BFt / ft < 0.24 wherein, BFt: the back focal length of the variable magnification optical system at infinity focus in the telephoto end state.

9. The variable magnification optical system according to any one of claims 1 to 8, wherein, the subsequent lens group includes at least one lens group having a positive optical power, and satisfies the following conditional expression: 0.70 < f1 / fRP < 3.40 wherein, fRP: The focal length of the lens group with the strongest optical power among the lens groups with positive optical power included in the subsequent lens group.

10. The zoom optical system according to any one of claims 1 to 9, wherein, the zoom optical system satisfies the following conditional formula: 0.50 < Gw / Gt < 1.50 wherein, Gw: The distance from the lens surface closest to the object side of the zoom optical system to the center of gravity position of the zoom optical system in the wide-angle end state, Gt: The distance from the lens surface closest to the object side of the zoom optical system to the center of gravity position of the zoom optical system in the telephoto end state.

11. An optical device having the zoom optical system according to any one of claims 1 to 10.

12. A manufacturing method of a zoom optical system, wherein, a zoom optical system sequentially including a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with positive optical power, and a subsequent lens group with multiple lens groups from the object side is configured such that, during zooming, the first lens group and the third lens group are fixed relative to the image plane, and the intervals between adjacent lens groups change, the zoom optical system satisfies the following conditional formula: 0.24 < (TL / f1) / (ft / fw) < 0.55 wherein, TL: The distance from the lens surface closest to the object side to the image plane, f1: The focal length of the first lens group, ft: The focal length of the zoom optical system in the telephoto end state, fw: The focal length of the zoom optical system in the wide-angle end state.

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