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

Abstract

This variable magnification optical system is configured to include, in order from an object side: a front group which includes at least one lens group having negative refractive power; and a rear group which includes a plurality of lens groups and has positive refractive power as a whole, and in which a lens group arranged closest to the object side among the plurality of lens groups is a rear-side first lens group having positive refractive power, wherein during variable magnification, a front-side first lens group arranged closest to the object side among the at least one lens group of the front group is fixed to an image surface, and an interval between adjacent lens groups changes, thereby satisfying the following conditional expression.　0.01<(-fGFw) / fGR1<0.83, where fGFw is the focal length of the front group at the wide-angle end, and fGR1 is the focal length of the rear-side first lens group.

Description

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

[0001] The present disclosure relates to a variable magnification optical system, an optical instrument, and a method for manufacturing a variable magnification optical system.

[0002] A variable magnification optical system that can be used in optical devices such as photo cameras, electronic still cameras, and video cameras has been proposed (see, for example, Japanese Patent Application Laid-Open No. 2003-222294).

[0003] JP 2023-044106 A

[0004] The variable magnification optical system of the present disclosure has, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group which includes multiple lens groups and has positive refractive power overall, the lens group of the multiple lens groups being a rear-side first lens group having positive refractive power and arranged closest to the object, and during magnification variation, the front-side first lens group arranged closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and satisfies the following conditional expression: 0.01 < (-fGFw) / fGR1 < 0.83, where fGFw: focal length of the front group at the wide-angle end, fGR1: focal length of the rear-side first lens group.

[0005] The variable magnification optical system of the present disclosure has, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group which includes multiple lens groups and has positive refractive power overall, the lens group of the multiple lens groups being a rear-side first lens group having positive refractive power and which is located closest to the object side, and during magnification variation, the front-side first lens group of the at least one lens group included in the front group and which is located closest to the object side is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and satisfies the following conditional expression: 0.28 < (-fGFw) / fGRw < 0.74 where, fGFw: focal length of the front group at the wide-angle end fGRw: focal length of the rear group at the wide-angle end

[0006] The method for manufacturing a variable magnification optical system according to the present disclosure includes, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group including a plurality of lens groups having positive refractive power overall, the lens group arranged closest to the object among the plurality of lens groups being a rear-side first lens group having positive refractive power, and includes arranging the lens groups so that, during magnification variation, the front-side first lens group arranged closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and the lens groups are arranged so as to satisfy the following conditional expression: 0.01 < (-fGFw) / fGR1 < 0.83, where fGFw is the focal length of the front group at the wide-angle end, and fGR1 is the focal length of the rear-side first lens group.

[0007] The method for manufacturing a variable magnification optical system according to the present disclosure includes, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group including a plurality of lens groups having positive refractive power overall, the lens group arranged closest to the object among the plurality of lens groups being a rear-side first lens group having positive refractive power, wherein during magnification variation, the front-side first lens group arranged closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and the lens groups are arranged so as to satisfy the following conditional expression: 0.28 < (-fGFw) / fGRw < 0.74 where, fGFw: focal length of the front group at the wide-angle end fGRw: focal length of the rear group at the wide-angle end

[0008] Fig. 1(a) is a cross-sectional view of the variable magnification optical system of the first embodiment when focused on an object at infinity in the wide-angle end state, Fig. 1(b) is a cross-sectional view of the variable magnification optical system of the first embodiment in the intermediate focal length state, and Fig. 1(c) is a cross-sectional view of the variable magnification optical system of the first embodiment in the telephoto end state. Fig. 2(a) is a diagram of various aberrations of the variable magnification optical system of the first embodiment in the wide-angle end state, and Fig. 2(b) is a diagram of various aberrations of the variable magnification optical system of the first embodiment in the telephoto end state. Fig. 3(a) is a cross-sectional view of the variable magnification optical system of the second embodiment in the wide-angle end state, Fig. 3(b) is a cross-sectional view of the variable magnification optical system of the second embodiment in the intermediate focal length state, and Fig. 3(c) is a cross-sectional view of the variable magnification optical system of the second embodiment in the telephoto end state. Fig. 4(a) is a diagram of various aberrations of the variable magnification optical system of the second embodiment in the wide-angle end state, and Fig. 4(b) is a diagram of various aberrations of the variable magnification optical system of the second embodiment in the telephoto end state. Figure 5(a) is a cross-sectional view of the variable magnification optical system of the third embodiment in the wide-angle end state, Figure 5(b) is a cross-sectional view of the variable magnification optical system of the third embodiment in the intermediate focal length state, and Figure 5(c) is a cross-sectional view of the variable magnification optical system of the third embodiment in the telephoto end state. Figure 6(a) is a diagram of various aberrations of the variable magnification optical system of the third embodiment in the wide-angle end state, and Figure 6(b) is a diagram of various aberrations of the variable magnification optical system of the third embodiment in the telephoto end state. Figure 7(a) is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the wide-angle end state, Figure 7(b) is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the intermediate focal length state, and Figure 7(c) is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the telephoto end state. Figure 8(a) is a diagram of various aberrations of the variable magnification optical system of the fourth embodiment in the wide-angle end state, and Figure 8(b) is a diagram of various aberrations of the variable magnification optical system of the fourth embodiment in the telephoto end state. Fig. 9(a) is a cross-sectional view of the variable magnification optical system of Example 5 in the wide-angle end state, Fig. 9(b) is a cross-sectional view of the variable magnification optical system of Example 5 in the intermediate focal length state, and Fig. 9(c) is a cross-sectional view of the variable magnification optical system of Example 5 in the telephoto end state. Fig. 10(a) is a diagram of various aberrations of the variable magnification optical system of Example 5 in the wide-angle end state, and Fig. 10(b) is a diagram of various aberrations of the variable magnification optical system of Example 5 in the telephoto end state. Fig. 11(a) is a cross-sectional view of the variable magnification optical system of Example 6 in the wide-angle end state, Fig. 11(b) is a cross-sectional view of the variable magnification optical system of Example 6 in the intermediate focal length state, and Fig. 11(c) is a cross-sectional view of the variable magnification optical system of Example 6 in the telephoto end state.Fig. 12(a) is a diagram showing various aberrations of the variable magnification optical system of Example 6 in the wide-angle end state, and Fig. 12(b) is a diagram showing various aberrations of the variable magnification optical system of Example 6 in the telephoto end state. Fig. 13(a) is a cross-sectional view of the variable magnification optical system of Example 7 in the wide-angle end state, Fig. 13(b) is a cross-sectional view of the variable magnification optical system of Example 7 in the intermediate focal length state, and Fig. 13(c) is a cross-sectional view of the variable magnification optical system of Example 7 in the telephoto end state. Fig. 14(a) is a diagram showing various aberrations of the variable magnification optical system of Example 7 in the wide-angle end state, and Fig. 14(b) is a diagram showing various aberrations of the variable magnification optical system of Example 7 in the telephoto end state. Fig. 15(a) is a cross-sectional view of the variable magnification optical system of Example 8 in the wide-angle end state, Fig. 15(b) is a cross-sectional view of the variable magnification optical system of Example 8 in the intermediate focal length state, and Fig. 15(c) is a cross-sectional view of the variable magnification optical system of Example 8 in the telephoto end state. Fig. 16(a) is a diagram showing various aberrations of the variable magnification optical system of Example 8 in the wide-angle end state, and Fig. 16(b) is a diagram showing various aberrations of the variable magnification optical system of Example 8 in the telephoto end state. Fig. 17(a) is a cross-sectional view of the variable magnification optical system of Example 9 in the wide-angle end state, Fig. 17(b) is a cross-sectional view of the variable magnification optical system of Example 9 in the intermediate focal length state, and Fig. 17(c) is a cross-sectional view of the variable magnification optical system of Example 9 in the telephoto end state. Fig. 18(a) is a diagram showing various aberrations of the variable magnification optical system of Example 9 in the wide-angle end state, and Fig. 18(b) is a diagram showing various aberrations of the variable magnification optical system of Example 9 in the telephoto end state. Fig. 19(a) is a cross-sectional view of the variable magnification optical system of Example 10 in the wide-angle end state, Fig. 19(b) is a cross-sectional view of the variable magnification optical system of Example 10 in the intermediate focal length state, and Fig. 19(c) is a cross-sectional view of the variable magnification optical system of Example 10 in the telephoto end state. Fig. 20(a) is a diagram showing various aberrations of the variable magnification optical system of Example 10 in the wide-angle end state, and Fig. 20(b) is a diagram showing various aberrations of the variable magnification optical system of Example 10 in the telephoto end state. Fig. 21(a) is a cross-sectional view of the variable magnification optical system of Example 11 in the wide-angle end state, Fig. 21(b) is a cross-sectional view of the variable magnification optical system of Example 11 in the intermediate focal length state, and Fig. 21(c) is a cross-sectional view of the variable magnification optical system of Example 11 in the telephoto end state. Fig. 22(a) is a diagram showing various aberrations of the variable magnification optical system of Example 11 in the wide-angle end state, and Fig. 22(b) is a diagram showing various aberrations of the variable magnification optical system of Example 11 in the telephoto end state.Fig. 23(a) is a cross-sectional view of the variable magnification optical system of Example 12 in the wide-angle end state, Fig. 23(b) is a cross-sectional view of the variable magnification optical system of Example 12 in the intermediate focal length state, and Fig. 23(c) is a cross-sectional view of the variable magnification optical system of Example 12 in the telephoto end state. Fig. 24(a) is a diagram showing various aberrations of the variable magnification optical system of Example 12 in the wide-angle end state, and Fig. 24(b) is a diagram showing various aberrations of the variable magnification optical system of Example 12 in the telephoto end state. Fig. 25(a) is a cross-sectional view of the variable magnification optical system of Example 13 in the wide-angle end state, Fig. 25(b) is a cross-sectional view of the variable magnification optical system of Example 13 in the intermediate focal length state, and Fig. 25(c) is a cross-sectional view of the variable magnification optical system of Example 13 in the telephoto end state. Fig. 26(a) is a diagram showing various aberrations of the variable magnification optical system of Example 13 in the wide-angle end state, and Fig. 26(b) is a diagram showing various aberrations of the variable magnification optical system of Example 13 in the telephoto end state. Fig. 27(a) is a cross-sectional view of the variable magnification optical system of Example 14 in the wide-angle end state, Fig. 27(b) is a cross-sectional view of the variable magnification optical system of Example 14 in the intermediate focal length state, and Fig. 27(c) is a cross-sectional view of the variable magnification optical system of Example 14 in the telephoto end state. Fig. 28(a) is a diagram showing various aberrations of the variable magnification optical system of Example 14 in the wide-angle end state, and Fig. 28(b) is a diagram showing various aberrations of the variable magnification optical system of Example 14 in the telephoto end state. Fig. 29 is a schematic diagram of an optical device equipped with the variable magnification optical system of this embodiment. Fig. 30 is a flowchart outlining a method for manufacturing the variable magnification optical system of this embodiment.

[0009] Hereinafter, a variable magnification optical system and an optical apparatus according to an embodiment of the present application will be described.

[0010] The variable magnification optical system of this embodiment has, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group which includes multiple lens groups and has positive refractive power overall, the lens group of the multiple lens groups being the rear first lens group which is located closest to the object side and has positive refractive power, and during magnification variation, the front first lens group which is located closest to the object side among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and satisfies the following conditional expression: (1) 0.01 < (-fGFw) / fGR1 < 0.83 where, fGFw: focal length of the front group at the wide-angle end fGR1: focal length of the rear first lens group

[0011] The variable magnification optical system of this embodiment can achieve a sufficiently wide angle of view by including a front group consisting of at least one lens group each having negative refractive power.

[0012] The variable magnification optical system of this embodiment includes a rear group having a positive refractive power as a whole and including a plurality of lens groups, and thus can appropriately correct various aberrations over the entire range from the wide-angle end to the telephoto end.

[0013] In the variable magnification optical system of this embodiment, the lens group arranged closest to the object among the plurality of lens groups has positive refractive power, so that various aberrations can be appropriately corrected.

[0014] Conditional expression (1) defines the ratio of the focal length of the front lens group to the focal length of the first rear lens group at the wide-angle end. By satisfying conditional expression (1), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0015] In the variable magnification optical system of this embodiment, if the value of conditional expression (1) exceeds the upper limit, the refractive power of the rear first lens group becomes too strong, making it difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0016] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (1) to 0.83. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (1) to 0.80, 0.70, 0.60, 0.55, 0.52, or even 0.50.

[0017] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (1) falls below the lower limit, the refractive power of the front group becomes too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0018] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (1) to 0.01. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (1) to 0.06, 0.11, 0.16, 0.21, or even 0.26.

[0019] The variable magnification optical system of this embodiment has, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group which includes a plurality of lens groups and has positive refractive power overall, the lens group of the plurality of lens groups being a rear-side first lens group having positive refractive power and which is located closest to the object side, and during magnification variation, the front-side first lens group of the at least one lens group included in the front group and which is located closest to the object side is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and satisfies the following conditional expression (2): 0.28 < (-fGFw) / fGRw < 0.74, where fGRw: focal length of the rear group at the wide-angle end.

[0020] Conditional expression (2) defines the ratio between the focal length of the front group at the wide-angle end and the focal length of the rear group at the wide-angle end. By satisfying conditional expression (2), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0021] In the variable magnification optical system of this embodiment, if the value of conditional expression (2) exceeds the upper limit, the refractive power of the rear group becomes too strong, making it difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0022] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (2) to 0.74. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.72, 0.70, 0.68, or even 0.67.

[0023] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (2) falls below the lower limit, the refractive power of the front group becomes too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0024] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (2) to 0.28. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.32, 0.36, 0.39, 0.44, or even 0.46.

[0025] In the variable magnification optical system of this embodiment, it is preferable that the rear group has at least four lens groups, including at least one lens group having negative refractive power.

[0026] With this configuration, the variable magnification optical system of this embodiment is small in size and has high performance.

[0027] In the variable magnification optical system of this embodiment, it is preferable that the rear group has an aperture stop and that the following conditional expression be satisfied: (3) 0.01 < fwsfp / fwsrp < 3.50, where fwsfp is the composite focal length from the lens in the rear first lens group closest to the object at the wide-angle end to the aperture stop, and fwsrp is the composite focal length from the aperture stop at the wide-angle end to the lens located closest to the object in the lens group with negative refractive power located closest to the object on the image plane side of the aperture stop.

[0028] Conditional expression (3) defines the ratio, at the wide-angle end, between the composite focal length from the lens closest to the object in the first rear lens group to the aperture stop, and the composite focal length from the aperture stop to the lens located closest to the object in the lens group having negative refractive power that is located closest to the object on the image plane side of the aperture stop. By satisfying conditional expression (3), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0029] In the variable magnification optical system of this embodiment, if the value of conditional expression (3) exceeds the upper limit, the refractive power from the aperture stop at the wide-angle end to the lens located on the object side of the lens group having negative refractive power that is located closest to the object on the image plane side of the aperture stop will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration and coma.

[0030] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (3) to 3.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (3) to 3.30, 3.10, 2.90, 2.85, 2.80, or even 2.75.

[0031] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (3) falls below the lower limit, the refractive power from the lens closest to the object in the first rear lens group to the aperture stop at the wide-angle end will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0032] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (3) to 0.01. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.10, 0.20, 0.30, 0.40, 0.50, or even 0.60.

[0033] It is preferable that the variable magnification optical system of this embodiment satisfies the following condition (4): -1.10<fGL2 / fGL1<1.50, where fGL2 is the focal length of the lens group arranged adjacent to the lens group arranged closest to the image plane on the object side, and fGL1 is the focal length of the lens group arranged closest to the image plane.

[0034] Conditional expression (4) defines the ratio between the focal length of the lens group located adjacent to the lens group located closest to the image plane on the object side and the focal length of the lens group located closest to the image plane. By satisfying conditional expression (4), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0035] In the variable magnification optical system of this embodiment, if the value of conditional expression (4) is not between the lower limit and the upper limit, the refractive power of the lens group located closest to the image plane will be too strong, making it difficult to properly correct field curvature.

[0036] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (4) to 1.50. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (4) to 1.30, 1.15, 1.00, 0.90, 0.75, 0.60, or even 0.50.

[0037] Furthermore, in the variable magnification optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (4) to -1.10. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (4) to -1.00, -0.95, -0.90, -0.85, -0.78, or even -0.70.

[0038] It is preferable that the variable magnification optical system of this embodiment satisfies the following condition (5): 0.05<f1 / f2<1.00, where f1 is the focal length of the lens located closest to the object, and f2 is the focal length of the lens located adjacent to the lens located closest to the object on the image plane side.

[0039] Conditional expression (5) defines the ratio between the focal length of the lens closest to the object and the focal length of the lens closest to the object, which is adjacent to the lens closest to the object and on the image plane side of the lens closest to the object. By satisfying conditional expression (5), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0040] In the variable magnification optical system of this embodiment, if the value of conditional expression (5) exceeds the upper limit, the refractive power of the lens located adjacent to the lens located closest to the object on the image plane side will be too strong, making it difficult to appropriately correct various aberrations such as coma and field curvature.

[0041] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (5) to 1.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 0.90, 0.80, 0.70, 0.65, 0.60, or even 0.55.

[0042] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (5) falls below the lower limit, the refractive power of the lens located closest to the object becomes too strong, making it difficult to appropriately correct various aberrations such as coma and field curvature.

[0043] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (5) to 0.05. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (5) to 0.08, 0.10, 0.13, 0.15, 0.17, or even 0.19.

[0044] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (6): 0.01<fw / BFw<1.70, where fw is the focal length of the variable magnification optical system at the wide-angle end, and BFw is the back focal length at the wide-angle end.

[0045] Conditional expression (6) defines the ratio between the focal length and the back focus of the variable magnification optical system at the wide-angle end. By satisfying conditional expression (6), the variable magnification optical system of this embodiment becomes small and high-performance.

[0046] In the variable magnification optical system of this embodiment, if the value of conditional expression (6) is not between the lower limit and the upper limit, it will be difficult to achieve a compact, high-performance optical system.

[0047] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (6) to 1.70. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (6) to 1.65, 1.60, 1.55, 1.50, 1.45, 1.40, 1.35, or even 1.30.

[0048] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (6) to 0.01. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (6) to 0.15, 0.30, 0.40, 0.50, 0.65, or even 0.80.

[0049] In the variable magnification optical system of this embodiment, it is preferable that the rear group has an aperture stop and that the following conditional expression be satisfied: (7) 0.01<fGS0 / (-fGS1n)<5.00, where fGS0 is the focal length of the lens group that is located adjacent to the lens group that is located closest to the object among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop, and fGS1n is the focal length of the lens group that is located closest to the object among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop.

[0050] Conditional expression (7) defines the ratio of the focal length of the lens group that is located closest to the object, to the focal length of the lens group that is located closest to the object, among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop. By satisfying conditional expression (7), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0051] In the variable magnification optical system of this embodiment, if the value of conditional expression (7) exceeds the upper limit, the refractive power of the lens group that is located closest to the object among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0052] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (7) to 5.00. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (7) to 4.50, 4.20, 2.50, 2.30, 2.15, 2.00, 1.75, or even 1.50.

[0053] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (7) falls below the lower limit, the refractive power of the lens group that is located adjacent to the lens group that is located closest to the object among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0054] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (7) to 0.01. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (7) to 0.05, 0.10, 0.15, 0.20, 0.24, or even 0.28.

[0055] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (8): −1.00<BFw / fGL1<1.00.

[0056] Conditional expression (8) defines the ratio between the back focus at the wide-angle end and the focal length of the lens group located closest to the image plane. By satisfying conditional expression (8), the variable magnification optical system of this embodiment can be made compact and can appropriately correct various aberrations.

[0057] In the variable magnification optical system of this embodiment, if the value of conditional expression (8) exceeds the upper limit, the positive refractive power of the lens group arranged closest to the image plane becomes too strong, making it difficult to correct curvature of field. In addition, the back focus of the variable magnification optical system becomes large, resulting in an increase in the overall size.

[0058] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (8) to 1.00. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (8) to 0.90, 0.75, 0.60, 0.50, 0.40, 0.35, or even 0.30.

[0059] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (8) is below the lower limit, the negative refractive power of the lens group arranged closest to the image plane becomes too strong, making it difficult to correct curvature of field. Also, the back focus of the variable magnification optical system becomes large, resulting in an increase in the overall size.

[0060] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (8) to -1.00. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (8) to -0.85, -0.70, -0.60, -0.50, -0.40, -0.30, -0.25, -0.20, or even -0.15.

[0061] In the variable magnification optical system of this embodiment, it is preferable that the front group has a positive lens arranged closest to the image plane, and a negative lens arranged adjacent to the positive lens on the object side.

[0062] The variable magnification optical system of this embodiment has such a configuration, and can appropriately correct various aberrations such as coma and curvature of field, and can also be made compact and high-performance.

[0063] It is preferable that the variable magnification optical system of this embodiment satisfies the following condition (9): -0.50<(-f1) / fni<0.18, where fni is the composite focal length of the positive lens and negative lens that are adjacently arranged on the most image side of the front group.

[0064] Conditional expression (9) defines the ratio between the focal length of the lens closest to the object and the composite focal length of the positive lens and negative lens closest to the image plane in the front group. By satisfying conditional expression (9), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0065] In the variable magnification optical system of this embodiment, if the value of conditional expression (9) exceeds the upper limit, the positive refractive power of the positive lens and negative lens arranged adjacent to each other and closest to the image side in the front group will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0066] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (9) to 0.18. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.17, 0.16, 0.15, 0.14, or even 0.13.

[0067] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (9) is below the lower limit, the negative refractive power of the positive lens and the negative lens arranged adjacent to each other on the most image side of the front group will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature. Also, the refractive power of the lens arranged closest to the object side will be too strong, making it difficult to appropriately correct various aberrations such as coma and field curvature.

[0068] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (9) to -0.50. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (9) to -0.40, -0.35, -0.30, -0.25, -0.20, or even -0.15.

[0069] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (10): −1.50<(−f2) / fni<0.70

[0070] Conditional expression (10) defines the ratio between the focal length of the lens located adjacent to the lens located closest to the object on the image plane side and the composite focal length of the positive lens and negative lens located adjacent to each other on the image plane side in the front group. By satisfying conditional expression (10), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0071] In the variable magnification optical system of this embodiment, if the value of conditional expression (10) exceeds the upper limit, the positive refractive power of the positive lens and negative lens arranged adjacent to each other and closest to the image surface in the front group will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0072] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (10) to 0.70. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (10) to 0.65, 0.62, 0.60, or even 0.56.

[0073] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (10) is below the lower limit, the negative refractive power of the positive lens and the negative lens arranged adjacent to each other on the most image side of the front group will be too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and curvature of field. Also, the refractive power of the lens arranged adjacent to the image side of the lens arranged closest to the object side will be too strong, making it difficult to appropriately correct various aberrations such as coma and curvature of field.

[0074] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (10) to -1.50. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (10) to -1.00, -0.80, -0.50, -0.40, -0.35, -0.30, -0.25, -0.20, or even -0.18.

[0075] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (11): 2.20<f2 / fG1<13.00, where fG1 is the focal length of the front first lens unit.

[0076] Conditional expression (11) defines the ratio between the focal length of the lens located adjacent to the lens located closest to the object on the image plane side and the focal length of the front first lens group. By satisfying conditional expression (11), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0077] In the variable magnification optical system of this embodiment, if the value of conditional expression (11) exceeds the upper limit, the refractive power of the front first lens group becomes too strong, making it difficult to appropriately correct various aberrations such as coma and curvature of field.

[0078] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (11) to 13.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (11) to 11.00, 10.00, 9.00, 8.00, or even 7.00.

[0079] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (11) falls below the lower limit, the refractive power of the lens arranged adjacent to the lens arranged closest to the object on the image plane side will be too strong, making it difficult to appropriately correct various aberrations such as coma and field curvature.

[0080] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (11) to 2.20. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (11) to 2.40, 2.60, 2.80, 3.00, 3.10, 3.20, 3.30, 3.40, or even 3.50.

[0081] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (12): 1.10<f1 / fG1<5.00.

[0082] Conditional expression (12) defines the ratio between the focal length of the lens closest to the object and the focal length of the first front lens group. By satisfying conditional expression (12), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0083] In the variable magnification optical system of this embodiment, if the value of conditional expression (12) exceeds the upper limit, the refractive power of the front first lens group becomes too strong, making it difficult to appropriately correct various aberrations such as coma and curvature of field.

[0084] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (12) to 5.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (12) to 4.50, 4.00, 3.70, 3.20, 2.80, or even 2.50.

[0085] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (12) falls below the lower limit, the refractive power of the lens located closest to the object becomes too strong, making it difficult to appropriately correct various aberrations such as coma and field curvature.

[0086] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (12) to 1.10. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (12) to 1.13, 1.16, 1.20, 1.22, or even 1.25.

[0087] In the variable magnification optical system of this embodiment, it is preferable that the rear group has an aperture stop, and that it has at least one lens group with positive refractive power and one lens group with negative refractive power on the image plane side of a lens group that includes a lens that is arranged adjacent to the image plane side of the aperture stop.

[0088] The variable magnification optical system of this embodiment has such a configuration, and can achieve high optical performance over the entire range from the wide-angle end to the telephoto end.

[0089] In the variable magnification optical system of this embodiment, it is preferable that the rear group has at least two cemented lenses each having a positive lens and a negative lens.

[0090] The variable magnification optical system of this embodiment has such a configuration, which makes it possible to appropriately correct chromatic aberration, and also makes it possible to achieve a compact, high-performance optical system.

[0091] The variable magnification optical system of this embodiment preferably has a first focusing lens group that moves during focusing and has at least one lens, and a second focusing lens group that is arranged on the image plane side of the first focusing lens group, moves during focusing along a locus different from that of the first focusing lens group, and has at least one lens, and satisfies the following conditional expression (13): 0.01 < |fo1 / fo2| < 5.00, where, fo1: focal length of the first focusing lens group, fo2: focal length of the second focusing lens group.

[0092] Conditional expression (13) defines the ratio between the focal length of the first focusing lens group and the focal length of the second focusing lens group. By satisfying conditional expression (13), the variable magnification optical system of this embodiment can appropriately correct various aberrations.

[0093] In the variable magnification optical system of this embodiment, if the value of conditional expression (13) exceeds the upper limit, the refractive power of the second focusing lens group becomes too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0094] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (13) to 5.00. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (13) to 4.50, 4.00, 3.50, 3.00, or even 2.50.

[0095] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (13) falls below the lower limit, the refractive power of the first focusing lens group becomes too strong, making it difficult to appropriately correct various aberrations such as spherical aberration, coma, and field curvature.

[0096] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (13) to 0.01. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (13) to 0.03, 0.05, 0.08, or even 0.10.

[0097] The variable magnification optical system of this embodiment preferably includes an aperture stop and a focusing lens group having at least one lens, which moves during focusing, on the object side of the aperture stop.

[0098] The variable magnification optical system of this embodiment has such a configuration, and can provide good close-range performance, and can also be made compact and high-performance.

[0099] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (14): 50.00°<ωw<85.00°, where ωw is the half angle of view of the variable magnification optical system at the wide-angle end.

[0100] Conditional expression (14) defines the half angle of view of the variable magnification optical system at the wide-angle end. By satisfying conditional expression (14), the variable magnification optical system of this embodiment can be made compact and high-performance while having a sufficiently wide field of view.

[0101] In the variable magnification optical system of this embodiment, if the value of conditional expression (14) exceeds the upper limit, it becomes difficult to make the variable magnification optical system small and high performance.

[0102] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (14) to 85.00°. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (14) to 80.00°, 75.00°, 70.00°, 65.00°, or even 60.00°.

[0103] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (14) falls below the lower limit, it becomes difficult to sufficiently widen the field of view of the variable magnification optical system.

[0104] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (14) to 50.00°. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (14) to 52.00°, 54.00°, 56.00°, or even 57.00°.

[0105] It is preferable that the variable magnification optical system of this embodiment satisfies the following conditional expression (15): 1.40<Fnow<4.20, where Fnow is the F-number of the variable magnification optical system at the wide-angle end.

[0106] Conditional expression (15) defines the F-number of the variable magnification optical system at the wide-angle end. By satisfying conditional expression (15), the variable magnification optical system of this embodiment can obtain a sufficiently bright image and can be made compact.

[0107] In the variable magnification optical system of this embodiment, if the value of conditional expression (15) exceeds the upper limit, a sufficiently bright image cannot be obtained.

[0108] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (15) to 4.20. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (15) to 3.90, 3.75, 3.50, 3.30, 3.15, or even 3.00.

[0109] Furthermore, in the variable magnification optical system of this embodiment, if the value of conditional expression (15) falls below the lower limit, it becomes difficult to achieve size reduction.

[0110] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the lower limit of conditional expression (15) to 1.40. In order to more reliably achieve the effect of this embodiment, it is preferable to set the lower limit of conditional expression (15) to 1.60, 1.90, 2.20, 2.40, 2.60, or even 2.80.

[0111] It is preferable that the variable magnification optical system of this embodiment satisfies both of the following conditional expressions: (16) 0.60<ndp / ndn<1.50 (17) 0.20<νdp / νdn<1.00 where, ndp: refractive index for the d-line of the positive lens included in the cemented lens located closest to the image surface ndn: refractive index for the d-line of the negative lens included in the cemented lens located closest to the image surface νdp: Abbe number based on the d-line of the positive lens included in the cemented lens located closest to the image surface νdn: Abbe number based on the d-line of the negative lens included in the cemented lens located closest to the image surface

[0112] Conditional expression (16) defines the ratio of the refractive index for the d-line of the positive lens included in the cemented lens located closest to the image surface to the refractive index for the d-line of the negative lens included in the cemented lens located closest to the image surface. Conditional expression (17) defines the ratio of the Abbe number, based on the d-line of the positive lens included in the cemented lens located closest to the image surface, to the Abbe number, based on the d-line of the negative lens included in the cemented lens located closest to the image surface. The variable magnification optical system of this embodiment can appropriately correct various aberrations by satisfying both conditional expressions (16) and (17).

[0113] In the variable magnification optical system of this embodiment, if the value of conditional expression (16) is not between the lower limit and the upper limit, it becomes difficult to appropriately correct various aberrations such as coma and curvature of field.

[0114] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (16) to 1.50. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (16) to 1.40, 1.30, 1.20, or even 1.10.

[0115] Furthermore, in the variable magnification optical system of this embodiment, the effect of this embodiment can be made more certain by setting the lower limit of conditional expression (16) to 0.60. In order to make the effect of this embodiment more certain, it is preferable to set the lower limit of conditional expression (16) to 0.68, 0.75, 0.82, or even 0.90.

[0116] In the variable magnification optical system of this embodiment, if the value of conditional expression (17) is not between the lower limit and the upper limit, it becomes difficult to appropriately correct chromatic aberration.

[0117] In the variable magnification optical system of this embodiment, the effect of this embodiment can be more reliably achieved by setting the upper limit of conditional expression (17) to 1.00. In order to more reliably achieve the effect of this embodiment, it is preferable to set the upper limit of conditional expression (17) to 0.95, 0.90, 0.85, or even 0.80.

[0118] In the variable magnification optical system of this embodiment, the effect of this embodiment can be further ensured by setting the lower limit of conditional expression (17) to 0.20. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (17) to 0.25, 0.30, 0.35, 0.40, or even 0.45.

[0119] In the variable magnification optical system of this embodiment, it is preferable that the rear group comprises at least six lens groups.

[0120] The variable magnification optical system of this embodiment has such a configuration, and is therefore able to achieve high optical performance over the entire range from the wide-angle end to the telephoto end.

[0121] The variable magnification optical system of this embodiment preferably includes at least three lens groups each consisting of one lens component.

[0122] The variable magnification optical system of this embodiment has such a configuration, which increases the degree of freedom in changing the spacing between each lens when changing magnification, and allows each lens group to be made lightweight, resulting in a compact overall system and high optical performance.

[0123] With the above configuration, when zooming, the lens group arranged closest to the object side is fixed with respect to the image plane, making it possible to realize a variable-magnification optical system that is compact and has high optical performance.

[0124] The optical apparatus of this embodiment has the variable magnification optical system configured as described above. As a result, the optical apparatus of this embodiment has a lens group arranged closest to the object side fixed with respect to the image plane, and is small in size and has high optical performance.

[0125] The manufacturing method of a variable magnification optical system of this embodiment is a manufacturing method of a variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group including a plurality of lens groups having positive refractive power overall, the lens group arranged closest to the object among the plurality of lens groups being a rear-side first lens group having positive refractive power, and includes arranging the lens groups so that, during magnification variation, the front-side first lens group arranged closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and the lens groups are arranged so as to satisfy the following conditional formula: (1) 0.01 < (-fGFw) / fGR1 < 0.83 where, fGFw: focal length of the front group at the wide-angle end fGR1: focal length of the rear-side first lens group

[0126] The manufacturing method of a variable magnification optical system of this embodiment is a manufacturing method of a variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group including a plurality of lens groups having positive refractive power overall, the lens group arranged closest to the object among the plurality of lens groups being a rear-side first lens group having positive refractive power, and includes arranging the lens groups so that, during magnification variation, the front-side first lens group arranged closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, the spacing between adjacent lens groups changes, and the lens groups are arranged so as to satisfy the following conditional expression: (2) 0.28 < (-fGFw) / fGRw < 0.74 where, fGFw: focal length of the front group at the wide-angle end fGRw: focal length of the rear group at the wide-angle end

[0127] By using such a manufacturing method for a variable magnification optical system, it is possible to manufacture a small variable magnification optical system having high optical performance, in which the lens group arranged closest to the object is fixed relative to the image plane during magnification variation.

[0128] Numerical Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

[0129] (First Embodiment) FIG. 1(a) is a cross-sectional view of the variable magnification optical system of the first embodiment in the wide-angle end state, FIG. 1(b) is a cross-sectional view of the variable magnification optical system of the first embodiment in the intermediate focal length state, and FIG. 1(c) is a cross-sectional view of the variable magnification optical system of the first embodiment in the telephoto end state.

[0130] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive 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 positive refractive power, a sixth lens group G6 having positive refractive power, a seventh lens group G7 having negative refractive power, and an eighth lens group G8 having negative refractive power.

[0131] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0132] The second lens group G2 is made up of a biconvex positive lens L5.

[0133] The third lens group G3 is composed of a positive meniscus lens L6 with its convex surface facing the object side.

[0134] The fourth lens group G4 is made up of a negative plano-concave lens L7 with its concave surface facing the object side.

[0135] The fifth lens group G5 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9.

[0136] The sixth lens group G6 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L10 and a biconcave negative lens L11, and a biconvex positive lens L12.

[0137] The seventh lens group G7 is composed of a cemented negative lens made up of a meniscus positive lens L13 with its concave surface facing the object side and a biconcave negative lens L14.

[0138] The eighth lens group G8 is composed of, in order from the object side, a negative meniscus lens L15 with its concave surface facing the object side, and a positive biconvex lens L16.

[0139] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0140] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the eighth lens group G8 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0141] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the fourth lens group G4 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 and the fourth lens group G4 are each moved from the object side to the image plane side. The second lens group G2 corresponds to the first focusing lens group, and the fourth lens group G4 corresponds to the second focusing lens group.

[0142] Table 1 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0143] In the [Overall Specifications], f indicates the total system focal length, FNo indicates the F-number, TL indicates the distance in air equivalent length from the lens surface closest to the object to the image plane, BF indicates the back focus in air equivalent length, Y indicates the maximum image height, and ω indicates the half angle of view (degrees). For each item, W indicates the value at the wide-angle end, M indicates the value at the mid-focal length, and T indicates the value at the telephoto end. These values ​​listed in the [Overall Specifications] are for the d-line (wavelength 587.6 nm).

[0144] In the [Lens Specifications] in Table 1, m is the order of the optical surface counted from the object side, r is the radius of curvature, d is the surface spacing, n(d) is the refractive index for the d-line, and νd is the Abbe number for the d-line. A radius of curvature r=∞ indicates a flat surface. Additionally, in the [Lens Specifications], optical surfaces marked with an "*" are aspherical.

[0145] 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.

[0146] The aspherical surface is expressed by the following formula (a), where y is the height in the direction perpendicular to the optical axis, S(y) is the distance (amount of sag) along the optical axis from the tangent plane of the vertex of each aspherical surface at height y to each aspherical surface, r is the radius of curvature (paraxial radius of curvature) of the reference spherical surface, K is the conic constant, and An is the n-th order aspherical coefficient. In each example, the second order aspherical coefficient A2 is 0. Also, "En" is expressed as "×10 －ｎ " indicates.

[0147] (a) S(y) = (y ２ / r) / 1 + (1-K×y ２ / r ２ ) １／２ + A4×y ４ + A6×y ６ + A8×y ８ + A10×y １０ + A12×y １２

[0148] The units of focal length, radius of curvature, and other lengths listed in Table 1 are "mm." However, this is not limited to this, as variable magnification optical systems can achieve the same optical performance even when proportionally enlarged or reduced.

[0149] The symbols in Table 1 described above are similarly used in tables of other examples to be described later.

[0150] (Table 1) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.145 51.550 42.181 Y 21.700 21.700 21.700 TL 125.655 125.655 125.655 BF 10.255 13.033 21.249 [Lens specifications] m r d n(d) νd * 1) 153.5884 5.900 1.61875 63.73 * 2) 17.3340 10.625 3) 69.9068 2.700 1.82098 42.50 * 4) 30.7179 9.363 5) -61.5111 1.400 1.49782 82.57 6) 23.6106 6.034 1.85026 32.35 7) 96.3340 D7 * 8) 65.8344 3.193 1.69343 53.30 * 9) -93.0477 D9 10) 32.2088 2.518 1.73800 32.33 11) 68.8419 D11 12) -69.6093 1.200 1.90366 31.27 13) ∞ D13 14>∞ 0.953 (Aperture stop) 15) 51.7436 1.200 1.95000 29.37 16) 20.6295 6.026 1.55332 71.68 17) -34.8553 D17 18) 30.8585 5.508 1.49782 82.57 19) -24.3124 1.200 1.83481 42.73 20) 226.6420 0.100 21) 31.6944 5.794 1.51823 58.82 22) -31.8802 D22 23) -3630.5209 3.362 1.94594 17.98 24) -35.0000 1.200 1.90265 35.77 25) 33.8158 D25 *26) -83.3426 1.500 1.85135 40.10 *27) -500.0000 2.143 28) 494.6746 3.525 1.49782 82.57 29) -78.1684 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 4.140E-06 -4.100E-09 4.167E-12 -2.268E-15 7.068E-19 2) 0.0749 -2.034E-06 7.591E-09 -1.527E-11 -1.965E-13 3.569E-16 4) 0.9294 2.337E-05 7.344E-09 2.911E-10 -5.028E-13 2.121E-15 8) 1.0000 7.653E-07 6.073E-09 1.640E-10 -1.274E-12 1.745E-14 9) 1.0000 1.966E-06 1.927E-08 -5.509E-11 6.510E-13 1.247E-14 26) 1.0000 -1.571E-04 -1.302E-07 5.928E-09 -1.830E-11 4.170E-15 27) 1.0000 -1.203E-04 1.337E-07 4.669E-09 -1.920E-11 2.355E-14 [Focal length data for each group] Group First surface Focal length G1 1 -17.911 G2 8 56.062 G3 10 79.690 G4 12 -77.030 G5 14 66.297 G6 18 34.113 G7 23 -38.893 G8 26 -1225.348 [Variable distance data] When focused at infinity When focused at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 16.342 11.026 1.500 17.824 12.885 3.413 D9 2.994 5.574 7.671 1.512 3.715 5.758 D11 2.783 2.795 3.594 3.576 2.559 2.810 D13 6.988 4.395 1.500 6.194 4.632 2.283 D17 1.500 4.080 6.177 1.500 4.080 6.177 D22 1.500 1.785 3.673 1.500 1.785 3.673 D25 7.850 7.522 4.847 7.850 7.522 4.847 BF 10.255 13.033 21.249 10.255 13.033 21.249.

[0151] FIG. 2A is a diagram showing various aberrations of the variable magnification optical system of the first embodiment in the wide-angle end state, and FIG. 2B is a diagram showing various aberrations of the variable magnification optical system of the first embodiment in the telephoto end state.

[0152] In each aberration diagram, FNO indicates the F-number, and Y indicates the image height. More specifically, spherical aberration diagrams indicate the F-number value corresponding to the maximum aperture, astigmatism diagrams and distortion diagrams indicate the maximum image height, and coma diagrams indicate the value of each image height. d indicates the d-line, and g indicates the g-line (wavelength 435.8 nm). In astigmatism diagrams, the solid line indicates the sagittal image plane, and the dashed line indicates the meridional image plane. The same symbols as those used in the aberration diagrams of this embodiment are used in the aberration diagrams of other embodiments described below.

[0153] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0154] (Second Example) Figure 3(a) is a cross-sectional view of the variable magnification optical system of the second example in the wide-angle end state, Figure 3(b) is a cross-sectional view of the variable magnification optical system of the second example in the intermediate focal length state, and Figure 3(c) is a cross-sectional view of the variable magnification optical system of the second example in the telephoto end state.

[0155] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 positive refractive power.

[0156] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0157] The second lens group G2 is made up of a biconvex positive lens L5.

[0158] The third lens group G3 is made up of a negative meniscus lens L6 with its concave surface facing the object side.

[0159] The fourth lens group G4 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L7 with its convex surface facing the object side and a biconvex positive lens L8.

[0160] The fifth lens group G5 is composed of, in order from the object side, a cemented positive lens of a biconvex positive lens L9 and a meniscus negative lens L10 with its concave surface facing the object side, and a biconvex positive lens L11.

[0161] The sixth lens group G6 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L12 and a biconcave negative lens L13, and a meniscus negative lens L14 with its concave surface facing the object side.

[0162] The seventh lens group G7 is composed of a positive lens L15 having a plano-convex shape with its convex surface facing the image surface side.

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

[0164] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0165] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the third lens group G3 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the third lens group G3 corresponds to the second focusing lens group.

[0166] Table 2 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0167] (Table 2) [All elements] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.382 51.606 41.586 Y 21.700 21.700 21.700 TL 124.055 124.055 124.055 BF 11.243 10.857 11.253 [All elements] m r d n(d) νd * 1) 87.0282 2.500 1.61875 63.73 * 2) 16.6509 11.191 3) 82.3573 1.600 8) 38.5131 3.353 1.69343 53.30 9) -609.7736 D9 10) -49.4455 1.311 1.59319 67.90 11) -69.4969 D11 12) ∞ 0.800 (Open twist) 13) 44.3271 1.200 1.85000 27.03 14) 23.5180 5.497 1.55332 71.68 15) -52.0328 D15 16) 41.1405 6.091 1.49782 82.57 17) -20.1879 1.200 1.90265 35.77 18) -73.5070 0.100 19) 34.8631 5.897 1.51742 52.20 20) -34.9935 D20 21) 172.2907 3.943 1.94594 17.98 22) -35.0000 1.200 1.95375 32.33 23) 26.3259 5.738 *24) -57.4239 1.200 1.85108 40.12 *25) -500.0000 D25 26) ∞ 6.005 1.49782 82.57 27) -39.4426 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 5.144E-07 1.164E-09 1.716E-12 -3.124E-15 2.173E-18 2) 0.0640 -3.203E-06 -1.109E-08 2.168E-11 -1.897E-13 3.095E-16 4) 0.8159 2.125E-05 2.707E-08 1.898E-10 -1.603E-13 1.291E-15 8) 1.0000 -2.462E-06 -4.251E-08 2.260E-10 -1.016E-12 3.328E-16 9) 1.0000 1.846E-06 -4.766E-08 3.216E-10 -1.819E-12 2.946E-15 24) 1.0000 -8.650E-05 6.147E-08 3.699E-09 -2.922E-11 7.296E-14 25) 1.0000 -4.710E-05 2.207E-07 2.446E-09 -1.884E-11 4.354E-14 [Focal length data for each group] Group First surface Focal length G1 1 -18.555 G2 8 52.351 G3 10 -296.108 G4 12 58.940 G5 16 31.288 G6 21 -21.926 G7 26 79.231 [Variable interval data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 13.469 9.679 1.500 15.292 11.363 2.743 D9 11.679 12.420 12.159 7.490 6.499 2.516 D11 5.872 3.772 3.120 8.239 8.009 11.521 D15 1.500 3.600 4.252 1.500 3.600 4.252 D20 1.532 1.500 2.383 1.532 1.500 2.383 D25 1.500 4.967 12.128 1.500 4.967 12.128 BF 11.243 10.857 11.253 11.243 10.857 11.253.

[0168] FIG. 4A is a diagram showing various aberrations of the variable magnification optical system of the second embodiment in the wide-angle end state, and FIG. 4B is a diagram showing various aberrations of the variable magnification optical system of the second embodiment in the telephoto end state.

[0169] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0170] (Third Example) Figure 5(a) is a cross-sectional view of the variable magnification optical system of the third example in the wide-angle end state, Figure 5(b) is a cross-sectional view of the variable magnification optical system of the third example in the intermediate focal length state, and Figure 5(c) is a cross-sectional view of the variable magnification optical system of the third example in the telephoto end state.

[0171] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 negative refractive power, and a seventh lens group G7 having positive refractive power.

[0172] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0173] The second lens group G2 is made up of a biconvex positive lens L5.

[0174] The third lens group G3 is made up of a negative meniscus lens L6 with its concave surface facing the object side.

[0175] The fourth lens group G4 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L7 with its convex surface facing the object side and a biconvex positive lens L8.

[0176] The fifth lens group G5 is composed of, in order from the object side, a cemented positive lens of a biconvex positive lens L9 and a meniscus negative lens L10 with its concave surface facing the object side, and a biconvex positive lens L11.

[0177] The sixth lens group G6 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L12 and a biconcave negative lens L13, and a meniscus negative lens L14 with its concave surface facing the object side.

[0178] The seventh lens group G7 is composed of a positive lens L15 having a plano-convex shape with its convex surface facing the image surface side.

[0179] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0180] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0181] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the third lens group G3 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the third lens group G3 corresponds to the second focusing lens group.

[0182] Table 3 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0183] (Table 3) [All elements] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.414 51.577 41.586 Y 21.700 21.700 21.700 TL 123.861 123.861 123.861 BF 10.607 10.607 10.607 [All elements] m r d n(d) νd * 1) 87.4925 2.500 1.61875 63.73 * 2) 16.6417 10.912 3) 75.7919 1.600 8) 39.7262 3.401 1.69343 53.30 9) -312.2227 D9 10) -44.9136 1.262 1.59319 67.90 11) -67.2463 D11 12) 53.1116 1.202 13) 39.7262 3.401 1.69343 53.30 14) -312.2227 D9 15) 53.1116 1.202 16) -44.9136 1.262 1.59319 67.90 16) -67.2463 D11 17) 53.1116 1.202 1.85000 27.03 14) 25.6476 5.344 1.55332 71.68 15) -47.4884 D15 16) 35.6725 6.479 1.49782 82.57 17) -20.0752 1.200 1.90265 35.77 18) -71.2076 0.101 19) 37.2763 5.883 1.51742 52.20 20) -33.9943 D20 21) 165.2927 3.984 1.94594 17.98 22) -35.0000 1.200 1.95375 32.33 23) 26.5861 5.984 *24) -55.8639 1.200 1.85108 40.12 *25) -500.0000 D25 26) ∞ 6.081 1.49782 82.57 27) -40.0524 BF [Aspheric surface] m K A4 A6 A8 A10 A12 1) 1.0000 4.647E-07 1.088E-09 1.746E-12 -3.110E-15 2.112E-18 2) 0.0615 -2.975E-06 -1.112E-08 1.854E-11 -1.886E-13 3.147E-16 4) 0.5655 2.214E-05 2.795E-08 1.967E-10 -2.054E-13 1.532E-15 8) 1.0000 -2.309E-06 -4.351E-08 2.402E-10 -9.583E-13 4.391E-16 9) 1.0000 1.970E-06 -4.919E-08 3.476E-10 -1.814E-12 3.065E-15 24) 1.0000 -8.686E-05 4.433E-08 3.883E-09 -3.071E-11 7.680E-14 25) 1.0000 -4.687E-05 2.192E-07 2.455E-09 -1.888E-11 4.366E-14 [Focus distance of each group] Focus distance from group starting plane G1 1 -18.558 G2 8 51.025 G3 10 -232.886 G4 12 62.875 G5 16 30.128 G6 21 -21.967 G7 26 80.456 [Changeable interval] When focusing at infinity When focusing at close range, corner end, middle telephoto end, corner end, middle telephoto end D7 13.020 9.143 1.500 14.724 10.752 2.936 D9 10.783 11.743 12.474 4.745 5.924 6.246 D11 6.536 4.067 2.260 10.870 8.278 7.052 D15 1.500 3.970 4.168 1.500 3.970 4.168 D20 1.500 1.521 2.290 1.500 1.521 2.290 D25 1.815 4.709 12.463 1.815 4.709 12.463 BF 10.607 10.607 10.607 10.607 10.607 10.607.

[0184] FIG. 6A is a diagram showing various aberrations of the variable magnification optical system of the third embodiment in the wide-angle end state, and FIG. 6B is a diagram showing various aberrations of the variable magnification optical system of the third embodiment in the telephoto end state.

[0185] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0186] (Fourth embodiment) Figure 7(a) is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the wide-angle end state, Figure 7(b) is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the intermediate focal length state, and Figure 7(c) is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the telephoto end state.

[0187] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative 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 positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.

[0188] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, and a negative meniscus lens L2 with a convex surface facing the object side.

[0189] The second lens group G2 is composed of, in order from the object side, a meniscus negative lens L3 with its convex surface facing the object side, and a cemented positive lens consisting of a biconcave negative lens L4 and a meniscus positive lens L5 with its convex surface facing the object side.

[0190] The third lens group G3 is made up of a biconvex positive lens L6.

[0191] The fourth lens group G4 is made up of a negative meniscus lens L7 with its convex surface facing the object side.

[0192] The fifth lens group G5 consists of, in order from the object side, an aperture stop S, a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9, a cemented positive lens consisting of a biconvex positive lens L10 and a meniscus negative lens L11 with its concave surface facing the object side, and a biconvex positive lens L12.

[0193] The sixth lens group G6 is composed of, in order from the object side, a cemented negative lens formed by a biconvex positive lens L13 and a biconcave negative lens L14, and a biconcave negative lens L15.

[0194] The seventh lens group G7 is composed of, in order from the object side, a biconvex positive lens L16 and a meniscus positive lens L17 with its concave surface facing the object side.

[0195] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0196] In the variable magnification optical system of this embodiment, the first lens group G1 and the second lens group G2 correspond to the front group, the first lens group G1 corresponds to the front first lens group, the third lens group G3 to the seventh lens group G7 correspond to the rear group, and the third lens group G3 corresponds to the rear first lens group.

[0197] The variable magnification optical system of this embodiment focuses by moving the third lens group G3 and the fourth lens group G4 along the optical axis. When focusing from infinity to a close-up object, the third lens group G3 and the fourth lens group G4 are each moved from the object side to the image plane side. The third lens group G3 corresponds to the first focusing lens group, and the fourth lens group G4 corresponds to the second focusing lens group.

[0198] Table 4 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0199] (Table 4) [Overall specifications] W M T f 13.390 17.000 23.280 FNo 2.912 2.912 2.914 ω 59.591 51.464 41.596 Y 21.700 21.700 21.700 TL 133.576 133.576 133.576 BF 10.492 10.255 12.538 [Lens specifications] m r d n(d) νd * 1) 197.4757 2.500 1.59255 67.86 * 2) 16.7947 10.498 3) 55.0000 1.600 1.77387 47.25 * 4) 37.3263 D4 5) 60.3936 1.500 1.61800 63.34 6) 24.4535 8.535 7) -63.0956 1.400 1.49782 82.57 8) 30.0253 5.580 1.85026 32.35 9) 849.8440 D9 *10) 31.7070 5.123 1.58286 59.50 *11) -85.4540 D11 12) 5833.2623 1.200 1.49782 82.57 13) 186.4964 D13 14> ∞ 0.200 (Aperture) 15) 42.6042 2.000 1.90265 35.77 16) 15.0000 6.989 1.55332 71.68 17) -98.2915 1.642 18) 50.2737 6.133 1.49782 82.57 19) -19.9003 1.200 1.90265 35.77 20) -41.8335 0.100 21) 47.3667 5.282 1.48749 70.32 22) -25.5675 D22 23) 107.2017 3.673 1.94594 17.98 24) -35.0000 1.200 2.00100 29.12 25) 26.1818 4.180 *26) -46.0822 1.200 1.85135 40.10 *27) 500.0000 D27 28) 275.4456 4.448 1.66382 27.35 29) -85.3689 0.100 30) -1196.4327 5.987 1.49782 82.57 31) -47.9131 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 3.274E-06 -3.404E-09 4.018E-12 -2.807E-15 8.986E-19 2) 0.1045 -8.173E-06 2.366E-09 1.673E-11 -1.607E-13 2.002E-16 4) 0.2000 1.658E-05 1.233E-09 5.718E-11 9.287E-14 -6.388E-17 10) 1.0000 -4.838E-06 -2.335E-08 5.957E-10 -4.659E-12 2.033E-14 11) 1.0000 3.217E-06 -6.370E-09 3.847E-10 -3.155E-12 1.736E-14 26) 1.0000 -7.734E-05 2.648E-07 1.467E-09 -2.678E-11 1.245E-13 27) 1.0000 -3.755E-05 3.873E-07 1.614E-10 -1.103E-11 4.646E-14 [Focal length data for each group] Group First surface Focal length G1 1 -24.247 G2 5 -87.616 G3 10 40.326 G4 12 -387.026 G5 14 24.789 G6 23 -19.046 G7 28 50.938 [Variable interval data] When focused at infinity When focusing at close distances Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D4 8.592 9.307 5.497 8.592 9.307 5.497 D9 14.292 7.087 1.500 15.502 8.808 3.244 D11 1.500 3.947 11.727 6.707 2.313 4.428 D13 12.020 9.573 1.793 5.603 9.486 7.347 D22 1.852 2.491 3.470 1.852 2.491 3.470 D27 2.558 8.647 14.782 2.558 8.647 14.782 BF 10.492 10.255 12.538 10.492 10.255 12.538.

[0200] FIG. 8A is a diagram showing various aberrations of the variable magnification optical system of the fourth embodiment in the wide-angle end state, and FIG. 8B is a diagram showing various aberrations of the variable magnification optical system of the fourth embodiment in the telephoto end state.

[0201] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0202] (Fifth Embodiment) Figure 9(a) is a cross-sectional view of the variable magnification optical system of the fifth embodiment in the wide-angle end state, Figure 9(b) is a cross-sectional view of the variable magnification optical system of the fifth embodiment in the intermediate focal length state, and Figure 9(c) is a cross-sectional view of the variable magnification optical system of the fifth embodiment in the telephoto end state.

[0203] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive 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 negative refractive power, and a seventh lens group G7 having negative refractive power.

[0204] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented positive lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0205] The second lens group G2 is made up of a biconvex positive lens L5.

[0206] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L6 with its convex surface facing the object side, and a negative meniscus lens L7 with its convex surface facing the object side.

[0207] The fourth lens group G4 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9.

[0208] The fifth lens group G5 consists of, in order from the object side, an aperture stop S, a meniscus negative lens L10 with its concave surface facing the object side, a cemented positive lens consisting of a biconvex positive lens L11 and a meniscus negative lens L12 with its concave surface facing the object side, and a biconvex positive lens L13.

[0209] The sixth lens group G6 is composed of a cemented negative lens made up of a biconvex positive lens L14 and a biconcave negative lens L15.

[0210] The seventh lens group G7 is made up of a negative meniscus lens L16 with its concave surface facing the object side.

[0211] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0212] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0213] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the sixth lens group G6 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the sixth lens group G6 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

[0214] Table 5 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0215] (Table 5) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.332 51.666 41.574 Y 21.700 21.700 21.700 TL 132.555 132.555 132.555 BF 17.650 20.795 27.606 [Lens specifications] m r d n(d) νd * 1) 188.7367 5.900 1.61875 63.73 * 2) 16.0000 12.714 3) 69.9934 2.700 1.82098 42.50 * 4) 32.4768 7.653 5) -108.1566 1.400 1.49782 82.57 6) 25.5003 6.984 1.85026 32.35 7) 96.3197 D7 * 8) 72.2215 3.706 1.61875 63.73 * 9) -67.6908 D9 10) 27.6733 3.639 1.59270 35.27 11) 430.1407 0.189 12) 2340.9838 1.200 1.90265 35.77 13) 45.9519 D13 14> ∞ 1.082 (Aperture) 15) 66.0645 1.200 1.90265 35.77 16) 23.2119 5.616 1.55332 71.68 17) -38.0912 D17 18) -34.3583 1.200 1.80610 33.35 19) -200.0000 0.100 20) 29.6936 7.138 1.49782 82.57 21) -19.0143 1.200 1.83481 42.73 22) -35.4593 0.100 23) 34.3086 5.609 1.49782 82.57 24) -45.4690 D24 25) 387.5346 3.535 1.94594 17.98 26) -40.8696 1.200 1.90265 35.77 27) 40.4117 D27 *28) -101.5816 1.500 1.85135 40.10 *29) -500.0000 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 4.147E-06 -5.254E-09 4.756E-12 -2.084E-15 3.931E-19 2) 0.2647 1.756E-06 1.594E-08 2.052E-12 -1.654E-13 3.150E-16 4) 0.1879 1.314E-05 -9.139E-09 1.659E-10 -4.220E-13 9.045E-16 8) -4.9528 -1.968E-06 -8.306E-09 3.309E-11 7.305E-14 3.307E-15 9) 3.0481 -4.228E-07 9.335E-10 -7.211E-11 8.619E-13 1.073E-15 28) 1.0000 -1.514E-04 -8.606E-08 5.905E-09 -1.835E-11 -4.882E-15 29) 1.0000 -1.113E-04 1.450E-07 4.999E-09 -2.118E-11 2.425E-14 [Focal length data for each group] Group First surface Focal length G1 1 -18.112 G2 8 57.049 G3 10 471.937 G4 14 75.699 G5 18 33.640 G6 25 -53.497 G7 28 -150.000 [Variable distance data] When focused at infinity When focused at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 15.702 9.989 1.500 18.207 12.693 4.466 D9 4.054 8.917 6.879 1.549 6.213 3.913 D13 10.066 5.022 2.984 10.066 5.022 2.984 D17 1.647 4.396 10.151 1.647 4.396 10.151 D24 1.810 1.961 3.265 1.507 1.509 2.536 D27 6.061 5.910 4.605 6.364 6.362 5.335 BF 17.650 20.795 27.606 17.650 20.795 27.606.

[0216] FIG. 10A is a diagram showing various aberrations of the variable magnification optical system of the fifth embodiment in the wide-angle end state, and FIG. 10B is a diagram showing various aberrations of the variable magnification optical system of the fifth embodiment in the telephoto end state.

[0217] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0218] (Sixth Embodiment) Figure 11(a) is a cross-sectional view of the variable magnification optical system of the sixth embodiment in the wide-angle end state, Figure 11(b) is a cross-sectional view of the variable magnification optical system of the sixth embodiment in the intermediate focal length state, and Figure 11(c) is a cross-sectional view of the variable magnification optical system of the sixth embodiment in the telephoto end state.

[0219] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 negative refractive power, and a seventh lens group G7 having negative refractive power.

[0220] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0221] The second lens group G2 is made up of a biconvex positive lens L5.

[0222] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L6 with a convex surface facing the object side, and a negative meniscus lens L7 with a concave surface facing the object side.

[0223] The fourth lens group G4 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9.

[0224] The fifth lens group G5 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L10 and a biconcave negative lens L11, and a biconvex positive lens L12.

[0225] The sixth lens group G6 is composed of a cemented negative lens made up of a meniscus positive lens L13 with its concave surface facing the object side and a biconcave negative lens L14.

[0226] The seventh lens group G7 is composed of, in order from the object side, a negative meniscus lens L15 with its concave surface facing the object side, and a positive biconvex lens L16.

[0227] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0228] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0229] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the sixth lens group G6 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the image plane side to the object side, and the sixth lens group G6 is moved from the object side to the image plane side. The second lens group G2 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

[0230] Table 6 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0231] (Table 6) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.210 51.156 41.570 Y 21.700 21.700 21.700 TL 125.655 125.655 125.655 BF 10.255 12.654 19.943 [Lens specifications] m r d n(d) νd * 1) 129.0679 5.900 1.61875 63.73 * 2) 16.9121 10.662 3) 69.9357 2.700 1.82098 42.50 * 4) 31.7080 9.316 5) -65.4001 1.400 1.49782 82.57 6) 23.2380 7.403 1.85026 32.35 7) 82.9442 D7 * 8) 76.8222 3.439 1.69343 53.30 * 9) -59.5270 D9 10) 30.3657 2.076 1.73800 32.33 11) 42.3894 3.375 12) -42.3142 1.200 1.90366 31.27 13) -86.8101 D13 14> ∞ 0.958 (Aperture) 15) 51.9855 1.200 1.95000 29.37 16) 22.6614 5.919 1.55332 71.68 17) -32.6224 D17 18) 34.4159 5.648 1.49782 82.57 19) -21.7261 1.200 1.83481 42.73 20) 1631.7122 0.100 21) 34.8798 5.800 1.51823 58.82 22) -30.6920 D22 23) -1595.8381 3.387 1.94594 17.98 24) -35.0000 1.200 1.90265 35.77 25) 32.6943 D25 *26) -71.7042 1.500 1.85135 40.10 *27) -500.0000 1.687 28) 497.1333 4.075 1.49782 82.57 29) -58.4720 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 2.874E-06 -3.037E-09 3.837E-12 -2.429E-15 7.902E-19 2) 0.0548 -1.159E-06 -1.168E-09 -7.614E-12 -1.808E-13 3.235E-16 4) 0.6660 2.277E-05 1.957E-08 2.227E-10 -3.104E-13 1.842E-15 8) 1.0000 -2.528E-06 -2.376E-08 2.828E-10 -2.360E-12 1.467E-14 9) 1.0000 -3.612E-07 -1.461E-08 1.362E-10 -9.504E-13 1.013E-14 26) 1.0000 -1.524E-04 -3.804E-08 5.744E-09 -2.464E-11 2.624E-14 27) 1.0000 -1.155E-04 2.403E-07 3.840E-09 -1.897E-11 2.801E-14 [Focal length data for each group] Group First surface Focal length G1 1 -17.728 G2 8 48.871 G3 10 -348.184 G4 14 56.578 G5 18 35.123 G6 23 -37.064 G7 26 -5784.663 [Variable distance data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 14.666 10.578 1.500 14.538 12.640 3.937 D9 2.336 3.859 6.254 2.464 1.798 3.817 D13 7.786 4.853 1.500 7.786 4.853 1.500 D17 1.500 4.433 7.786 1.500 4.433 7.786 D22 1.973 1.658 3.553 2.762 1.501 3.111 D25 6.994 7.474 4.974 6.206 7.632 5.416 BF 10.255 12.654 19.943 10.255 12.654 19.943.

[0232] FIG. 12A is a diagram showing various aberrations of the variable magnification optical system of the sixth embodiment in the wide-angle end state, and FIG. 12B is a diagram showing various aberrations of the variable magnification optical system of the sixth embodiment in the telephoto end state.

[0233] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0234] (Seventh Example) Figure 13(a) is a cross-sectional view of the variable magnification optical system of the seventh example in the wide-angle end state, Figure 13(b) is a cross-sectional view of the variable magnification optical system of the seventh example in the intermediate focal length state, and Figure 13(c) is a cross-sectional view of the variable magnification optical system of the seventh example in the telephoto end state.

[0235] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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, a seventh lens group G7 having negative refractive power, and an eighth lens group G8 having positive refractive power.

[0236] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0237] The second lens group G2 is made up of a biconvex positive lens L5.

[0238] The third lens group G3 is composed of, in order from the object side, a meniscus-shaped positive lens L6 with its convex surface facing the object side, and a biconcave negative lens L7.

[0239] The fourth lens group G4 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9.

[0240] The fifth lens group G5 is composed of a cemented negative lens consisting of a biconvex positive lens L10 and a meniscus negative lens L11 with its concave surface facing the object side.

[0241] The sixth lens group G6 is made up of a biconvex positive lens L12.

[0242] The seventh lens group G7 is composed of a cemented negative lens made up of a biconvex positive lens L13 and a biconcave negative lens L14.

[0243] The eighth lens group G8 is composed of, in order from the object side, a negative meniscus lens L15 with its concave surface facing the object side, and a positive biconvex lens L16.

[0244] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0245] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the eighth lens group G8 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0246] The variable magnification optical system of this embodiment focuses by moving the sixth lens group G6 and the seventh lens group G7 along the optical axis. When focusing from infinity to a close-up object, the sixth lens group G6 is moved from the image plane side to the object side, and the seventh lens group G7 is moved from the object side to the image plane side. The sixth lens group G6 corresponds to the first focusing lens group, and the seventh lens group G7 corresponds to the second focusing lens group.

[0247] Table 7 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0248] (Table 7) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.537 51.864 41.583 Y 21.700 21.700 21.700 TL 135.555 135.555 135.555 BF 10.255 13.213 19.083 [Lens specifications] m r d n(d) νd * 1) 172.3513 5.900 1.61875 63.73 * 2) 16.3268 12.099 3) 69.9808 2.700 1.82098 42.50 * 4) 32.8290 9.016 5) -64.2024 1.400 1.49782 82.57 6) 27.4983 6.065 1.85026 32.35 7) 138.2613 D7 * 8) 38.7816 3.874 1.69343 53.30 * 9) -97.8439 D9 10) 47.2824 2.054 1.73800 32.33 11) 93.0701 2.962 12) -62.7273 1.500 1.90265 35.77 13) 1914.5872 D13 14> ∞ 0.912 (Aperture) 15) 48.1442 1.200 1.95375 32.33 16) 19.2337 5.842 1.55332 71.68 17) -37.5924 D17 18) 124.9905 4.929 1.49782 82.57 19) -19.0000 1.200 1.83481 42.73 20) -244.1682 D20 *21) 44.3609 7.631 1.59255 67.86 *22) -27.6980 D22 23) 152.6414 4.020 1.94594 17.98 24) -51.4514 1.200 1.90366 31.27 25) 38.4221 D25 *26) -93.6585 1.200 1.85135 40.10 *27) -500.0000 3.292 28) 494.6657 3.988 1.49782 82.57 29) -75.4802 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 4.575E-06 -5.592E-09 4.800E-12 -2.063E-15 3.929E-19 2) 0.1614 6.514E-07 1.959E-08 -3.261E-11 -2.059E-13 3.068E-16 4) 0.9347 1.419E-05 -9.234E-09 2.415E-10 -4.502E-13 1.020E-15 8) 1.0000 -3.235E-06 8.263E-09 -1.476E-11 -1.650E-13 2.270E-15 9) 1.0000 -1.398E-06 1.232E-08 -6.157E-11 1.590E-13 1.342E-15 21) 1.0000 -5.686E-06 1.437E-08 -1.339E-10 7.194E-13 -2.658E-16 22) 1.0000 2.552E-06 -4.459E-09 1.162E-10 -7.671E-13 3.285E-15 26) 1.0000 -8.513E-05 -2.302E-07 5.749E-09 -2.490E-11 3.853E-14 27) 1.0000 -6.914E-05 -6.968E-08 4.149E-09 -1.801E-11 2.689E-14 [Each group focal length data] Group First plane Focal length G1 1 -18.020 G2 8 40.523 G3 10 -155.766 G4 14 72.328 G5 18 -98.848 G6 21 29.957 G7 23 -62.090 G8 26 1769.028 [Variable Interval Data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 18.964 12.868 1.500 18.964 12.868 1.500 D9 2.998 4.922 7.794 2.998 4.922 7.794 D13 6.817 4.893 2.021 6.817 4.893 2.021 D17 1.500 3.424 6.296 1.500 3.424 6.296 D20 1.604 3.067 3.172 1.432 3.095 1.515 D22 1.667 2.631 6.774 2.796 4.384 8.079 D25 8.767 7.553 5.932 7.809 5.772 6.284 BF 10.255 13.213 19.083 10.255 13.213 19.083.

[0249] FIG. 14A is a diagram showing various aberrations of the variable magnification optical system of the seventh embodiment in the wide-angle end state, and FIG. 14B is a diagram showing various aberrations of the variable magnification optical system of the seventh embodiment in the telephoto end state.

[0250] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0251] (Eighth Embodiment) Figure 15(a) is a cross-sectional view of the variable magnification optical system of the eighth embodiment in the wide-angle end state, Figure 15(b) is a cross-sectional view of the variable magnification optical system of the eighth embodiment in the intermediate focal length state, and Figure 15(c) is a cross-sectional view of the variable magnification optical system of the eighth embodiment in the telephoto end state.

[0252] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 negative refractive power, and a seventh lens group G7 having negative refractive power.

[0253] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0254] The second lens group G2 is made up of a biconvex positive lens L5.

[0255] The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L6 with a convex surface facing the object side, and a negative meniscus lens L7 with a concave surface facing the object side.

[0256] The fourth lens group G4 is composed of, in order from the object side, an aperture stop S, and a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9.

[0257] The fifth lens group G5 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L10 and a biconcave negative lens L11, and a biconvex positive lens L12.

[0258] The sixth lens group G6 is composed of a cemented negative lens made up of a meniscus positive lens L13 with its concave surface facing the object side and a biconcave negative lens L14.

[0259] The seventh lens group G7 is composed of, in order from the object side, a negative meniscus lens L15 with its concave surface facing the object side, and a positive biconvex lens L16.

[0260] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0261] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0262] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side.

[0263] Table 8 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0264] (Table 8) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.144 51.090 41.571 Y 21.700 21.700 21.700 TL 125.655 125.655 125.655 BF 10.255 12.868 20.525 [Lens specifications] m r d n(d) νd * 1) 143.2118 5.900 1.61875 63.73 * 2) 16.2491 10.438 3) 69.8008 2.700 1.82098 42.50 * 4) 33.1541 8.804 5) -66.7388 1.400 1.49782 82.57 6) 22.9654 7.510 1.85026 32.35 7) 84.5858 D7 * 8) 78.4716 3.419 1.69343 53.30 * 9) -59.5907 D9 10) 30.4263 2.254 1.73800 32.33 11) 48.9835 2.427 12) -49.0904 1.200 1.90366 31.27 13) -198.8181 D13 14> ∞ 0.941 (Aperture) 15) 50.6580 1.200 1.95000 29.37 16) 22.3330 5.916 1.55332 71.68 17) -32.8805 D17 18) 33.5027 5.580 1.49782 82.57 19) -22.3758 1.200 1.83481 42.73 20) 319.6889 0.100 21) 32.4667 5.823 1.51823 58.82 22) -31.3864 D22 23) -2356.1002 3.371 1.94594 17.98 24) -35.0000 1.200 1.90265 35.77 25) 35.3920 D25 *26) -67.7223 1.500 1.85135 40.10 *27) -500.0000 1.686 28) 495.4430 4.093 1.49782 82.57 29) -57.8164 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 2.569E-06 -2.805E-09 3.795E-12 -2.462E-15 7.780E-19 2) 0.0309 -1.701E-06 -2.019E-09 -1.738E-11 -1.720E-13 3.440E-16 4) 0.6885 2.309E-05 1.836E-08 2.502E-10 -4.558E-13 2.142E-15 8) 1.0000 -1.002E-06 -2.791E-08 3.024E-10 -2.611E-12 1.588E-14 9) 1.0000 3.142E-07 -1.824E-08 1.551E-10 -1.197E-12 1.143E-14 26) 1.0000 -1.522E-04 4.410E-08 5.493E-09 -2.603E-11 2.941E-14 27) 1.0000 -1.129E-04 3.099E-07 3.594E-09 -2.000E-11 3.202E-14 [Focal length data for each group] Group First surface Focal length G1 1 -17.808 G2 8 49.345 G3 10 -292.685 G4 14 56.327 G5 18 35.719 G6 23 -40.531 G7 26 -1367.735 [Variable distance data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 14.694 10.663 1.500 16.454 12.421 3.344 D9 3.273 4.707 7.119 1.513 2.949 5.275 D13 7.874 4.858 1.500 7.874 4.858 1.500 D17 1.500 4.516 7.874 1.500 4.516 7.874 D22 1.846 1.500 3.622 1.846 1.500 3.622 D25 7.551 7.881 4.853 7.551 7.881 4.853 BF 10.255 12.868 20.525 10.255 12.868 20.525.

[0265] FIG. 16A is a diagram showing various aberrations of the variable magnification optical system of the eighth embodiment in the wide-angle end state, and FIG. 16B is a diagram showing various aberrations of the variable magnification optical system of the eighth embodiment in the telephoto end state.

[0266] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0267] (Ninth Example) Figure 17(a) is a cross-sectional view of the variable magnification optical system of the ninth example in the wide-angle end state, Figure 17(b) is a cross-sectional view of the variable magnification optical system of the ninth example in the intermediate focal length state, and Figure 17(c) is a cross-sectional view of the variable magnification optical system of the ninth example in the telephoto end state.

[0268] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power.

[0269] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0270] The second lens group G2 consists of, in order from the object side, a meniscus positive lens L5 with its convex surface facing the object side, an aperture stop S, a cemented positive lens formed by a meniscus negative lens L6 with its convex surface facing the object side and a biconvex positive lens L7, a cemented negative lens formed by a biconvex positive lens L8 and a biconcave negative lens L9, and a biconvex positive lens L10.

[0271] The third lens group G3 is composed of a cemented negative lens made up of a meniscus positive lens L11 with its concave surface facing the object side and a biconcave negative lens L12.

[0272] The fourth lens group G4 is made up of a negative meniscus lens L13 with its concave surface facing the object side.

[0273] The fifth lens group G5 is made up of a biconvex positive lens L14.

[0274] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0275] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the fifth lens group G5 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0276] The variable magnification optical system of this embodiment focuses by moving the third lens group G3 and the fourth lens group G4 along the optical axis. When focusing on a close object from a state focused on infinity, the third lens group G3 and the fourth lens group G4 are each moved from the object side to the image plane side. The third lens group G3 corresponds to the first focusing lens group, and the fourth lens group G4 corresponds to the second focusing lens group.

[0277] Table 9 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0278] (Table 9) [Overall specifications] W M T f 14.500 18.001 23.062 FNo 2.912 2.912 2.912 ω 58.632 51.464 42.686 Y 21.700 21.700 21.700 TL 108.050 108.050 108.050 BF 12.640 13.775 16.381 [Lens specifications] m r d n(d) νd * 1) 71.6742 5.000 1.59255 67.86 * 2) 16.0000 13.000 3) 113.7322 3.000 1.58887 61.13 * 4) 31.5953 7.402 5) -600.2560 1.200 1.49782 82.57 6) 16.5452 4.731 1.69895 30.13 7) 36.3843 D7 * 8) 16.7697 3.772 1.58887 61.13 * 9) 39.3181 4.450 10> ∞ 4.165 (Aperture stop) 11) 39.5808 2.266 1.59270 35.27 12) 34.2914 3.582 1.49782 82.57 13) -40.0000 1.046 14) 76.6779 4.865 1.49782 82.57 15) -12.7777 1.200 1.59270 35.27 16) 247.7007 0.100 17) 30.4930 3.454 1.49782 82.57 18) -36.4639 D18 19) -84.5243 3.542 1.94594 17.98 20) -16.2052 1.000 1.84666 23.80 21) 99.1299 D21 22) -22.8170 1.000 1.85135 40.10 *23) -133.6556 D23 24) 67.0493 6.595 1.59270 35.27 25) -48.0817 BF [Aspherical data] m K A4 A6 A8 A10 A12 1) 2.1015 4.901E-06 -1.838E-08 2.745E-11 -1.966E-14 5.852E-18 2) -0.5313 2.923E-05 -1.079E-08 -2.484E-10 3.617E-13 -5.707E-17 4) 0.7652 2.737E-05 -1.591E-09 1.195E-09 -5.575E-12 2.005E-14 8) 1.0000 2.390E-05 1.781E-07 2.549E-09 -2.451E-11 3.562E-13 9) 1.0000 6.336E-05 2.915E-07 4.199E-09 -5.642E-11 8.539E-13 23) 1.0000 4.581E-05 1.714E-08 2.546E-10 -3.960E-12 1.341E-14 [Focal length data for each group] Group First surface Focal length G1 1 -16.191 G2 8 20.688 G3 19 -73.112 G4 22 -32.453 G5 24 48.273 [Variable interval data] When focused at infinity When focusing at close distances Wide-angle Mid-range Telephoto Wide-angle Mid-range Telephoto D7 12.301 7.289 1.500 12.301 7.289 1.500 D18 1.500 1.819 2.923 1.953 3.024 5.134 D21 3.887 4.969 6.619 3.928 3.821 3.972 D23 2.353 4.794 5.210 1.859 4.736 5.646 BF 12.640 13.775 16.381 12.640 13.775 16.381

[0279] FIG. 18A is a diagram showing various aberrations of the variable magnification optical system of the ninth embodiment in the wide-angle end state, and FIG. 18B is a diagram showing various aberrations of the variable magnification optical system of the ninth embodiment in the telephoto end state.

[0280] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0281] (10th Example) Figure 19(a) is a cross-sectional view of the variable magnification optical system of the 10th example in the wide-angle end state, Figure 19(b) is a cross-sectional view of the variable magnification optical system of the 10th example in the intermediate focal length state, and Figure 19(c) is a cross-sectional view of the variable magnification optical system of the 10th example in the telephoto end state.

[0282] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 negative refractive power, and a seventh lens group G7 having positive refractive power.

[0283] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0284] The second lens group G2 is made up of a positive meniscus lens L5 with its convex surface facing the object side.

[0285] The third lens group G3 is made up of a negative meniscus lens L6 with its concave surface facing the object side.

[0286] The fourth lens group G4 consists of, in order from the object side, a meniscus positive lens L7 with its convex surface facing the object side, a biconvex positive lens L8, an aperture stop S, and a cemented negative lens consisting of a meniscus negative lens L9 with its convex surface facing the object side and a biconvex positive lens L10.

[0287] The fifth lens group G5 is composed of, in order from the object side, a meniscus positive lens L11 with its convex surface facing the object side, and a biconvex positive lens L12.

[0288] The sixth lens group G6 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L13 and a biconcave negative lens L14, and a meniscus negative lens L15 with its concave surface facing the object side.

[0289] The seventh lens group G7 is composed of a positive meniscus lens L16 with its concave surface facing the object side.

[0290] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0291] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0292] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the third lens group G3 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the third lens group G3 corresponds to the second focusing lens group.

[0293] Table 10 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0294] (Table 10) [Overall specifications] W M T f 14.420 17.000 33.950 FNo 2.912 2.912 2.912 ω 58.355 52.072 30.422 Y 21.700 21.700 21.700 TL 139.555 139.555 139.555 BF 12.855 13.477 17.661 [Lens specifications] m r d n(d) νd * 1) 58.9173 3.810 1.59255 67.86 * 2) 17.9520 13.206 3) 63.5511 1.600 1.77387 47.25 * 4) 39.0467 10.046 5) -95.9750 1.400 1.49782 82.57 6) 24.8039 5.101 1.85000 27.03 7) 41.9836 D7 8) 42.1300 3.557 1.72047 34.71 9) 203.7336 D9 10) -43.0320 1.200 1.49782 82.57 11) -445.6673 D11 *12) 25.2161 4.148 1.58286 59.50 *13) 51.5856 1.569 14) 37.5496 5.712 1.49782 82.57 15) -100.4213 1.189 16> ∞ 0.260 (Aperture) 17) 71.1133 1.200 2.00100 29.12 18) 18.3265 7.700 1.55332 71.68 19) -352.5331 D19 20) 33.2666 3.972 1.49782 82.57 21) 210.2966 0.100 22) 28.1523 4.843 1.51823 58.82 23) -107.7398 D23 24) 62.8334 4.451 1.94594 17.98 25) -35.0000 1.200 2.00100 29.12 26) 22.3132 3.901 *27) -64.9221 1.200 1.85135 40.10 *28) -758.8231 D28 29) -59.0274 5.796 1.49782 82.57 *30) -24.3623 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 -2.034E-06 -2.937E-09 6.271E-12 -4.203E-15 1.124E-18 2) 0.0556 4.831E-06 -3.685E-09 -3.221E-11 -1.481E-14 5.915E-17 4) 1.0000 5.617E-06 8.492E-09 8.576E-11 -1.533E-13 3.787E-16 12) 1.0000 -1.180E-06 -6.042E-10 1.701E-11 -2.855E-13 13) 1.0000 1.184E-05 6.435E-09 7.622E-12 -3.057E-13 27) 1.0000 -1.132E-04 1.156E-06 -2.616E-09 -3.179E-12 28) 1.0000 -7.869E-05 1.183E-06 -3.130E-09 1.008E-12 30) 1.0000 1.563E-05 -6.153E-09 -4.437E-12 2.188E-14 [Focal length data for each group] Group First surface Focal length G1 1 -19.578 G2 8 73.047 G3 10 -95.774 G4 12 44.877 G5 20 28.991 G6 24 -23.673 G7 29 78.944 [Variable distance data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end 1.511 21.703 13.694 1.706 D9 5.552 9.180 6.803 2.941 6.007 2.954 D11 9.086 7.344 1.500 9.689 9.694 5.155 D19 1.000 3.136 1.000 1.000 3.136 1.000 D23 1.500 2.565 5.062 1.500 2.565 5.062 D28 2.706 3.820 18.856 2.706 3.820 18.856 BF 12.855 13.477 17.661 12.855 13.477 17.661.

[0295] FIG. 20A is a diagram showing various aberrations of the variable magnification optical system of the tenth embodiment in the wide-angle end state, and FIG. 20B is a diagram showing various aberrations of the variable magnification optical system of the tenth embodiment in the telephoto end state.

[0296] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0297] (Eleventh Embodiment) Figure 21(a) is a cross-sectional view of the variable magnification optical system of the eleventh embodiment in the wide-angle end state, Figure 21(b) is a cross-sectional view of the variable magnification optical system of the eleventh embodiment in the intermediate focal length state, and Figure 21(c) is a cross-sectional view of the variable magnification optical system of the eleventh embodiment in the telephoto end state.

[0298] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative 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 positive refractive power, a sixth lens group G6 having negative refractive power, and a seventh lens group G7 having positive refractive power.

[0299] The first lens group G1 is composed of, in order from the object side, a negative meniscus lens L1 with a convex surface facing the object side, and a negative meniscus lens L2 with a convex surface facing the object side.

[0300] The second lens group G2 is composed of, in order from the object side, a negative meniscus lens L3 with a convex surface facing the object side, a negative biconcave lens L4, and a positive meniscus lens L5 with a convex surface facing the object side.

[0301] The third lens group G3 is made up of a biconvex positive lens L6.

[0302] The fourth lens group G4 is made up of a biconcave negative lens L7.

[0303] The fifth lens group G5 consists of, in order from the object side, a meniscus positive lens L8 with its convex surface facing the object side, an aperture stop S, a cemented positive lens consisting of a meniscus negative lens L9 with its convex surface facing the object side and a biconvex positive lens L10, a cemented positive lens consisting of a biconvex positive lens L11 and a meniscus negative lens L12 with its concave surface facing the object side, and a biconvex positive lens L13.

[0304] The sixth lens group G6 is composed of, in order from the object side, a cemented negative lens formed by a biconvex positive lens L14 and a biconcave negative lens L15, and a biconcave negative lens L16.

[0305] The seventh lens group G7 is made up of a biconcave negative lens L17.

[0306] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0307] In the variable magnification optical system of this embodiment, the first lens group G1 to the second lens group G2 correspond to the front group, the first lens group G1 corresponds to the front first lens group, the third lens group G3 to the seventh lens group G7 correspond to the rear group, and the third lens group G3 corresponds to the rear first lens group.

[0308] The variable magnification optical system of this embodiment focuses by moving the third lens group G3 and the fourth lens group G4 along the optical axis. When focusing on a close object from a state focused on infinity, the third lens group G3 and the fourth lens group G4 are each moved from the object side to the image plane side. The third lens group G3 corresponds to the first focusing lens group, and the fourth lens group G4 corresponds to the second focusing lens group.

[0309] Table 11 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0310] (Table 11) [Overall specifications] W M T f 13.390 17.000 23.280 FNo 2.912 2.912 2.912 ω 59.198 51.384 41.592 Y 21.700 21.700 21.700 TL 128.918 128.918 128.918 BF 13.438 13.588 17.012 [Lens specifications] m r d n(d) νd * 1) 200.0000 2.500 1.59255 67.86 * 2) 17.3158 10.338 3) 55.0000 1.600 1.77387 47.25 * 4) 36.6305 D4 5) 81.2844 1.500 1.61800 63.34 6) 29.4316 7.110 7) -77.2913 1.400 1.49782 82.57 8) 26.8166 0.224 9) 27.6836 5.692 1.85026 32.35 10) 381.9072 D10 *11) 38.5869 4.298 1.58286 59.50 *12) -102.1608 D12 13) -54.6772 1.200 1.49782 82.57 14) 217.7759 D14 15) 27.0266 3.843 1.48749 70.32 16) 174.2117 3.590 17> ∞ 1.000 (Aperture stop) 18) 43.2458 1.787 1.90265 35.77 19) 15.0000 6.489 1.55332 71.68 20) -172.3234 0.100 21) 40.1648 5.936 1.49782 82.57 22) -21.3107 1.200 1.90265 35.77 23) -66.5261 0.100 24) 30.9552 5.337 1.48749 70.32 25) -29.5641 D25 26) 68.0645 3.774 1.94594 17.98 27) -35.0000 1.200 2.00100 29.12 28) 25.2466 4.051 *29) -37.8108 1.200 1.85135 40.10 *30) 500.0000 D30 31) -203.8201 6.342 1.70000 48.10 32) -31.4460 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 3.883E-06 -3.603E-09 4.145E-12 -2.746E-15 8.781E-19 2) 0.1512 -8.427E-06 4.651E-09 8.180E-12 -1.454E-13 1.935E-16 4) 0.8928 1.671E-05 7.561E-10 9.756E-11 -2.641E-14 2.665E-16 11) 1.0000 -9.533E-07 -1.685E-08 1.195E-09 -9.307E-12 4.913E-14 12) 1.0000 3.315E-06 3.830E-09 1.013E-09 -8.431E-12 5.259E-14 29) 1.0000 -7.027E-05 2.635E-07 -5.269E-10 -4.949E-12 4.577E-14 30) 1.0000 -1.263E-05 3.562E-07 -4.270E-10 -5.526E-12 2.641E-14 [Focal length data for each group] Group Initial surface Focal length G1 1 -24.613 G2 5 -110.408 G3 11 48.599 G4 13 -87.663 G5 15 23.629 G6 26 -19.267 G7 31 52.325 [Variable spacing data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D4 9.619 9.960 5.808 9.619 9.960 5.808 D10 12.994 6.616 1.500 15.473 8.402 3.155 D12 2.842 3.998 5.661 3.537 1.944 3.115 D14 4.622 3.467 1.803 1.449 3.735 2.695 D25 1.500 1.852 2.620 1.500 1.852 2.620 D30 2.090 7.624 12.701 2.090 7.624 12.701 BF 13.438 13.588 17.012 13.438 13.588 17.012.

[0311] FIG. 22(a) is a diagram showing various aberrations of the variable magnification optical system of Example 11 in the wide-angle end state, and FIG. 22(b) is a diagram showing various aberrations of the variable magnification optical system of Example 11 in the telephoto end state.

[0312] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0313] (Twelfth Embodiment) Figure 23(a) is a cross-sectional view of the variable magnification optical system of the twelfth embodiment in the wide-angle end state, Figure 23(b) is a cross-sectional view of the variable magnification optical system of the twelfth embodiment in the intermediate focal length state, and Figure 23(c) is a cross-sectional view of the variable magnification optical system of the twelfth embodiment in the telephoto end state.

[0314] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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.

[0315] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented positive lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0316] The second lens group G2 is made up of a positive meniscus lens L5 with its convex surface facing the object side.

[0317] The third lens group G3 is made up of a biconcave negative lens L6.

[0318] The fourth lens group G4 consists of, in order from the object side, a biconvex positive lens L7, an aperture stop S, a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9, a cemented negative lens consisting of a biconvex positive lens L10 and a meniscus negative lens L11 with its concave surface facing the object side, and a biconvex positive lens L12.

[0319] The fifth lens group G5 is composed of, in order from the object side, a cemented negative lens of a biconvex positive lens L13 and a biconcave negative lens L14, and a biconcave negative lens L15.

[0320] The sixth lens group G6 is composed of a positive meniscus lens L16 with its concave surface facing the object side.

[0321] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0322] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the sixth lens group G6 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0323] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the third lens group G3 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the third lens group G3 corresponds to the second focusing lens group.

[0324] Table 12 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0325] (Table 12) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.912 ω 57.571 51.943 41.584 Y 21.700 21.700 21.700 TL 124.493 124.492 124.493 BF 14.045 12.444 12.244 [Lens specifications] m r d n(d) νd * 1) 91.2098 2.500 1.59255 67.86 * 2) 17.3506 12.166 3) 107.2250 1.600 1.77387 47.25 * 4) 29.3532 8.633 5) -65.2307 1.400 1.49782 82.57 6) 26.3178 6.383 1.85000 27.03 7) 153.1744 D7 * 8) 29.2616 3.417 1.58286 59.50 * 9) 133.7667 D9 10) -40.1832 1.200 1.49782 82.57 11) 371.4491 D11 12) 25.9179 5.083 1.48749 70.32 13) -110.6127 1.203 14> ∞ 0.200 (Aperture) 15) 44.2701 1.200 1.90265 35.77 16) 17.1295 6.053 1.55332 71.68 17) -139.9702 0.100 18) 48.5249 6.158 1.49782 82.57 19) -19.0000 1.200 1.90265 35.77 20) -129.4277 0.531 21) 31.6813 4.448 1.51823 58.82 22) -49.3823 D22 23) 51.5367 4.298 1.94594 17.98 24) -35.0000 1.200 1.85000 27.03 25) 24.6534 3.918 *26) -56.8118 1.200 1.85135 40.10 *27) 500.0000 D27 28) -244.1439 5.470 1.49782 82.57 29) -36.6244 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 3.074E-06 -2.198E-09 4.115E-12 -2.758E-15 1.391E-18 2) 0.0619 1.636E-06 -4.180E-09 3.709E-11 -2.045E-13 2.978E-16 4) 0.5897 2.078E-05 2.326E-08 1.237E-10 4.825E-14 4.101E-16 8) 1.0000 5.919E-06 -1.695E-08 1.116E-09 -7.047E-12 3.879E-14 9) 1.0000 1.117E-05 8.910E-09 6.729E-10 -2.240E-12 2.402E-14 26) 1.0000 -5.678E-05 2.354E-07 1.815E-10 4.635E-12 -6.984E-14 27) 1.0000 -8.029E-06 3.050E-07 8.768E-10 -8.046E-12 1.900E-16 [Focal length data for each group] Group First surface Focal length G1 1 -18.870 G2 8 63.496 G3 10 -72.768 G4 12 24.548 G5 23 -35.462 G6 28 85.802 [Variable distance data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 16.149 12.087 1.864 17.368 12.980 1.963 D9 5.374 6.018 6.580 3.180 3.731 4.059 D11 3.659 3.172 4.432 4.634 4.566 6.854 D22 3.573 4.074 6.371 3.573 4.074 6.371 D27 2.131 7.136 13.440 2.131 7.136 13.440 BF 14.045 12.444 12.244 14.045 12.444 12.244.

[0326] FIG. 24A is a diagram showing various aberrations of the variable magnification optical system of the twelfth embodiment in the wide-angle end state, and FIG. 24B is a diagram showing various aberrations of the variable magnification optical system of the twelfth embodiment in the telephoto end state.

[0327] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0328] (13th Embodiment) Figure 25(a) is a cross-sectional view of the variable magnification optical system of the 13th embodiment in the wide-angle end state, Figure 25(b) is a cross-sectional view of the variable magnification optical system of the 13th embodiment in the intermediate focal length state, and Figure 25(c) is a cross-sectional view of the variable magnification optical system of the 13th embodiment in the telephoto end state.

[0329] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 negative refractive power, and a seventh lens group G7 having positive refractive power.

[0330] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0331] The second lens group G2 is made up of a biconvex positive lens L5.

[0332] The third lens group G3 is made up of a negative meniscus lens L6 with its concave surface facing the object side.

[0333] The fourth lens group G4 consists of, in order from the object side, a biconvex positive lens L7, an aperture stop S, a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9, a cemented negative lens consisting of a biconvex positive lens L10 and a biconcave negative lens L11, and a biconvex positive lens L12.

[0334] The fifth lens group G5 is composed of a cemented positive lens consisting of a meniscus-shaped positive lens L13 with a convex surface facing the object side and a meniscus-shaped negative lens L14 with a convex surface facing the object side.

[0335] The sixth lens group G6 is made up of a biconcave negative lens L15.

[0336] The seventh lens group G7 is composed of a positive meniscus lens L16 with its concave surface facing the object side.

[0337] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0338] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0339] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the third lens group G3 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the third lens group G3 corresponds to the second focusing lens group.

[0340] Table 13 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0341] (Table 13) [Overall specifications] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 3.018 ω 57.398 51.477 41.570 Y 21.700 21.700 21.700 TL 125.954 125.954 125.954 BF 12.567 11.882 11.682 [Lens specifications] m r d n(d) νd * 1) 77.5871 2.500 1.59255 67.86 * 2) 14.2238 14.729 3) 68.9794 1.600 1.77387 47.25 * 4) 41.9695 6.636 5) -55.4777 1.400 1.49782 82.57 6) 32.4445 5.195 1.85000 27.03 7) 132.9617 D7 * 8) 36.7823 3.469 1.58286 59.50 * 9) -956.3407 D9 10) -28.2184 1.200 1.49782 82.57 11) -248.9068 D11 12) 27.2596 5.319 1.48749 70.32 13) -57.8908 2.738 14> ∞ 1.000 (Aperture) 15) 33.5786 2.000 1.90265 35.77 16) 15.0000 6.756 1.55332 71.68 17) -51.3153 0.100 18) 352.5943 4.619 1.49782 82.57 19) -19.0000 1.200 1.90265 35.77 20) 120.3443 0.100 21) 30.1911 4.142 1.51823 58.82 22) -75.7131 D22 23) 29.1845 3.544 1.94594 17.98 24) 162.0348 1.776 1.85000 27.03 25) 25.6407 D25 *26) -169.1118 1.981 1.85135 40.10 *27) 500.0000 D27 28) -41.7160 4.053 1.49782 82.57 29) -27.5111 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 2.545E-06 -3.817E-09 4.642E-12 -2.916E-15 1.060E-18 2) 0.0772 1.515E-05 2.530E-08 1.535E-10 -5.237E-13 1.172E-15 4) 0.2922 5.879E-06 -2.242E-08 2.269E-10 -8.110E-13 1.667E-15 8) 1.0000 -2.200E-06 -4.622E-09 1.011E-09 -4.370E-12 3.503E-14 9) 1.0000 2.178E-06 1.720E-08 8.053E-10 -1.792E-12 2.978E-14 26) 1.0000 -7.719E-05 2.688E-07 1.104E-09 -2.326E-12 -1.431E-14 27) 1.0000 -5.011E-05 3.161E-07 1.082E-09 -3.915E-12 -2.779E-15 [Focal length data for each group] Group First surface Focal length G1 1 -18.846 G2 8 60.848 G3 10 -64.048 G4 12 28.992 G5 23 596.702 G6 26 -148.234 G7 28 148.234 [Variable interval data] When focusing at infinity When focusing at close range Wide-angle end Mid-range Telephoto end Wide-angle end Mid-range Telephoto end D7 16.778 12.000 4.610 17.929 13.923 7.828 D9 4.938 6.240 5.205 2.866 4.176 3.033 D11 3.751 3.126 2.547 4.671 3.268 1.501 D22 2.082 3.524 3.799 2.082 3.524 3.799 D25 7.028 7.383 9.810 7.028 7.383 9.810 D27 2.754 5.741 12.244 2.754 5.741 12.244 BF 12.567 11.882 11.682 12.567 11.882 11.682.

[0342] FIG. 26(a) is a diagram showing various aberrations of the variable magnification optical system of the thirteenth embodiment in the wide-angle end state, and FIG. 26(b) is a diagram showing various aberrations of the variable magnification optical system of the thirteenth embodiment in the telephoto end state.

[0343] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0344] (14th Embodiment) Figure 27(a) is a cross-sectional view of the variable magnification optical system of the 14th embodiment in the wide-angle end state, Figure 27(b) is a cross-sectional view of the variable magnification optical system of the 14th embodiment in the intermediate focal length state, and Figure 27(c) is a cross-sectional view of the variable magnification optical system of the 14th embodiment in the telephoto end state.

[0345] The variable magnification optical system of this embodiment has, in order from the object side, a first lens group G1 having negative refractive power, a second lens group G2 having positive refractive power, a third lens group G3 having negative 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 negative refractive power, and a seventh lens group G7 having positive refractive power.

[0346] The first lens group G1 consists of, in order from the object side, a meniscus negative lens L1 with a convex surface facing the object side, a meniscus negative lens L2 with a convex surface facing the object side, and a cemented negative lens consisting of a biconcave negative lens L3 and a meniscus positive lens L4 with a convex surface facing the object side.

[0347] The second lens group G2 is made up of a biconvex positive lens L5.

[0348] The third lens group G3 is made up of a negative meniscus lens L6 with its concave surface facing the object side.

[0349] The fourth lens group G4 consists of, in order from the object side, a biconvex positive lens L7, an aperture stop S, a cemented positive lens consisting of a meniscus negative lens L8 with its convex surface facing the object side and a biconvex positive lens L9, a cemented negative lens consisting of a meniscus positive lens L10 with its concave surface facing the object side and a biconcave negative lens L11, and a biconvex positive lens L12.

[0350] The fifth lens group G5 is composed of a cemented positive lens consisting of a meniscus-shaped positive lens L13 with a convex surface facing the object side and a meniscus-shaped negative lens L14 with a convex surface facing the object side.

[0351] The sixth lens group G6 is made up of a negative meniscus lens L15 with its concave surface facing the object side.

[0352] The seventh lens group G7 is made up of a negative meniscus lens L16 with its concave surface facing the object side.

[0353] On the image plane I, an image pickup element (not shown) made up of a CCD, a CMOS, or the like is disposed.

[0354] In the variable magnification optical system of this embodiment, the first lens group G1 corresponds to the front group and also corresponds to the front-side first lens group. The second lens group G2 to the seventh lens group G7 correspond to the rear group, and the second lens group G2 corresponds to the rear-side first lens group.

[0355] The variable magnification optical system of this embodiment focuses by moving the second lens group G2 and the third lens group G3 along the optical axis. When focusing on a close object from a state focused on infinity, the second lens group G2 is moved from the object side to the image plane side, and the third lens group G3 is moved from the image plane side to the object side. The second lens group G2 corresponds to the first focusing lens group, and the third lens group G3 corresponds to the second focusing lens group.

[0356] Table 14 below lists the values ​​of the specifications of the variable magnification optical system of this example.

[0357] (Table 14) [All elements] W M T f 14.420 17.000 23.280 FNo 2.912 2.912 2.938 ω 57.456 51.555 41.549 Y 21.700 21.700 21.700 TL 126.055 126.054 126.055 BF 14.322 12.672 11.616 [All elements] m r d n(d) νd * 1) 98.7377 2.500 1.59255 67.86 * 2) 14.2269 14.773 3) 57.7282 1.741 1.77387 47.25 * 4) 42.5068 6.288 5) -70.9415 1.400 1.49782 82.57 6) 27.0361 5.296 1.85000 27.03 7) 69.8239 D7 * 8) 37.9615 3.041 1.58286 59.50 * 9) -918.0513 D9 10) -28.2739 1.200 1.49782 82.57 11) -166.6903 D11 12) 27.1154 5.383 1.48749 70.32 13) -58.1784 2.945 14> ∞ 1.000 15) 34.6222 2.000 1.90265 35.77 16) 15.0194 7.050 1.55332 71.68 17) -41.8850 0.100 18) -914.2650 4.323 1.49782 82.57 19) -19.0000 1.200 1.90265 35.77 20) 97.8674 0.100 21) 30.7867 4.063 1.51823 58.82 22) -80.0039 D22 23) 31.2994 3.102 1.94594 17.98 24) 113.6100 1.200 1.85000 27.03 25) 33.2370 D25 *26) -500.0000 1.583 1.85135 40.10 *27) -1203.4752 D27 28) -51.6337 4.733 1.49782 82.57 29) -59.3265 BF [Aspheric data] m K A4 A6 A8 A10 A12 1) 1.0000 3.809E-06 -4.108E-09 4.433E-12 -2.996E-15 1.081E-18 2) 0.0495 1.337E-05 3.410E-08 1.549E-10 -5.378E-13 1.430E-15 4) 0.2011 7.776E-06 -3.079E-08 2.244E-10 -8.272E-13 1.640E-15 8) 1.0000 -1.769E-06 -1.221E-08 1.026E-09 -3.150E-12 4.379E-14 9) 1.0000 3.806E-06 1.440E-08 8.004E-10 -2.366E-13 3.887E-14 26) 1.0000 -6.655E-05 2.815E-07 1.137E-09 -2.659E-12 -1.615E-14 27) 1.0000 -4.316E-05 3.188E-07 1.260E-09 -3.277E-12 -1.146E-14 [Each group focal length data] Group starting plane focal length G1 1 -18.217 G2 8 62.617 G3 10 -68.594 G4 12 30.424 G5 23 179.698 G6 26 -1005.775 G7 28 -1005.468 [Variable interval data] Focusing at infinity Focusing at close range Wide-angle end Intermediate Telephoto end Wide-angle end Intermediate Telephoto end D7 16.693 11.564 3.870 17.815 13.418 6.346 D9 4.898 6.597 5.995 2.878 4.603 3.860 D11 3.654 2.827 1.841 4.552 2.966 1.500 D22 1.500 2.843 2.903 1.500 2.843 2.903 D25 7.864 9.009 12.904 7.864 9.009 12.904 D27 2.103 5.522 11.905 2.103 5.522 11.905 BF 14.322 12.672 11.616 14.322 12.672 11.616.

[0358] FIG. 28(a) is a diagram showing various aberrations of the variable magnification optical system of the 14th embodiment in the wide-angle end state, and FIG. 28(b) is a diagram showing various aberrations of the variable magnification optical system of the 14th embodiment in the telephoto end state.

[0359] From each aberration diagram, it can be seen that the variable magnification optical system of this example appropriately corrects various aberrations and has high optical performance.

[0360] According to each of the above embodiments, when zooming, the lens group arranged closest to the object side is fixed relative to the image plane, making it possible to realize a small-sized variable-magnification optical system with high optical performance.

[0361] The values ​​corresponding to the conditional expressions in each example are shown below.

[0362] fGFw is the focal length of the front group at the wide-angle end, fGR1 is the focal length of the first rear lens group, fGRw is the focal length of the rear group at the wide-angle end, fwsfp is the composite focal length from the lens closest to the object in the first rear lens group at the wide-angle end to the aperture stop, and fwsrp is the composite focal length from the aperture stop at the wide-angle end to the lens closest to the object in the lens group with negative refractive power that is located closest to the object on the image plane side of the aperture stop.

[0363] fGL2 is the focal length of the lens group located adjacent to the lens group located closest to the image plane on the object side, fGL1 is the focal length of the lens group located closest to the image plane, f1 is the focal length of the lens located closest to the object, and f2 is the focal length of the lens located adjacent to the lens located closest to the object on the image plane side.

[0364] fw is the focal length of the variable magnification optical system at the wide-angle end, BFw is the back focal length at the wide-angle end, fGS0 is the focal length of the lens group that is located adjacent to the lens group that is located closest to the object among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop, and fGS1n is the focal length of the lens group that is located closest to the object among the lens groups that have negative refractive power and are located closer to the image plane than the aperture stop.

[0365] fni is the composite focal length of the positive lens and negative lens arranged adjacent to each other and closest to the image plane in the front group. fG1 is the focal length of the first front lens group. fo1 is the focal length of the first focusing lens group, and fo2 is the focal length of the second focusing lens group. ωw is the half angle of view of the variable magnification optical system at the wide-angle end, and FNow is the F-number of the variable magnification optical system at the wide-angle end.

[0366] ndp is the refractive index for the d-line of the positive lens included in the cemented lens closest to the image surface, ndn is the refractive index for the d-line of the negative lens included in the cemented lens closest to the image surface, νdp is the Abbe number based on the d-line of the positive lens included in the cemented lens closest to the image surface, and νdn is the Abbe number based on the d-line of the negative lens included in the cemented lens closest to the image surface.

[0367] [Conditional expression corresponding values] Example No. Conditional expression 1st 2nd 3rd 4th 5th 6th 7th (1) (-fGFw) / fGR1 0.319 0.354 0.364 0.412 0.317 0.363 0.445 (2) (-fGFw) / fGRw 0.636 0.623 0.623 0.498 0.610 0.632 0.540 (3) fwsfp / fwsrp 2.119 2.672 2.746 1.792 1.885 2.218 0.666 (4) fGL2 / fGL1 0.032 -0.277 -0.273 -0.374 0.357 0.006 -0.035 (5) f1 / f2 0.466 0.517 0.502 0.199 0.375 0.440 0.380 (6) fw / BFw 1.406 1.283 1.359 1.276 0.817 1.406 1.406 (7) fGS0 / (-fGS1n) 0.877 1.427 1.371 1.302 0.629 0.948 0.732 (8) BFw / fGL1 -0.008 0.142 0.132 0.206 -0.118 -0.002 0.006 (9) (-f1) / fni -0.056 -0.048 -0.056 0.092 0.021 -0.075 -0.028 (10) (-f2) / fni -0.120 -0.094 -0.111 0.459 0.055 -0.171 -0.073 (11) f2 / fG1 3.846 3.519 3.612 6.445 4.212 4.117 4.321 (12) f1 / fG1 1.793 1.818 1.814 1.284 1.581 1.811 1.641 (13) |fo1 / fo2| 0.728 0.177 0.219 0.104 1.066 1.319 0.482 (14) ωw 57.145 57.382 57.414 59.591 57.332 57.210 57.537 (15) Fnow 2.912 2.912 2.912 2.912 2.912 2.912 2.912 (16) ndp / ndn 1.023 0.996 0.996 0.972 1.023 1.023 1.022 (17) νdp / νdn 0.503 0.556 0.556 0.617 0.503 0.503 0.575.

[0368] Example Number Conditional Expression 8th 9th 10th 11th 12th 13th 14th (1) (-fGFw) / fGR1 0.361 0.783 0.268 0.372 0.297 0.310 0.291 (2) (-fGFw) / fGRw 0.627 0.660 0.626 0.593 0.658 0.625 0.625 (3) fwsfp / fwsrp 2.268 2.108 0.996 1.594 1.093 0.560 0.567 (4) fGL2 / fGL1 0.030 -0.672 -0.300 -0.368 -0.413 -1.000 1.000 (5) f1 / f2 0.379 0.478 0.335 0.218 0.695 0.210 0.129 (6) fw / BFw 1.406 1.147 1.122 0.996 1.027 1.147 1.007 (7) fGS0 / (-fGS1n) 0.881 0.283 1.225 1.226 0.692 4.025 0.179 (8) BFw / fGL1 -0.007 0.262 0.163 0.257 0.164 0.085 -0.014 (9) (-f1) / fni -0.054 -0.262 -0.486 0.120 0.014 -0.132 -0.169 (10) (-f2) / fni -0.143 -0.548 -1.449 0.551 0.019 -0.631 -1.304 (11) f2 / fG1 4.468 4.652 6.880 5.986 2.793 7.544 12.036 (12) f1 / fG1 1.693 2.221 2.305 1.306 1.941 1.583 1.557 (13) |fo1 / fo2| - 2.253 0.763 0.554 0.873 0.950 0.913 (14) ωw 57.144 58.632 58.355 59.198 57.571 57.398 57.456 (15) Fnow 2.912 2.912 2.912 2.912 2.912 2.912 2.912 (16) ndp / ndn 1.023 1.054 0.972 0.972 1.052 1.052 1.052 (17) νdp / νdn 0.503 0.755 0.617 0.617 0.665 0.665 0.665.

[0369] The above examples are merely examples of the present invention, and the present invention is not limited to these. The following content can be appropriately adopted within the scope that does not impair the optical performance of the variable magnification optical system of this embodiment.

[0370] The variable magnification optical system of this embodiment may have an optical member such as a filter between the lens surface closest to the image plane and the image plane.

[0371] In the variable magnification optical system of this embodiment, the lens surface may be spherical or flat, or may be aspherical. A spherical or flat lens surface is preferred because it facilitates lens processing and assembly adjustment, and prevents degradation of optical performance due to errors in processing and assembly adjustment. Furthermore, a spherical or flat lens surface is preferred because it minimizes degradation of imaging performance when the image plane is displaced.

[0372] In the case where the lens surface is aspherical, the aspherical surface may be formed by grinding glass or by glass molding using a mold having an aspherical shape, or may be formed on the surface of a resin bonded to the surface of the glass. In addition, in the variable magnification optical system of this embodiment, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

[0373] The lens surfaces of the lenses constituting the variable magnification optical system of this embodiment may be coated with an anti-reflection coating that has high transmittance over a wide wavelength range, thereby reducing flare and ghosting and achieving high-contrast optical performance.

[0374] In the variable magnification optical system of this embodiment, instead of providing an independent member as the aperture stop, the role of the lens frame or the like may be substituted.

[0375] Next, an optical device equipped with the variable magnification optical system of this embodiment will be described with reference to Fig. 29. Fig. 29 is a schematic diagram of an optical device 1 equipped with the variable magnification optical system of this embodiment.

[0376] The optical device 1 is a so-called mirrorless camera with interchangeable lenses, which is provided with the variable magnification optical system according to the first embodiment as the photographic lens 2 .

[0377] In optical device 1, light from an object (subject) (not shown) is collected by photographic lens 2 and reaches image sensor 3. Image sensor 3 converts the light from the subject into image data. The image data is displayed on electronic viewfinder 4. This allows a photographer with their eye positioned at eyepoint EP to observe the subject.

[0378] 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 photograph a subject using the optical device 1.

[0379] Here, the variable magnification optical system of the first embodiment mounted as the photographing lens 2 in the optical device 1 is a variable magnification optical system with high optical performance. Therefore, the optical device 1 can achieve good optical performance. Note that even if an optical device is constructed that mounts the variable magnification optical system of any of the second to fourteenth embodiments mounted as the photographing lens 2, it can achieve the same effects as the optical device 1.

[0380] Finally, an outline of a method for manufacturing the variable magnification optical system of this embodiment will be described with reference to Fig. 30. Fig. 30 is a flow chart showing an outline of the method for manufacturing the variable magnification optical system of this embodiment.

[0381] The method for manufacturing the variable magnification optical system of this embodiment shown in FIG. 30 includes the following steps S11 to S14.

[0382] Step S11: Prepare a front group and a rear group including at least four lens groups.

[0383] Step S12: Of the at least four lens groups, the rear first lens group having positive refractive power is disposed closest to the object side of the rear group.

[0384] Step S13: The front first lens group, which is located closest to the object side of the front group, is fixed relative to the image plane during zooming.

[0385] Step S14: The variable magnification optical system is made to satisfy a predetermined conditional expression, which includes at least one of the following conditional expressions (1) and (2).

[0386] (1) 0.01 < (-fGFw) / fGR1 < 0.83, where fGFw is the focal length of the front group at the wide-angle end, and fGR1 is the focal length of the first rear lens group.

[0387] (2) 0.28 < (-fGFw) / fGRw < 0.74, where fGRw is the focal length of the rear group at the wide-angle end.

[0388] In the above-mentioned step S11, the rear group may be configured to have a plurality of lens groups.

[0389] According to the manufacturing method of the variable magnification optical system of this embodiment, the lens group arranged closest to the object is fixed with respect to the image plane during magnification variation, making it possible to manufacture a variable magnification optical system that is small in size and has high optical performance.

[0390] It should be understood that those skilled in the art can make various changes, substitutions, and alterations thereto without departing from the spirit and scope of the present disclosure.

[0391] S Aperture stop I Image plane 1 Optical device 2 Taking lens 3 Image sensor

Claims

1. A variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group having a plurality of lens groups and having positive refractive power overall, the lens group of said plurality of lens groups being the rear first lens group having positive refractive power and located closest to the object, wherein during magnification variation, the front first lens group located closest to the object among the at least one lens group of said front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and which satisfies the following conditional expression: 0.01 < (-fGFw) / fGR1 < 0.83 where, fGFw: focal length of said front group at the wide-angle end fGR1: focal length of said rear first lens group 2. A variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group having a plurality of lens groups having positive refractive power overall, the lens group of the plurality of lens groups being the rear first lens group having positive refractive power and located closest to the object, wherein, during magnification variation, the front first lens group located closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and which satisfies the following condition: 0.28 < (-fGFw) / fGRw < 0.74 where, fGFw: focal length of the front group at the wide-angle end fGRw: focal length of the rear group at the wide-angle end 3. The variable magnification optical system according to claim 1, which satisfies the following condition: 0.28<(-fGFw) / fGRw<0.74, where fGRw is the focal length of the rear group at the wide-angle end.

4. The variable magnification optical system according to claim 2, which satisfies the following condition: 0.01<(-fGFw) / fGR1<1.40, where fGR1 is the focal length of the rear first lens group.

5. A variable magnification optical system according to any one of claims 1 to 4, wherein the rear group has at least four lens groups, at least one of which has negative refractive power.

6. A variable magnification optical system according to any one of claims 1 to 5, wherein the rear group has an aperture stop and the following condition is satisfied: 0.01 < fwsfp / fwsrp < 3.50, where fwsfp is the composite focal length from the lens in the rear first lens group closest to the object at the wide-angle end to the aperture stop, and fwsrp is the composite focal length from the aperture stop at the wide-angle end to the lens located on the object side of the lens group with negative refractive power that is located on the image plane side closer to the object than the aperture stop.

7. A variable magnification optical system according to any one of claims 1 to 6, which satisfies the following condition: -1.10 < fGL2 / fGL1 < 1.50, where fGL2 is the focal length of the lens group arranged adjacent to the lens group arranged closest to the image plane on the object side, and fGL1 is the focal length of the lens group arranged closest to the image plane.

8. A variable magnification optical system according to any one of claims 1 to 7, which satisfies the following condition: 0.05 < f1 / f2 < 1.00, where f1 is the focal length of the lens located closest to the object, and f2 is the focal length of the lens located adjacent to the lens located closest to the object on the image plane side.

9. A variable magnification optical system according to any one of claims 1 to 8, which satisfies the following condition: 0.01<fw / BFw<1.70, where fw is the focal length of the variable magnification optical system at the wide-angle end, and BFw is the back focal length at the wide-angle end.

10. A variable magnification optical system according to any one of claims 1 to 9, wherein the rear group has an aperture stop and satisfies the following condition: 0.01 < fGS0 / (-fGS1n) < 5.00, where fGS0 is the focal length of the lens group located adjacent to the lens group located closest to the object among the lens groups with negative refractive power located closer to the image plane than the aperture stop, and fGS1n is the focal length of the lens group located closest to the object among the lens groups with negative refractive power located closer to the image plane than the aperture stop.

11. A variable magnification optical system according to any one of claims 1 to 10, which satisfies the following condition: -1.00<BFw / fGL1<1.00, where BFw is the back focal length at the wide-angle end, and fGL1 is the focal length of the lens group disposed closest to the image plane.

12. A variable magnification optical system according to any one of claims 1 to 11, wherein the front group has a positive lens arranged closest to the image plane, and a negative lens arranged adjacent to the positive lens on the object side.

13. A variable magnification optical system according to claim 12, which satisfies the following condition: -0.50 < (-f1) / fni < 0.18, where f1 is the focal length of the lens located closest to the object, and fni is the combined focal length of the positive and negative lenses located closest to the image plane in the front group and adjacent to each other.

14. A variable magnification optical system according to claim 12 or 13, which satisfies the following condition: -1.50 < (-f2) / fni < 0.70, where f2 is the focal length of the lens located adjacent to the image surface side of the lens located closest to the object, and fni is the composite focal length of the positive lens and negative lens located adjacent to each other on the image surface side of the front group.

15. A variable magnification optical system according to any one of claims 1 to 14, which satisfies the following condition: 2.20 < f2 / fG1 < 13.00, where f2 is the focal length of the lens arranged adjacent to the image plane side of the lens arranged closest to the object side, and fG1 is the focal length of the front first lens group.

16. A variable magnification optical system according to any one of claims 1 to 15, which satisfies the following condition: 1.10 < f1 / fG1 < 5.00, where f1 is the focal length of the lens located closest to the object, and fG1 is the focal length of the front first lens group.

17. A variable magnification optical system according to any one of claims 1 to 16, wherein the rear group has an aperture stop, and has at least one lens group with positive refractive power and one lens group with negative refractive power on the image plane side of a lens group including a lens arranged adjacent to the image plane side of the aperture stop.

18. A variable magnification optical system according to any one of claims 1 to 17, wherein the rear group has at least two cemented lenses each having a positive lens and a negative lens.

19. A variable magnification optical system according to any one of claims 1 to 18, comprising a first focusing lens group that moves during focusing and has at least one lens, and a second focusing lens group that is disposed on the image plane side of the first focusing lens group, moves during focusing along a locus different from that of the first focusing lens group, and has at least one lens, and which satisfies the following condition: 0.01 < |fo1 / fo2| < 5.00, where fo1: focal length of the first focusing lens group, fo2: focal length of the second focusing lens group.

20. A variable magnification optical system according to any one of claims 1 to 19, further comprising an aperture stop, and a focusing lens group having at least one lens, which moves during focusing, located closer to the object than the aperture stop.

21. A variable magnification optical system according to any one of claims 1 to 20, which satisfies the following condition: 50.00° < ωw < 85.00°, where ωw is the half angle of view of the variable magnification optical system at the wide-angle end.

22. A variable magnification optical system according to any one of claims 1 to 21, which satisfies the following condition: 1.40 < Fnow < 4.20, where Fnow is the F-number of the variable magnification optical system at the wide-angle end.

23. A variable magnification optical system according to any one of claims 1 to 22, which satisfies both of the following conditional expressions: 0.60 < ndp / ndn < 1.50 0.20 < vdp / vdn < 1.00 Where, ndp: refractive index for the d-line of the positive lens included in the cemented lens located closest to the image surface ndn: refractive index for the d-line of the negative lens included in the cemented lens located closest to the image surface vdp: Abbe number based on the d-line of the positive lens included in the cemented lens located closest to the image surface vdn: Abbe number based on the d-line of the negative lens included in the cemented lens located closest to the image surface 24. A variable magnification optical system according to any one of claims 1 to 23, wherein the rear group comprises at least six lens groups.

25. A variable magnification optical system according to any one of claims 1 to 24, comprising at least three lens groups each consisting of one lens element.

26. An optical instrument comprising a variable magnification optical system according to any one of claims 1 to 25.

27. A method for manufacturing a variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group comprising a plurality of lens groups having positive refractive power overall, the lens group located closest to the object among the plurality of lens groups being a rear-side first lens group having positive refractive power, wherein, during magnification variation, the front-side first lens group located closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and the lens groups are arranged so as to satisfy the following condition: 0.01 < (-fGFw) / fGR1 < 0.83 where, fGFw: focal length of the front group at the wide-angle end fGR1: focal length of the rear-side first lens group 28. A method for manufacturing a variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group comprising a plurality of lens groups having positive refractive power overall, the lens group of the plurality of lens groups being the rear first lens group having positive refractive power and located closest to the object, wherein, during magnification variation, the front first lens group located closest to the object among the at least one lens group included in the front group is fixed with respect to the image plane, and the spacing between adjacent lens groups changes, and the lens groups are arranged so as to satisfy the following condition: 0.28 < (-fGFw) / fGRw < 0.74 where, fGFw: focal length of the front group at the wide-angle end fGRw: focal length of the rear group at the wide-angle end 29. A variable magnification optical system having, in order from the object side, a front group consisting of at least one lens group each having negative refractive power, and a rear group having at least four lens groups having positive refractive power overall, the lens group of said at least four lens groups being the rear first lens group having positive refractive power and located closest to the object side, wherein the spacing between adjacent lens groups changes during magnification variation, and which satisfies the following condition: 0.01 < (-fGFw) / fGR1 < 0.83, where fGFw is the focal length of said front group at the wide-angle end, and fGR1 is the focal length of said rear first lens group.

Images