阅读说明：本技术 变倍光学系统以及摄像装置 (Variable magnification optical system and imaging device ) 是由 伊藤智希 山本浩史 于 2015-03-26 设计创作，主要内容包括：本发明提供一种变倍光学系统以及摄像装置。种变倍光学系统具备从物体侧依次排列的具有正的光焦度的第1透镜组、具有负的光焦度的第2透镜组及具有正的光焦度的第3透镜组,通过使所述第3透镜组的至少一部分作为对焦透镜组而沿着光轴方向移动来进行对焦,且满足以下条件式：0.90<f3/fw<1.50其中,f3：所述第3透镜组的焦距,fw：广角端状态下的整个系统的焦距。(The invention provides a variable magnification optical system and an imaging device. A variable power optical system includes a 1 st lens group having positive power, a 2 nd lens group having negative power, and a 3 rd lens group having positive power, which are arranged in order from an object side, and performs focusing by moving at least a part of the 3 rd lens group in an optical axis direction as a focusing lens group, and satisfies the following conditional expression: 0.90< f3/fw <1.50 wherein, f 3: focal length of the 3 rd lens group, fw: focal length of the entire system in the wide-angle end state.)

1. A variable power optical system is characterized in that,

comprises a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, which are arranged in this order from the object side,

focusing is performed by moving at least a part of the 3 rd lens group as a focusing lens group in an optical axis direction,

and satisfies the following conditional expressions:

0.90<f3/fw<1.50

wherein the content of the first and second substances,

f 3: a focal length of the 3 rd lens group,

fw: focal length of the entire system in the wide-angle end state.

2. The variable magnification optical system according to claim 1,

the magnification is changed by changing an air interval between the 1 st lens group and the 2 nd lens group, and an air interval between the 2 nd lens group and the 3 rd lens group.

3. The variable magnification optical system according to claim 1 or 2,

when zooming from a wide-angle end state to a telephoto end state, an air space between the 1 st lens group and the 2 nd lens group is expanded, and a space between the 2 nd lens group and the 3 rd lens group is narrowed.

4. The variable power optical system according to any one of claims 1 to 3,

the following conditional expressions are satisfied:

4.70<f1/f3<30.00

wherein the content of the first and second substances,

f 1: focal length of the 1 st lens group.

5. The variable power optical system according to any one of claims 1 to 4,

the following conditional expressions are satisfied:

0.60<(-f2)/f3<1.05

wherein the content of the first and second substances,

f 2: focal length of the 2 nd lens group.

6. The variable power optical system according to any one of claims 1 to 5,

the following conditional expressions are satisfied:

5.20<f1/(-f2)<30.00

wherein the content of the first and second substances,

f 1: a focal length of the 1 st lens group,

f 2: focal length of the 2 nd lens group.

7. The variable power optical system according to any one of claims 1 to 6,

is provided with a light ring and a light source,

the diaphragm is arranged between the 3 rd lens group and the image surface.

8. The variable power optical system according to any one of claims 1 to 7,

the following conditional expressions are satisfied:

30.00°<ωw<80.00°

wherein the content of the first and second substances,

ω w: half field angle in the wide-angle end state.

9. The variable power optical system according to any one of claims 1 to 8,

the following conditional expressions are satisfied:

2.00<ft/fw<15.00

wherein the content of the first and second substances,

ft: focal length of the whole system in the far focus end state.

10. The variable power optical system according to any one of claims 1 to 9,

the focusing lens group moves from the object side to the image side when changing to a state of focusing from an infinity object to a close object.

11. The variable power optical system according to any one of claims 1 to 10,

the 1 st lens group includes a cemented lens of a negative lens and a positive lens arranged in order from the object side.

12. The variable power optical system according to any one of claims 1 to 11,

the 1 st lens group moves to the object side while varying magnification from a wide-angle end state to a telephoto end state.

13. An imaging device comprising the variable power optical system according to any one of claims 1 to 12.

14. A variable power optical system is characterized in that,

comprises a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, which are arranged in this order from the object side,

moving the 1 st lens group in an object direction along an optical axis direction when zooming from a wide-angle end state to a telephoto end state,

focusing is performed by moving at least a part of the 3 rd lens group in an optical axis direction.

15. The magnification-varying optical system according to claim 14,

the following conditional expressions are satisfied:

0.73<(-f2)/f3<2.00

wherein the content of the first and second substances,

f 2: a focal length of the 2 nd lens group,

f 3: a focal length of the 3 rd lens group.

16. The variable magnification optical system according to claim 14 or 15,

the 3 rd lens group is composed of a 3A lens group and a 3B lens group having positive power arranged in order from the object side,

focusing is performed by moving the 3 rd lens group in the optical axis direction.

17. The variable power optical system according to any one of claims 14 to 16,

the following conditional expressions are satisfied:

1.00<f3A/f3<4.00

wherein the content of the first and second substances,

f 3A: a focal length of the 3A lens group.

18. The magnification-varying optical system according to claim 16,

the 3A lens group is composed of a single lens.

19. The magnification-varying optical system according to claim 16,

the following conditional expressions are satisfied:

1.00<|f3B|/f3<5.00

wherein the content of the first and second substances,

f 3B: a focal length of the 3B lens group.

20. The magnification-varying optical system according to claim 16,

at least a part of the 3B lens group is configured to be movable to have a component in a direction perpendicular to the optical axis as an anti-shake lens group for correcting image shake.

21. The magnification-varying optical system according to claim 20,

the anti-shake lens group has negative focal power.

22. The variable magnification optical system according to claim 20 or 21,

the following conditional expressions are satisfied:

2.00<|fvr|/f3<6.00

wherein the content of the first and second substances,

fvr: the focal length of the anti-shake lens group.

23. The variable power optical system according to any one of claims 20 to 22,

the anti-shake lens group is composed of a single lens.

24. An imaging device comprising the variable power optical system according to any one of claims 14 to 23.

Technical Field

The invention relates to a variable magnification optical system, an imaging device, and a method of manufacturing the variable magnification optical system.

Background

Conventionally, a variable magnification optical system suitable for a camera, an electronic still camera, a video camera, and the like has been proposed (for example, see patent documents 1 and 2).

Disclosure of Invention

Problems to be solved by the invention

However, the conventional variable magnification optical system has a problem that aberration fluctuation during variable magnification is large. In order to achieve higher image quality, it is desirable to provide an image blur correction mechanism for correcting image blur caused by hand blur or the like.

Further, the conventional variable power optical system has a problem that aberration variation during variable power and aberration variation during close-range photographing are large.

In recent years, there has been a demand for a variable magnification optical system having more excellent optical performance.

Means for solving the problems

A variable power optical system according to claim 1 includes, in order from an object side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, and is configured such that at least a part of the 2 nd lens group or at least a part of the 3 rd lens group is movable as an anti-shake lens group for correcting image blur so as to have a component in a direction perpendicular to an optical axis, and the following conditional expressions are satisfied:

4.40<f1/(-f2)<8.00

wherein the content of the first and second substances,

f 1: a focal length of the 1 st lens group,

f 2: focal length of the 2 nd lens group.

The imaging device of claim 1 includes the variable magnification optical system of claim 1.

A variable power optical system according to claim 2 includes, in order from an object side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, and is configured such that at least a part of the 2 nd lens group or at least a part of the 3 rd lens group is movable as an anti-shake lens group for correcting image blur so as to have a component in a direction perpendicular to an optical axis, and the following conditional expressions are satisfied:

3.60<f1/f3<8.00

wherein the content of the first and second substances,

f 1: a focal length of the 1 st lens group,

f 3: a focal length of the 3 rd lens group.

The imaging device of claim 2 includes the variable magnification optical system of claim 2.

A variable power optical system according to claim 3 includes, arranged in order from an object side, a 1 st lens group having positive power, a 2 nd lens group having negative power, and a 3 rd lens group having positive power, wherein when power is changed from a wide-angle end state to a telephoto end state, the 1 st lens group is moved in an optical axis direction toward the object side, and at least a part of the 3 rd lens group is moved in the optical axis direction to perform focusing, and the following conditional expressions are satisfied:

0.73<(-f2)/f3<2.00

wherein the content of the first and second substances,

f 2: a focal length of the 2 nd lens group,

f 3: a focal length of the 3 rd lens group.

The imaging device of claim 3 includes the variable magnification optical system of claim 3.

A variable power optical system according to claim 4 includes, in order from an object side, a 1 st lens group having positive power, a 2 nd lens group having negative power, and a 3 rd lens group having positive power, wherein the 1 st lens group is moved in an optical axis direction toward the object side when performing variable power from a wide-angle end state to a telephoto end state, and the following conditional expressions are satisfied:

0.14<fw/f1<0.26

0.77<fw/f3<1.05

wherein the content of the first and second substances,

fw: the focal length of the entire system in the wide-angle end state,

f 1: a focal length of the 1 st lens group,

f 3: a focal length of the 3 rd lens group.

The imaging device of claim 4 includes the variable magnification optical system of claim 4.

A variable power optical system according to claim 5 includes, in order from an object side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, and at least a part of the 3 rd lens group is moved in an optical axis direction as a focusing lens group to perform focusing, and the following conditional expressions are satisfied:

0.90<f3/fw<1.50

wherein the content of the first and second substances,

f 3: a focal length of the 3 rd lens group,

fw: focal length of the entire system in the wide-angle end state.

The imaging device of claim 5 includes the variable magnification optical system of claim 5.

A variable power optical system according to claim 6 includes, in order from an object side, a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, and is configured such that at least a part of the 3 rd lens group is movable as an anti-shake lens group for correcting image blur so as to have a component in a direction perpendicular to an optical axis, and the following conditional expressions are satisfied:

0.60<f3/fw<3.50

wherein the content of the first and second substances,

f 3: a focal length of the 3 rd lens group,

fw: focal length of the entire system in the wide-angle end state.

The imaging device according to claim 6 includes the variable magnification optical system according to claim 6.

A method for manufacturing a variable power optical system according to claim 1 includes a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, which are arranged in this order from an object side, and is configured such that at least a part of the 2 nd lens group or at least a part of the 3 rd lens group is movable as an anti-shake lens group for correcting shake so as to have a component in a direction perpendicular to an optical axis, and each lens is arranged in a lens barrel so as to satisfy the following conditional expressions:

4.40<f1/(-f2)<8.00

wherein the content of the first and second substances,

f 1: a focal length of the 1 st lens group,

f 2: focal length of the 2 nd lens group.

A method of manufacturing a variable power optical system according to claim 2 includes a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, which are arranged in this order from an object side, and is configured such that at least a part of the 2 nd lens group or at least a part of the 3 rd lens group is movable as an anti-shake lens group for correcting shake so as to have a component in a direction perpendicular to an optical axis, and each lens is arranged in a lens barrel so as to satisfy the following conditional expressions:

3.60<f1/f3<8.00

wherein the content of the first and second substances,

f 1: a focal length of the 1 st lens group,

f 3: a focal length of the 3 rd lens group.

A method for manufacturing a variable power optical system according to claim 3, wherein the variable power optical system includes a 1 st lens group having positive power, a 2 nd lens group having negative power, and a 3 rd lens group having positive power, which are arranged in this order from an object side, and wherein, when performing variable power from a wide-angle end state to a telephoto end state, the 1 st lens group is moved in an object direction along an optical axis direction, and focusing is performed by moving at least a part of the 3 rd lens group along the optical axis direction, and each lens is arranged in a lens barrel so as to satisfy the following conditional expressions:

0.73<(-f2)/f3<2.00

wherein the content of the first and second substances,

f 2: a focal length of the 2 nd lens group,

f 3: a focal length of the 3 rd lens group.

A method for manufacturing a variable power optical system according to claim 4, wherein the variable power optical system includes a 1 st lens group having positive power, a 2 nd lens group having negative power, and a 3 rd lens group having positive power, which are arranged in this order from an object side, and wherein the 1 st lens group is moved in an optical axis direction toward the object side when power is changed from a wide-angle end state to a telephoto end state, and each lens is arranged in a lens barrel so as to satisfy the following conditional expressions:

0.14<fw/f1<0.26

0.77<fw/f3<1.05

wherein the content of the first and second substances,

fw: the focal length of the entire system in the wide-angle end state,

f 1: a focal length of the 1 st lens group,

f 3: a focal length of the 3 rd lens group.

A method for manufacturing a variable power optical system according to claim 5, wherein the variable power optical system includes a 1 st lens group having positive power, a 2 nd lens group having negative power, and a 3 rd lens group having positive power, which are arranged in this order from an object side, and focusing is performed by moving at least a part of the 3 rd lens group in an optical axis direction, and each lens is arranged in a lens barrel so as to satisfy the following conditional expressions:

0.90<f3/fw<1.50

wherein the content of the first and second substances,

f 3: a focal length of the 3 rd lens group,

fw: focal length of the entire system in the wide-angle end state.

A method for manufacturing a variable power optical system according to claim 6 is a method for manufacturing a variable power optical system including a 1 st lens group having positive refractive power, a 2 nd lens group having negative refractive power, and a 3 rd lens group having positive refractive power, which are arranged in this order from an object side, wherein at least a part of the 3 rd lens group is configured to be movable as an anti-shake lens group for correcting image blur so as to have a component in a direction perpendicular to an optical axis, and each lens is disposed in a lens barrel so as to satisfy the following conditional expressions:

0.60<f3/fw<3.50

wherein the content of the first and second substances,

f 3: a focal length of the 3 rd lens group,

fw: focal length of the entire system in the wide-angle end state.

Drawings

Fig. 1 is a sectional view showing a lens structure of a variable magnification optical system of embodiment 1.

Fig. 2 is an aberration diagram in the wide-angle end state (f is 18.500) of the variable power optical system according to embodiment 1, fig. 2(a) shows each aberration diagram in infinity focusing, fig. 2(b) shows each aberration diagram in close focusing (photographing magnification β is-0.0196), and fig. 2(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 3 is an aberration diagram in the intermediate focal length state (f is 35.000) of the variable power optical system according to embodiment 1, fig. 3(a) shows each aberration diagram in infinity focusing, fig. 3(b) shows each aberration diagram in short-distance focusing (imaging magnification β is-0.0365), and fig. 3(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 4 is an aberration diagram in the far-focus end state (f is 53.500) of the variable power optical system according to embodiment 1, fig. 4(a) shows each aberration diagram in infinity focusing, fig. 4(b) shows each aberration diagram in short-distance focusing (imaging magnification β is-0.0554), and fig. 4(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 5 is a sectional view showing a lens structure of the variable magnification optical system of embodiment 2.

Fig. 6 is an aberration diagram in the wide-angle end state (f is 18.500) of the variable power optical system according to embodiment 2, fig. 6(a) shows each aberration diagram in infinity focusing, fig. 6(b) shows each aberration diagram in close-distance focusing (photographing magnification β is-0.0196), and fig. 6(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 7 is an aberration diagram in the intermediate focal length state (f is 34.176) of the variable power optical system according to embodiment 2, fig. 7(a) shows the aberration diagrams in infinity focusing, fig. 7(b) shows the aberration diagrams in close focusing (imaging magnification β is-0.0358), and fig. 7(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 8 is an aberration diagram in the far-focus end state (f is 53.500) of the variable power optical system according to embodiment 2, fig. 8(a) shows each aberration diagram in infinity focusing, fig. 8(b) shows each aberration diagram in short-distance focusing (imaging magnification β is-0.0556), and fig. 8(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 9 is a sectional view showing a lens structure of the variable magnification optical system of embodiment 3.

Fig. 10 is an aberration diagram in the wide-angle end state (f is 18.477) of the variable power optical system according to embodiment 3, fig. 10(a) shows each aberration diagram in infinity focusing, fig. 10(b) shows each aberration diagram in close focusing (photographing magnification β is-0.0194), and fig. 10(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 11 is an aberration diagram in the intermediate focal length state (f is 34.000) of the variable power optical system according to embodiment 3, fig. 11(a) shows each aberration diagram in infinity focusing, fig. 11(b) shows each aberration diagram in close focusing (imaging magnification β is-0.0355), and fig. 11(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 12 is an aberration diagram in the far-focus end state (f is 53.500) of the variable power optical system according to embodiment 3, fig. 12(a) shows each aberration diagram in infinity focusing, fig. 12(b) shows each aberration diagram in short-distance focusing (imaging magnification β is-0.0552), and fig. 12(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 13 is a sectional view showing a lens structure of the variable magnification optical system of embodiment 4.

Fig. 14 is an aberration diagram in the wide-angle end state (f is 18.500) of the variable power optical system according to embodiment 4, fig. 14(a) shows each aberration diagram in infinity focusing, fig. 14(b) shows each aberration diagram in close-distance focusing (photographing magnification β is-0.0194), and fig. 14(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 15 is an aberration diagram in the intermediate focal length state (f is 34.061) of the variable power optical system according to embodiment 4, fig. 15(a) shows the aberration diagrams in infinity focusing, fig. 15(b) shows the aberration diagrams in close focusing (imaging magnification β is-0.0355), and fig. 15(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 16 is an aberration diagram in the far-focus end state (f: 53.500) of the variable power optical system according to embodiment 4, fig. 16(a) shows each aberration diagram in infinity focusing, fig. 16(b) shows each aberration diagram in short-distance focusing (imaging magnification β: 0.0556), and fig. 16(c) shows a coma diagram when image blur correction is performed in infinity focusing (correction angle θ is 0.30 °).

Fig. 17 is a schematic sectional view showing the configuration of the camera according to embodiments 1 to 4.

Fig. 18 is a flowchart for explaining a method of manufacturing the variable magnification optical system according to embodiment 1.

Fig. 19 is a flowchart for explaining a method of manufacturing the variable magnification optical system according to embodiment 2.

Fig. 20 is a flowchart for explaining a method of manufacturing the variable magnification optical system according to embodiment 3.

Fig. 21 is a flowchart for explaining a method of manufacturing the variable magnification optical system according to embodiment 4.

Fig. 22 is a sectional view showing a lens structure of the variable magnification optical system of embodiment 5.

Fig. 23 is an aberration diagram in the wide-angle end state (f is 18.50) of the variable power optical system according to example 5, fig. 23(a) shows each aberration diagram in infinity focusing, fig. 23(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 23(c) shows each aberration diagram in short-distance focusing (photographing magnification β is-0.009).

Fig. 24 is an aberration diagram in the intermediate focal length state (f: 34.95) of the variable power optical system according to example 5, fig. 24(a) shows each aberration diagram in infinity focusing, fig. 24(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 24(c) shows each aberration diagram in close focusing (photographing magnification β is-0.018).

Fig. 25 is an aberration diagram in the far-focus end state (f is 53.50) of the variable power optical system according to embodiment 5, fig. 25(a) shows each aberration diagram in infinity focusing, fig. 25(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 25(c) shows each aberration diagram in near-distance focusing (photographing magnification β is-0.027).

Fig. 26 is a sectional view showing a lens structure of the variable magnification optical system of embodiment 6.

Fig. 27 is an aberration diagram in the wide-angle end state (f is 18.74) of the variable power optical system according to embodiment 6, fig. 27(a) shows each aberration diagram in infinity focusing, fig. 27(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 27(c) shows each aberration diagram in short-distance focusing (photographing magnification β is-0.010).

Fig. 28 is an aberration diagram in the intermediate focal length state (f is 34.50) of the variable power optical system according to embodiment 6, fig. 28(a) shows each aberration diagram in infinity focusing, fig. 28(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 28(c) shows each aberration diagram in short distance focusing (photographing magnification β is-0.018).

Fig. 29 is an aberration diagram in the far-focus end state (f is 52.08) of the variable power optical system according to embodiment 6, fig. 29(a) shows each aberration diagram in infinity focusing, fig. 29(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 29(c) shows each aberration diagram in near-distance focusing (photographing magnification β is-0.026).

Fig. 30 is a sectional view showing a lens structure of the variable magnification optical system of embodiment 7.

Fig. 31 is an aberration diagram in the wide-angle end state (f is 18.72) of the variable power optical system according to embodiment 7, fig. 31(a) shows each aberration diagram in infinity focusing, fig. 31(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 31(c) shows each aberration diagram in short-distance focusing (photographing magnification β is-0.010).

Fig. 32 is an aberration diagram in the intermediate focal length state (f is 35.50) of the variable power optical system according to example 7, fig. 32(a) shows each aberration diagram in infinity focusing, fig. 32(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 32(c) shows each aberration diagram in short-distance focusing (photographing magnification β is-0.018).

Fig. 33 is an aberration diagram in the far-focus end state (f is 52.00) of the variable power optical system according to embodiment 7, fig. 33(a) shows each aberration diagram in infinity focusing, fig. 33(b) shows a coma diagram when image blur correction is performed in infinity focusing (shift amount of the anti-shake lens group is 0.2mm), and fig. 33(c) shows each aberration diagram in near-distance focusing (photographing magnification β is-0.027).

Fig. 34 is a schematic sectional view showing the configuration of the camera according to embodiments 5 and 6.

Fig. 35 is a flowchart for explaining a method of manufacturing the variable magnification optical system according to embodiment 5.

Fig. 36 is a flowchart for explaining a method of manufacturing the variable magnification optical system according to embodiment 6.

Detailed Description

(1 st to 4 th embodiments)

Hereinafter, embodiment 1 will be described with reference to the drawings. As shown in fig. 1, the variable power optical system ZL of embodiment 1 is composed of a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power, which are arranged in this order from the object side.

With this configuration, it is possible to achieve downsizing of the lens barrel in the wide-angle end state and securing of a sufficient magnification ratio.

The variable magnification optical system ZL according to embodiment 1 is configured such that at least a part of the 2 nd lens group G2 or at least a part of the 3 rd lens group G3 is movable to have a component in a direction perpendicular to the optical axis as an anti-shake lens group for correcting image blur.

With this configuration, the image blur correction mechanism including the anti-blur lens group can be downsized.

Further, according to the above configuration, the following conditional expression (1) is satisfied.

4.40<f1/(-f2)<8.00…(1)

Wherein the content of the first and second substances,

f 1: the focal length of the 1 st lens group G1,

f 2: focal length of the 2 nd lens group G2.

Conditional expression (1) specifies an appropriate focal length of the 1 st lens group G1 with respect to the focal length of the 2 nd lens group G2. Satisfying the conditional expression (1) enables to realize excellent optical performance and downsizing of an optical system.

If the refractive power is lower than the lower limit value of conditional expression (1), the refractive power of the 1 st lens group G1 becomes strong, and it becomes difficult to correct coma, astigmatism, and field curvature in the telephoto end state, which is not preferable.

By setting the lower limit value of conditional expression (1) to 5.00, the effect of embodiment 1 can be reliably obtained.

When the upper limit value of the conditional expression (1) is exceeded, the power of the 2 nd lens group G2 becomes strong, and it becomes difficult to correct coma and astigmatism in the wide-angle end state, which is not preferable.

By setting the upper limit value of conditional expression (1) to 7.00, the effect of embodiment 1 can be reliably obtained.

In the variable magnification optical system ZL of embodiment 1, it is preferable that the magnification is changed by changing the air space between the 1 st lens group G1 and the 2 nd lens group G2 and the air space between the 2 nd lens group G2 and the 3 rd lens group G3.

With this configuration, it is possible to suppress spherical aberration and fluctuation of field curvature during magnification change, and to secure a sufficient magnification ratio.

In the variable power optical system ZL of embodiment 1, the 3 rd lens group G3 is preferably composed of a 31 st lens group G31, a 32 th lens group G32, and a 33 rd lens group G33 arranged in this order from the object side, and the 32 th lens group G32 is preferably configured to be movable as the anti-shake lens group so as to have a component in a direction perpendicular to the optical axis.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur). In addition, the image shake correction mechanism can be miniaturized.

In the variable power optical system ZL of embodiment 1, the 32 nd lens group G32 preferably has negative refractive power.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur).

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (2).

2.00<(-f32)/f3<6.00…(2)

Wherein the content of the first and second substances,

f 32: the focal length of the 32 nd lens group G32,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (2) specifies an appropriate focal length of the 32 th lens group G32 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (2) enables good optical performance in image blur correction (image blur prevention) and downsizing of the optical system.

If the value is less than the lower limit of the conditional expression (2), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (2) to 2.50, the effect of embodiment 1 can be reliably obtained.

If the upper limit value of the conditional expression (2) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state. Further, the power of the 32 nd lens group G32 becomes weak, and the amount of shift in image blur correction (anti-shake) increases, making it difficult to downsize the lens barrel, which is not preferable.

By setting the upper limit value of conditional expression (2) to 4.00, the effect of embodiment 1 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (3).

0.50<|f31|/f3<2.00…(3)

Wherein the content of the first and second substances,

f 31: the focal length of the 31 st lens group G31,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (3) specifies an appropriate focal length of the 31 st lens group G31 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (3) enables to realize excellent optical performance and downsizing of an optical system.

If the refractive power is lower than the lower limit value of the conditional expression (3), the refractive power of the 3 rd lens group G3 becomes weak, and it is difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (3) to 0.70, the effect of embodiment 1 can be reliably obtained.

When the upper limit value of the conditional expression (3) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (3) to 1.50, the effect of embodiment 1 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (4).

1.00<|f33|/f3…(4)

Wherein the content of the first and second substances,

f 33: the focal length of the 33 rd lens group G33,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (4) specifies an appropriate focal length of the 33 rd lens group G33 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (4) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of the conditional expression (4), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (4) to 2.00, the effect of embodiment 1 can be reliably obtained.

In the variable magnification optical system ZL of embodiment 1, the 32 nd lens group G32 is preferably formed of a single lens.

With this configuration, decentering coma and image plane fluctuation at the time of image blur correction can be favorably suppressed. In addition, the image shake correction mechanism can be miniaturized.

The variable magnification optical system ZL according to embodiment 1 preferably includes a stop S that moves in the optical axis direction integrally with the 3 rd lens group G3 during magnification change.

With this configuration, the lens barrel structure can be simplified and the lens barrel can be downsized.

The variable magnification optical system ZL according to embodiment 1 preferably includes a stop S disposed between the 2 nd lens group G2 and the image plane I.

With this configuration, the field curvature and the astigmatism can be corrected well.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (5).

30.00°<ωw<80.00°…(5)

Wherein the content of the first and second substances,

ω w: half field angle in the wide-angle end state.

The conditional expression (5) is a condition for defining the value of the angle of view in the wide-angle end state. Satisfying the conditional expression (5) can satisfactorily correct coma aberration, distortion, and field curvature while having a wide angle of view.

By setting the lower limit value of conditional expression (5) to 33.00 °, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (5) to 36.00 °, further favorable aberration correction can be performed.

By setting the upper limit value of conditional expression (5) to 77.00 °, more favorable aberration correction can be performed.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (6).

2.00<ft/fw<15.00…(6)

Wherein the content of the first and second substances,

ft: the focal length of the entire system in the far-focus state,

fw: focal length of the entire system in the wide-angle end state.

The conditional expression (6) is a condition for specifying a ratio of the focal length of the entire system in the telephoto end state to the focal length of the entire system in the wide-angle end state. This variable magnification optical system ZL can obtain a high zoom ratio and can satisfactorily correct spherical aberration and coma aberration by satisfying conditional expression (6).

By setting the lower limit value of conditional expression (6) to 2.30, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (6) to 2.50, further favorable aberration correction can be performed. By setting the lower limit of conditional expression (6) to 2.70, the effect of embodiment 1 can be exhibited to the maximum.

By setting the upper limit value of conditional expression (6) to 10.00, more favorable aberration correction can be performed. By setting the upper limit value of conditional expression (6) to 7.00, further favorable aberration correction can be performed.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (7).

3.60<f1/f3<8.00…(7)

Wherein the content of the first and second substances,

f 1: the focal length of the 1 st lens group G1,

f 3: focal length of the 3 rd lens group G3.

Conditional expression (7) specifies an appropriate focal length of the 1 st lens group G1 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (7) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of conditional expression (7), the power of the 1 st lens group G1 becomes strong, and correction of coma, astigmatism, and field curvature in the telephoto end state becomes difficult, which is not preferable.

By setting the lower limit value of conditional expression (7) to 3.80, the effect of embodiment 1 can be reliably obtained.

When the upper limit value of the conditional expression (7) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (7) to 7.00, the effect of embodiment 1 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expression (8).

0.73<(-f2)/f3<2.00…(8)

Wherein the content of the first and second substances,

f 2: the focal length of the 2 nd lens group G2,

f 3: focal length of the 3 rd lens group G3.

Conditional expression (8) specifies an appropriate focal length of the 2 nd lens group G2 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (8) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of conditional expression (8), the power of the 2 nd lens group G2 becomes strong, and it becomes difficult to correct coma and astigmatism in the wide-angle end state, which is not preferable.

By setting the lower limit value of conditional expression (8) to 0.75, the effect of embodiment 1 can be reliably obtained.

When the upper limit value of the conditional expression (8) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (8) to 1.20, the effect of embodiment 1 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 1 preferably satisfies the following conditional expressions (9) and (10).

0.14<fw/f1<0.26…(9)

0.77<fw/f3<1.05…(10)

Wherein the content of the first and second substances,

fw: the focal length of the entire system in the wide-angle end state,

f 1: the focal length of the 1 st lens group G1,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (9) specifies a focal length of the entire system in the wide-angle end state appropriately with respect to the focal length of the 1 st lens group G1. Satisfying the conditional expression (9) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of the conditional expression (9), the power of the 1 st lens group G1 becomes weak, and it becomes difficult to downsize the lens barrel. When the power of the 2 nd lens group G2 is strengthened in order to achieve downsizing, it is difficult to correct coma, astigmatism, and curvature of field, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (9) to 0.15, the effect of embodiment 1 can be reliably obtained.

When the upper limit value of the conditional expression (9) is exceeded, the power of the 1 st lens group G1 becomes strong, and it becomes difficult to correct coma, astigmatism, and field curvature in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (9) to 0.25, the effect of embodiment 1 can be reliably obtained.

The conditional expression (10) specifies a focal length of the entire system in the wide-angle end state as appropriate with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (10) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of the conditional expression (10), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (10) to 0.80, the effect of embodiment 1 can be reliably obtained.

When the upper limit value of the conditional expression (10) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration, coma aberration, and astigmatism, which is not preferable.

By setting the upper limit value of conditional expression (10) to 1.02, the effect of embodiment 1 can be reliably obtained.

The variable power optical system ZL of embodiment 1 preferably includes a 1 st lens group G1, a 2 nd lens group G2, a 3 rd lens group G3, and a 4 th lens group G4, which are arranged in this order from the object side, and changes the air space between the 3 rd lens group G3 and the 4 th lens group G4 during variable power.

With this configuration, it is possible to suppress spherical aberration and fluctuation of field curvature during magnification change, and to ensure a sufficient magnification ratio.

According to embodiment 1 described above, it is possible to realize a variable magnification optical system ZL having high optical performance while including an image blur correction mechanism.

Next, a camera (imaging apparatus) 1 including the above-described variable magnification optical system ZL will be described with reference to fig. 17. As shown in fig. 17, the camera 1 is a lens-interchangeable camera (so-called a non-reflex camera) including the zoom optical system ZL as the photographing lens 2.

In the camera 1, light from an object (subject) not shown is condensed by the photographing lens 2, and an object image is formed on an imaging surface of the imaging unit 3 via an OLPF (Optical low pass filter) not shown. Then, the image of the subject is photoelectrically converted by a photoelectric conversion element provided in the image pickup section 3 to generate an image of the subject. The image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject by the EVF 4.

When a release button, not shown, is pressed by the photographer, an image of the subject generated by the imaging unit 3 is stored in a memory, not shown. This enables the photographer to take a picture of the subject by the camera 1.

As will be understood from each of the examples described later, the variable magnification optical system ZL according to embodiment 1 mounted as the photographing lens 2 on the camera 1 has high optical performance while having an image blur correction mechanism due to its characteristic lens structure. Therefore, according to the camera 1, an imaging device having high optical performance while including an image blur correction mechanism can be realized.

Even when the zoom optical system ZL is mounted on a single-lens reflex type camera having a quick return mirror and observing an object through a finder optical system, the same effect as that of the camera 1 can be obtained. Even when the zoom optical system ZL is mounted on a video camera, the same effects as those of the camera 1 can be obtained.

Next, a method for manufacturing the variable magnification optical system ZL having the above-described configuration will be described in detail with reference to fig. 18. First, each lens is arranged in a lens barrel as follows: the zoom lens is constituted by a 1 ST lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power (step ST 110). At this time, at least a part of the 2 nd lens group G2 or at least a part of the 3 rd lens group G3 is configured to be movable so as to have a component in a direction perpendicular to the optical axis as an anti-shake lens group for correcting image shake (due to hand shake or the like) (step ST 120). Further, each lens is arranged in the lens barrel so as to satisfy at least the conditional expression (1) among the above conditional expressions (step ST 130).

4.40<f1/(-f2)<8.00…(1)

Wherein the content of the first and second substances,

f 1: the focal length of the 1 st lens group G1,

f 2: focal length of the 2 nd lens group G2.

As shown in fig. 1, an example of the lens arrangement in embodiment 1 is a cemented lens comprising, in order from the object side, a negative meniscus lens L11 with the convex surface facing the object side and a positive meniscus lens L12 with the convex surface facing the object side, as a 1 st lens group G1. In the 2 nd lens group G2, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side are disposed in this order from the object side. In the 3 rd lens group G3, a positive meniscus lens L31 having a concave surface facing the object side, a cemented lens of a double convex lens L32 and a double concave lens L33, a double concave lens L34, a double convex lens L35, a double convex lens L36, and a negative meniscus lens L37 having a concave surface facing the object side are disposed in this order from the object side. Each lens is disposed so as to satisfy the conditional expression (1) (the corresponding value of the conditional expression (1) is 5.33).

According to the method of manufacturing a variable magnification optical system of embodiment 1 described above, it is possible to obtain a variable magnification optical system ZL having high optical performance while including an image blur correction mechanism.

Next, embodiment 2 will be described with reference to the drawings. As shown in fig. 1, the variable power optical system ZL of embodiment 2 includes, in order from the object side, a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power.

With this configuration, it is possible to achieve downsizing of the lens barrel in the wide-angle end state and securing of a sufficient magnification ratio.

The variable magnification optical system ZL according to embodiment 2 is configured such that at least a part of the 2 nd lens group G2 or at least a part of the 3 rd lens group G3 is movable to have a component in a direction perpendicular to the optical axis as an anti-shake lens group for correcting image blur.

With this configuration, the image blur correction mechanism including the anti-blur lens group can be downsized.

Further, according to the above configuration, the following conditional expression (11) is satisfied.

3.60<f1/f3<8.00…(11)

Wherein the content of the first and second substances,

f 1: the focal length of the 1 st lens group G1,

f 3: focal length of the 3 rd lens group G3.

Conditional expression (11) specifies an appropriate focal length of the 1 st lens group G1 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (11) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of conditional expression (11), the power of the 1 st lens group G1 becomes strong, and correction of coma, astigmatism, and field curvature in the telephoto end state becomes difficult, which is not preferable.

By setting the lower limit value of conditional expression (11) to 3.80, the effect of embodiment 2 can be reliably obtained.

When the upper limit value of the conditional expression (11) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (11) to 7.00, the effect of embodiment 2 can be reliably obtained.

In the variable magnification optical system ZL according to embodiment 2, it is preferable that the magnification is changed by changing an air space between the 1 st lens group G1 and the 2 nd lens group G2, an air space between the 2 nd lens group G2 and the 3 rd lens group G3, and an air space between the 3 rd lens group G3 and the 4 th lens group G4.

With this configuration, it is possible to suppress spherical aberration and fluctuation of field curvature during magnification change, and to ensure a sufficient magnification ratio.

In the variable power optical system ZL according to embodiment 2, the 3 rd lens group G3 preferably includes, in order from the object side, a 31 st lens group G31, a 32 nd lens group G32, and a 33 rd lens group G33, and the 32 th lens group G32 is preferably configured as the anti-shake lens group so as to be movable with a component in a direction perpendicular to the optical axis.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur). In addition, the image shake correction mechanism can be miniaturized.

In the variable power optical system ZL of embodiment 2, the 32 nd lens group G32 preferably has negative refractive power.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur).

The variable magnification optical system ZL according to embodiment 2 preferably satisfies the following conditional expression (12).

2.00<(-f32)/f3<6.00…(12)

Wherein the content of the first and second substances,

f 32: the focal length of the 32 nd lens group G32,

f 3: focal length of the 3 rd lens group G3.

Conditional expression (12) specifies an appropriate focal length of the 32 th lens group G32 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (12) enables good optical performance in image blur correction (image blur prevention) and downsizing of the optical system.

If the value is less than the lower limit of the conditional expression (12), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (12) to 2.50, the effect of embodiment 2 can be reliably obtained.

When the upper limit value of the conditional expression (12) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state. Further, the power of the 32 nd lens group G32 becomes weak, and the amount of shift in image blur correction (anti-shake) increases, making it difficult to downsize the lens barrel, which is not preferable.

By setting the upper limit value of conditional expression (12) to 4.00, the effect of embodiment 2 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 2 preferably satisfies the following conditional expression (13).

0.50<|f31|/f3<2.00…(13)

Wherein the content of the first and second substances,

f 31: the focal length of the 31 st lens group G31,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (13) specifies an appropriate focal length of the 31 st lens group G31 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (13) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit value of the conditional expression (13), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (13) to 0.70, the effect of embodiment 2 can be reliably obtained.

When the upper limit value of the conditional expression (13) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (13) to 1.50, the effect of embodiment 2 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 2 preferably satisfies the following conditional expression (14).

1.00<|f33|/f3…(14)

Wherein the content of the first and second substances,

f 33: the focal length of the 33 rd lens group G33,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (14) specifies an appropriate focal length of the 33 rd lens group G33 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (14) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of the conditional expression (14), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (14) to 2.00, the effect of embodiment 2 can be reliably obtained.

In the variable magnification optical system ZL of embodiment 2, the 32 nd lens group G32 is preferably formed of a single lens.

With this configuration, decentering coma and image plane variation in image blur correction can be corrected satisfactorily. In addition, the image shake correction mechanism can be miniaturized.

The variable magnification optical system ZL according to embodiment 2 preferably includes a stop S that moves in the optical axis direction integrally with the 3 rd lens group G3 during magnification change.

With this configuration, the lens barrel structure can be simplified and the lens barrel can be downsized.

The variable magnification optical system ZL according to embodiment 2 preferably includes a stop S disposed between the 2 nd lens group G2 and the image plane I.

With this configuration, the field curvature and the astigmatism can be corrected well.

The variable magnification optical system ZL according to embodiment 2 preferably satisfies the following conditional expression (15).

30.00°<ωw<80.00°…(15)

Wherein the content of the first and second substances,

ω w: half field angle in the wide-angle end state.

The conditional expression (15) is a condition for defining the value of the angle of view in the wide-angle end state. Satisfying this conditional expression (15) makes it possible to satisfactorily correct coma aberration, distortion, and field curvature while having a wide angle of view.

By setting the lower limit value of conditional expression (15) to 33.00 °, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (15) to 36.00 °, further favorable aberration correction can be performed.

By setting the upper limit value of conditional expression (15) to 77.00 °, more favorable aberration correction can be performed.

The variable magnification optical system ZL according to embodiment 2 preferably satisfies the following conditional expression (16).

2.00<ft/fw<15.00…(16)

Wherein the content of the first and second substances,

ft: the focal length of the entire system in the far-focus state,

fw: focal length of the entire system in the wide-angle end state.

The conditional expression (16) is a condition for specifying a ratio of the focal length of the entire system in the telephoto end state to the focal length of the entire system in the wide-angle end state. This variable magnification optical system ZL can obtain a high zoom ratio and can satisfactorily correct spherical aberration and coma aberration by satisfying conditional expression (16).

By setting the lower limit value of conditional expression (16) to 2.30, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (16) to 2.50, further favorable aberration correction can be performed. By setting the lower limit of conditional expression (16) to 2.70, the effect of embodiment 2 can be exhibited to the maximum.

By setting the upper limit value of conditional expression (16) to 10.00, more favorable aberration correction can be performed. By setting the upper limit value of conditional expression (16) to 7.00, further favorable aberration correction can be performed.

According to embodiment 2 described above, it is possible to realize a variable magnification optical system ZL having high optical performance while including an image blur correction mechanism.

Next, a camera (imaging apparatus) 1 including the above-described variable magnification optical system ZL will be described with reference to fig. 17. The camera 1 is the same as the camera of embodiment 1, and the configuration thereof has already been described, and therefore, the description thereof is omitted here.

As will be understood from the respective examples described later, the variable magnification optical system ZL according to embodiment 2 mounted on the camera 1 as the photographing lens 2 has high optical performance while having an image blur correction mechanism due to its characteristic lens structure. Therefore, according to the camera 1, an imaging device having high optical performance while including an image blur correction mechanism can be realized.

Even if the zoom optical system ZL is mounted on a single-lens reflex type camera having a quick return mirror and observing an object through a finder optical system, the same effect as that of the camera 1 can be obtained. Even when the zoom optical system ZL is mounted on a video camera, the same effects as those of the camera 1 can be obtained.

Next, a method for manufacturing the variable magnification optical system ZL having the above-described configuration will be described in detail with reference to fig. 19. First, each lens is arranged in a lens barrel as follows: the present invention is provided with a 1 ST lens group G1 having positive refractive power, a 2 nd lens group G2 having negative refractive power, and a 3 rd lens group G3 having positive refractive power (step ST 210). At this time, at least a part of the 2 nd lens group G2 or at least a part of the 3 rd lens group G3 is configured to be movable so as to have a component in a direction perpendicular to the optical axis as an anti-shake lens group for correcting image shake (due to hand shake or the like) (step ST 220). Further, each lens is arranged in the lens barrel so as to satisfy at least conditional expression (11) of the above conditional expressions (step ST 230).

3.60<f1/f3<8.00…(11)

Wherein the content of the first and second substances,

f 1: the focal length of the 1 st lens group G1,

f 3: focal length of the 3 rd lens group G3.

As shown in fig. 1, an example of the lens arrangement according to embodiment 2 is a cemented lens comprising, in order from the object side, a negative meniscus lens L11 with the convex surface facing the object side and a positive meniscus lens L12 with the convex surface facing the object side, as the 1 st lens group G1. In the 2 nd lens group G2, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side are disposed in this order from the object side. In the 3 rd lens group G3, a positive meniscus lens L31 having a concave surface facing the object side, a cemented lens of a double convex lens L32 and a double concave lens L33, a double concave lens L34, a double convex lens L35, a double convex lens L36, and a negative meniscus lens L37 having a concave surface facing the object side are disposed in this order from the object side. Each lens is disposed so as to satisfy the conditional expression (11) (the corresponding value of the conditional expression (11) is 4.06).

According to the method of manufacturing a variable magnification optical system of embodiment 2 described above, it is possible to obtain a variable magnification optical system ZL having high optical performance while including an image blur correction mechanism.

Next, embodiment 3 will be described with reference to the drawings. As shown in fig. 1, the variable power optical system ZL of embodiment 3 is composed of a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power, which are arranged in this order from the object side.

With this configuration, it is possible to achieve downsizing of the lens barrel in the wide-angle end state and securing of a sufficient magnification ratio.

The variable power optical system ZL according to embodiment 3 moves the 1 st lens group G1 in the optical axis direction toward the object when varying power from the wide-angle end state to the telephoto end state.

With this configuration, a sufficient zoom ratio can be ensured.

The variable magnification optical system ZL of embodiment 3 performs focusing by moving at least a part of the 3 rd lens group G3 in the optical axis direction.

With this configuration, aberration variation (for example, spherical aberration) in focusing can be suppressed.

Further, according to the above configuration, the following conditional expression (17) is satisfied.

0.73<(-f2)/f3<2.00…(17)

Wherein the content of the first and second substances,

f 2: the focal length of the 2 nd lens group G2,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (17) specifies an appropriate focal length of the 2 nd lens group G2 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (17) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of conditional expression (17), the power of the 2 nd lens group G2 becomes strong, and it becomes difficult to correct coma and astigmatism in the wide-angle end state, which is not preferable.

By setting the lower limit value of conditional expression (17) to 0.75, the effect of embodiment 3 can be reliably obtained.

When the upper limit value of the conditional expression (17) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (17) to 1.20, the effect of embodiment 3 can be reliably obtained.

In the variable magnification optical system ZL according to embodiment 3, it is preferable that the magnification is changed by changing the air space between the 1 st lens group G1 and the 2 nd lens group G2 and the air space between the 2 nd lens group G2 and the 3 rd lens group G3.

With this configuration, it is possible to suppress spherical aberration and fluctuation of field curvature during magnification change, and to ensure a sufficient magnification ratio.

In the variable magnification optical system ZL of embodiment 3, the 3 rd lens group G3 is preferably composed of a 3 rd a lens group G3A and a 3 rd B lens group G3B having positive refractive power arranged in order from the object side, and focusing is preferably performed by moving the 3 rd a lens group G3A in the optical axis direction.

With this configuration, aberration variation (for example, spherical aberration) in focusing can be suppressed.

The variable magnification optical system ZL according to embodiment 3 preferably satisfies the following conditional expression (18).

1.00<f3A/f3<4.00…(18)

Wherein the content of the first and second substances,

f 3A: focal length of the 3 rd a lens group G3A.

The conditional expression (18) specifies an appropriate focal length of the 3 rd a lens group G3A with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (18) enables good optical performance in focusing and miniaturization of the optical system.

If the value is less than the lower limit value of the conditional expression (18), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (18) to 1.50, the effect of embodiment 3 can be reliably obtained.

When the upper limit value of the conditional expression (18) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (18) to 3.50, the effect of embodiment 3 can be reliably obtained.

In the variable magnification optical system ZL of embodiment 3, the 3 rd a lens group G3A is preferably formed of a single lens.

With this configuration, the focusing mechanism can be downsized.

The variable magnification optical system ZL according to embodiment 3 preferably satisfies the following conditional expression (19).

1.00<|f3B|/f3<5.00…(19)

Wherein the content of the first and second substances,

f 3B: focal length of the 3B lens group G3B.

The conditional expression (19) specifies an appropriate focal length of the 3B lens group G3B with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (19) enables to realize excellent optical performance and downsizing of the optical system.

If the value is less than the lower limit value of the conditional expression (19), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (19) to 1.20, the effect of embodiment 3 can be reliably obtained.

When the upper limit value of the conditional expression (19) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (19) to 3.00, the effect of embodiment 3 can be reliably obtained.

In the variable magnification optical system ZL according to embodiment 3, it is preferable that at least a part of the 3B lens group G3B be movable to have a component in a direction perpendicular to the optical axis as the anti-shake lens group VR for correcting image shake.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur). In addition, the image blur correction mechanism including the anti-blur lens group VR can be downsized.

In the variable power optical system ZL according to embodiment 3, the anti-shake lens group VR preferably has negative refractive power.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur).

The variable magnification optical system ZL according to embodiment 3 preferably satisfies the following conditional expression (20).

2.00<|fvr|/f3<6.00…(20)

Wherein the content of the first and second substances,

fvr: the focal length of the anti-shake lens group VR.

The conditional expression (20) specifies an appropriate focal length of the anti-shake lens group VR with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (20) enables good optical performance in image blur correction and miniaturization of an optical system.

If the value is less than the lower limit value of the conditional expression (20), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (20) to 2.50, the effect of embodiment 3 can be reliably obtained.

When the upper limit value of the conditional expression (20) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state. Further, the power of the anti-shake lens group VR is weak, and the amount of shift in image shake correction (anti-shake) increases, which makes it difficult to downsize the lens barrel, and is therefore not preferable.

By setting the upper limit value of conditional expression (20) to 4.00, the effect of embodiment 3 can be reliably obtained.

In the variable magnification optical system ZL according to embodiment 3, the anti-shake lens group VR is preferably formed of a single lens.

With this configuration, the image shake correction mechanism can be miniaturized.

The variable magnification optical system ZL according to embodiment 3 preferably includes a stop S that moves in the optical axis direction integrally with the 3 rd lens group G3 during magnification change.

With this configuration, the lens barrel structure can be simplified and the lens barrel can be downsized.

The variable magnification optical system ZL according to embodiment 3 preferably includes a stop S disposed between the 2 nd lens group G2 and the image plane I.

With this configuration, the field curvature and the astigmatism can be corrected well.

The variable magnification optical system ZL according to embodiment 3 preferably satisfies the following conditional expression (21).

30.00°<ωw<80.00°…(21)

Wherein the content of the first and second substances,

ω w: half field angle in the wide-angle end state.

The conditional expression (21) is a condition for defining a value of the angle of view in the wide-angle end state. By satisfying this conditional expression (21), coma aberration, distortion, and field curvature can be corrected satisfactorily while having a wide angle of view.

By setting the lower limit value of conditional expression (21) to 33.00 °, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (21) to 36.00 °, further favorable aberration correction can be performed.

By setting the upper limit value of conditional expression (21) to 77.00 °, better aberration correction can be performed.

The variable magnification optical system ZL according to embodiment 3 preferably satisfies the following conditional expression (22).

2.00<ft/fw<15.00…(22)

Wherein the content of the first and second substances,

ft: the focal length of the entire system in the far-focus state,

fw: focal length of the entire system in the wide-angle end state.

The conditional expression (22) is a condition for specifying a ratio of the focal length of the entire system in the telephoto end state to the focal length of the entire system in the wide-angle end state. This variable magnification optical system ZL can obtain a high zoom ratio and can satisfactorily correct spherical aberration and coma aberration by satisfying the conditional expression (22).

By setting the lower limit of conditional expression (22) to 2.30, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (22) to 2.50, further favorable aberration correction can be performed. By setting the lower limit of conditional expression (22) to 2.70, the effect of embodiment 3 can be exhibited to the maximum.

By setting the upper limit value of conditional expression (22) to 10.00, more favorable aberration correction can be performed. By setting the upper limit value of conditional expression (22) to 7.00, further favorable aberration correction can be performed.

According to embodiment 3 as described above, the variable magnification optical system ZL having high optical performance can be realized.

Next, a camera (imaging apparatus) 1 including the above-described variable magnification optical system ZL will be described with reference to fig. 17. The camera 1 is the same as the camera of embodiment 1, and the configuration thereof has already been described, and therefore, the description thereof is omitted here.

As will be understood from each of the examples described later, the variable magnification optical system ZL according to embodiment 3 mounted on the camera 1 as the photographing lens 2 has high optical performance due to its characteristic lens structure. Therefore, according to the camera 1, an image pickup apparatus having high optical performance can be realized.

Even when the zoom optical system ZL is mounted on a single-lens reflex type camera having a quick return mirror and observing an object through a finder optical system, the same effect as that of the camera 1 can be obtained. Even when the zoom optical system ZL is mounted on a video camera, the same effects as those of the camera 1 can be obtained.

Next, a method for manufacturing the variable magnification optical system ZL having the above-described configuration will be described in detail with reference to fig. 20. First, each lens is arranged in a lens barrel as follows: the zoom lens is constituted by a 1 ST lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power (step ST 310). At this time, each lens is arranged as follows: when zooming is performed from the wide-angle end state to the telephoto end state, the 1 ST lens group G1 moves in the object direction along the optical axis direction (step ST 320). Each lens is arranged so that focusing is performed by moving at least a part of the 3 rd lens group G3 in the optical axis direction (step ST 330). Further, each lens is arranged in the lens barrel so as to satisfy at least conditional expression (17) among the above conditional expressions (step ST 340).

0.73<(-f2)/f3<2.00…(17)

Wherein the content of the first and second substances,

f 2: the focal length of the 2 nd lens group G2,

f 3: focal length of the 3 rd lens group G3.

As shown in fig. 1, an example of the lens arrangement according to embodiment 3 is a cemented lens comprising, in order from the object side, a negative meniscus lens L11 with the convex surface facing the object side and a positive meniscus lens L12 with the convex surface facing the object side, as the 1 st lens group G1. In the 2 nd lens group G2, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side are disposed in this order from the object side. In the 3 rd lens group G3, a positive meniscus lens L31 having a concave surface facing the object side, a cemented lens of a double convex lens L32 and a double concave lens L33, a double concave lens L34, a double convex lens L35, a double convex lens L36, and a negative meniscus lens L37 having a concave surface facing the object side are disposed in this order from the object side. Further, each lens is disposed so as to satisfy the conditional expression (17) (the corresponding value of the conditional expression (17) is 0.76).

According to the method for manufacturing a variable magnification optical system of embodiment 3 described above, a variable magnification optical system ZL having high optical performance can be obtained.

Next, embodiment 4 will be described with reference to the drawings. As shown in fig. 1, the variable power optical system ZL of embodiment 4 includes, in order from the object side, a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power.

With this configuration, the lens barrel in the wide-angle end state can be downsized.

The variable power optical system ZL according to embodiment 4 moves the 1 st lens group G1 in the optical axis direction toward the object when varying power from the wide-angle end state to the telephoto end state.

With this configuration, a sufficient zoom ratio can be ensured.

Further, according to the above configuration, the following conditional expressions (23) and (24) are satisfied.

0.14<fw/f1<0.26…(23)

0.77<fw/f3<1.05…(24)

Wherein the content of the first and second substances,

fw: the focal length of the entire system in the wide-angle end state,

f 1: the focal length of the 1 st lens group G1,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (23) specifies a focal length of the entire system in the wide-angle end state as appropriate with respect to the focal length of the 1 st lens group G1. Satisfying the conditional expression (23) enables to realize excellent optical performance and downsizing of the optical system.

If the value is less than the lower limit of the conditional expression (23), the power of the 1 st lens group G1 becomes weak, and it becomes difficult to downsize the lens barrel. When the power of the 2 nd lens group G2 is strengthened in order to achieve downsizing, it is difficult to correct coma, astigmatism, and curvature of field, and therefore, such is not preferable.

By setting the lower limit of conditional expression (23) to 0.15, the effect of embodiment 4 can be reliably obtained.

If the value is less than the upper limit of conditional expression (23), the power of the 1 st lens group G1 becomes strong, and correction of coma, astigmatism, and field curvature in the telephoto end state becomes difficult, which is not preferable.

By setting the upper limit value of conditional expression (23) to 0.25, the effect of embodiment 4 can be reliably obtained.

The conditional expression (24) specifies a focal length of the entire system in the wide-angle end state as appropriate with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (24) enables to realize excellent optical performance and downsizing of the optical system.

If the value is less than the lower limit of the conditional expression (24), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (24) to 0.80, the effect of embodiment 4 can be reliably obtained.

When the upper limit value of the conditional expression (24) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration, coma aberration, and astigmatism, which is not preferable.

By setting the upper limit value of conditional expression (24) to 1.02, the effect of embodiment 4 can be reliably obtained.

In the variable magnification optical system ZL according to embodiment 4, it is preferable that the magnification is changed by changing an air space between the 1 st lens group G1 and the 2 nd lens group G2, an air space between the 2 nd lens group G2 and the 3 rd lens group G3, and an air space between the 3 rd lens group G3 and the 4 th lens group G4.

With this configuration, it is possible to suppress spherical aberration and fluctuation of field curvature during magnification change, and to ensure a sufficient magnification ratio.

The variable magnification optical system ZL according to embodiment 4 is preferably configured such that at least a part of the 2 nd lens group G2 or at least a part of the 3 rd lens group G3 is movable to have a component in a direction perpendicular to the optical axis as an anti-shake lens group for correcting image shake (due to hand shake or the like).

With this configuration, the image blur correction mechanism including the anti-blur lens group can be downsized.

In the variable magnification optical system ZL according to embodiment 4, it is preferable that focusing is performed by moving at least a part of the 3 rd lens group G3 in the optical axis direction.

With this configuration, aberration variation (for example, spherical aberration) in focusing can be suppressed.

In the variable power optical system ZL according to embodiment 4, the 3 rd lens group G3 preferably includes, in order from the object side, a 31 st lens group G31, a 32 nd lens group G32, and a 33 rd lens group G33, and the 32 th lens group G32 is preferably configured as the anti-shake lens group so as to be movable with a component in a direction perpendicular to the optical axis.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur). In addition, the image shake correction mechanism can be miniaturized.

In the variable power optical system ZL of embodiment 4, the 32 nd lens group G32 preferably has negative power.

With this configuration, it is possible to realize excellent optical performance in image blur correction (anti-blur).

The variable magnification optical system ZL according to embodiment 4 preferably satisfies the following conditional expression (25).

2.00<(-f32)/f3<6.00…(25)

Wherein the content of the first and second substances,

f 32: the focal length of the 32 nd lens group G32,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (25) specifies an appropriate focal length of the 32 th lens group G32 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (25) enables good optical performance in image blur correction (image blur prevention) and downsizing of the optical system.

If the value is less than the lower limit value of the conditional expression (25), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (25) to 2.50, the effect of embodiment 4 can be reliably obtained.

When the upper limit value of the conditional expression (25) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state. Further, the power of the 32 nd lens group G32 becomes weak, and the amount of shift in image blur correction (anti-shake) increases, making it difficult to downsize the lens barrel, which is not preferable.

By setting the upper limit value of conditional expression (25) to 4.00, the effect of embodiment 4 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 4 preferably satisfies the following conditional expression (26).

0.50<|f31|/f3<2.00…(26)

Wherein the content of the first and second substances,

f 31: the focal length of the 31 st lens group G31,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (26) specifies an appropriate focal length of the 31 st lens group G31 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (26) enables to realize excellent optical performance and downsizing of an optical system.

If the value is less than the lower limit of the conditional expression (26), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit of conditional expression (26) to 0.70, the effect of embodiment 4 can be reliably obtained.

When the upper limit value of the conditional expression (26) is exceeded, the power of the 3 rd lens group G3 becomes strong, and it becomes difficult to correct spherical aberration and coma in the telephoto end state, which is not preferable.

By setting the upper limit value of conditional expression (26) to 1.50, the effect of embodiment 4 can be reliably obtained.

The variable magnification optical system ZL according to embodiment 4 preferably satisfies the following conditional expression (27).

1.00<|f33|/f3…(27)

Wherein the content of the first and second substances,

f 33: the focal length of the 33 rd lens group G33,

f 3: focal length of the 3 rd lens group G3.

The conditional expression (27) specifies an appropriate focal length of the 33 rd lens group G33 with respect to the focal length of the 3 rd lens group G3. Satisfying the conditional expression (27) enables to realize excellent optical performance and downsizing of the optical system.

If the value is less than the lower limit value of the conditional expression (27), the power of the 3 rd lens group G3 becomes weak, and it becomes difficult to downsize the lens barrel. When the powers of the 1 st lens group G1 and the 2 nd lens group G2 are strengthened for downsizing, it is difficult to correct coma, astigmatism, and field curvature, and therefore, such is not preferable.

By setting the lower limit value of conditional expression (27) to 2.00, the effect of embodiment 4 can be reliably obtained.

In the variable magnification optical system ZL of embodiment 4, the 32 nd lens group G32 is preferably formed of a single lens.

With this configuration, decentering coma and image plane variation in image blur correction can be corrected satisfactorily. In addition, the image shake correction mechanism can be miniaturized.

In the variable power optical system ZL according to embodiment 4, the 31 st lens group G31 preferably includes a front group G3F and a rear group G3R having positive refractive power arranged in this order from the object side, and focusing is performed by moving the front group G3F in the optical axis direction.

With this configuration, aberration variation (for example, spherical aberration) in focusing can be suppressed.

The variable magnification optical system ZL according to embodiment 4 preferably includes a stop S that moves in the optical axis direction integrally with the 3 rd lens group G3 during magnification change.

With this configuration, the lens barrel structure can be simplified and the lens barrel can be downsized.

The variable magnification optical system ZL according to embodiment 4 preferably includes a stop S disposed between the 2 nd lens group G2 and the image plane I.

With this configuration, the field curvature and the astigmatism can be corrected well.

The variable magnification optical system ZL according to embodiment 4 preferably satisfies the following conditional expression (28).

30.00°<ωw<80.00°…(28)

Wherein the content of the first and second substances,

ω w: half field angle in the wide-angle end state.

The conditional expression (28) is a condition for defining the value of the angle of view in the wide-angle end state. By satisfying this conditional expression (28), coma aberration, distortion, and field curvature can be corrected satisfactorily while having a wide angle of view.

By setting the lower limit value of conditional expression (28) to 33.00 °, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (28) to 36.00 °, further favorable aberration correction can be performed.

By setting the upper limit value of the conditional expression (28) to 77.00 °, more favorable aberration correction can be performed.

The variable magnification optical system ZL according to embodiment 4 preferably satisfies the following conditional expression (29).

2.00<ft/fw<15.00…(29)

Wherein the content of the first and second substances,

ft: the focal length of the entire system in the far-focus state,

fw: focal length of the entire system in the wide-angle end state.

The conditional expression (29) is a condition that specifies a ratio of the focal length of the entire system in the telephoto end state to the focal length of the entire system in the wide-angle end state. This variable magnification optical system ZL can obtain a high zoom ratio and can satisfactorily correct spherical aberration and coma aberration by satisfying conditional expression (29).

By setting the lower limit value of conditional expression (29) to 2.30, more favorable aberration correction can be performed. By setting the lower limit value of conditional expression (29) to 2.50, further favorable aberration correction can be performed. By setting the lower limit of conditional expression (29) to 2.70, the effect of embodiment 4 can be exhibited to the maximum.

By setting the upper limit value of conditional expression (29) to 10.00, more favorable aberration correction can be performed. By setting the upper limit value of conditional expression (29) to 7.00, further favorable aberration correction can be performed.

According to embodiment 4 described above, the variable magnification optical system ZL having high optical performance can be realized.

Next, a camera (imaging apparatus) 1 including the above-described variable magnification optical system ZL will be described with reference to fig. 17. The camera 1 is the same as the camera of embodiment 1, and the configuration thereof has already been described, and therefore, the description thereof is omitted here.

As will be understood from each of the examples described later, the variable magnification optical system ZL according to embodiment 4 mounted on the camera 1 as the photographing lens 2 has high optical performance due to its characteristic lens structure. Therefore, according to the camera 1, an image pickup apparatus having high optical performance can be realized.

Even when the zoom optical system ZL is mounted on a single-lens reflex type camera having a quick return mirror and observing an object through a finder optical system, the same effect as that of the camera 1 can be obtained. Even when the zoom optical system ZL is mounted on a video camera, the same effects as those of the camera 1 can be obtained.

Next, a method for manufacturing the variable magnification optical system ZL having the above-described configuration will be described in detail with reference to fig. 21. First, each lens is arranged in a lens barrel as follows: the present invention is provided with a 1 ST lens group G1 having positive refractive power, a 2 nd lens group G2 having negative refractive power, and a 3 rd lens group G3 having positive refractive power (step ST 410). At this time, each lens is arranged in the lens barrel as follows: when zooming is performed from the wide-angle end state to the telephoto end state, the 1 ST lens group G1 moves in the object direction along the optical axis direction (step ST 420). Further, each lens is arranged in the lens barrel so as to satisfy at least conditional expressions (23) and (24) of the above conditional expressions (step ST 430).

0.14<fw/f1<0.26…(23)

0.77<fw/f3<1.05…(24)

Wherein the content of the first and second substances,

fw: the focal length of the entire system in the wide-angle end state,

f 1: the focal length of the 1 st lens group G1,

f 3: focal length of the 3 rd lens group G3.

As shown in fig. 1, an example of the lens arrangement according to embodiment 4 is a cemented lens comprising, in order from the object side, a negative meniscus lens L11 with the convex surface facing the object side and a positive meniscus lens L12 with the convex surface facing the object side, as the 1 st lens group G1. In the 2 nd lens group G2, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 having a concave surface facing the object side are disposed in this order from the object side. In the 3 rd lens group G3, a positive meniscus lens L31 having a concave surface facing the object side, a cemented lens of a double convex lens L32 and a double concave lens L33, a double concave lens L34, a double convex lens L35, a double convex lens L36, and a negative meniscus lens L37 having a concave surface facing the object side are disposed in this order from the object side. Each lens is disposed so as to satisfy conditional expressions (23) and (24) (the corresponding value of conditional expression (23) is 0.22, and the corresponding value of conditional expression (24) is 0.90).

According to the method for manufacturing a variable magnification optical system of embodiment 4 described above, a variable magnification optical system ZL having high optical performance can be obtained.

Examples of embodiments 1 to 4

Next, examples of embodiments 1 to 4 will be described with reference to the drawings. Tables 1 to 4, which are tables of parameters in examples 1 to 4, are shown below.

Of these, example 4 corresponds only to embodiments 2 and 4.

Fig. 1, 5, 9 and 13 are sectional views showing the structures of the variable magnification optical systems ZL (ZL1 to ZL4) of the 1 st, 2 nd, 3 rd and 4 th embodiments, respectively. In cross-sectional views of the variable power optical systems ZL1 to ZL4, movement loci of the respective lens groups along the optical axis when performing variable power from the wide-angle end state (W) to the telephoto end state (T) are shown by arrows.

The reference numerals in fig. 1 of embodiment 1 are used independently for each embodiment in order to avoid complication of the description due to an increase in the number of digits of the reference numerals. Therefore, even if reference numerals are attached to the drawings of the other embodiments, they do not necessarily have the same structure as the other embodiments.

In each example, a d-line (wavelength 587.5620nm) and a g-line (wavelength 435.8350nm) were selected as targets for calculating aberration characteristics.

In the table [ lens data ], a surface number indicates the order of optical surfaces from the object side along the direction in which light travels, r indicates the radius of curvature of each optical surface, D indicates the distance on the optical axis from each optical surface to the next optical surface (or image surface), i.e., the surface distance, vd indicates the abbe number of the material of the optical member with respect to the D-line as a reference, and nd indicates the refractive index of the material of the optical member with respect to the D-line. (variable) denotes a variable plane spacing, "∞" of the radius of curvature denotes a plane or an opening, (stop S) denotes an aperture stop S. The refractive index of air (d line) "1.000000" was omitted. When the optical surface is an aspherical surface, the left side of the surface number is marked with "+" and the paraxial radius of curvature is shown in the column of radius of curvature r.

In table [ aspherical data ]]In relation to [ lens data ]]The aspherical surface shown in (a) shows the shape thereof by the following expression (a). Here, y represents a height in a direction perpendicular to the optical axis, x (y) represents a displacement amount (depression amount) in the optical axis direction at the height y, r represents a curvature radius (paraxial curvature radius) of the reference spherical surface, κ represents a conic constant, and An represents An aspherical coefficient of the nth order. Further, "E-n" represents ". times.10^-n", for example," 1.234E-05 "means" 1.234X 10^-5”。

X(y)＝(y²/r)/[1+{1-κ(y²/r²)}^1/2]+A4×y⁴+A6×y⁶+A8×y⁸+A10×y¹⁰…(a)

In [ various data ] in the table, F denotes a focal length of the entire lens system, Fno denotes an F value, ω denotes a half field angle (unit: °), Y denotes an image height, TL denotes a total length of the lens system (distance from the foremost lens to the image plane I on the optical axis), and Bf denotes a back focal length (distance from the final lens plane to the image plane I on the optical axis).

In [ variable interval data ] in the table, the focal length f or the photographing magnification β of the entire system and the values of the respective variable intervals in the wide-angle end state, the intermediate focal length state, and the far-focus end state when focusing on an infinite object and a short-distance object (photographing distance R is 1.0m) are shown. D0 represents the distance from the object surface to the 1 st surface, and Di (where i is an integer) represents the variable distance between the i-th surface and the (i +1) -th surface.

In [ lens group data ] in the table, the initial surface number (surface number closest to the object side) of each group is shown in the group initial surface, and the focal length of each group is shown in the group focal length.

In the table, "values corresponding to conditional expressions" show values corresponding to the conditional expressions (1) to (29) described above.

In the following, although "mm" is generally used for all the disclosed focal length f, curvature radius R, surface distance D, other lengths, and the like, in all the parameter values, the optical performance can be obtained even if the optical system is scaled up or down, and thus the present invention is not limited thereto. The unit is not limited to "mm", and other appropriate units can be used.

The above table is explained in the same manner in all the examples, and the following explanation is omitted.

(embodiment 1)

Embodiment 1 will be described with reference to fig. 1 to 4 and table 1. As shown in fig. 1, the variable power optical system ZL (ZL1) of example 1 is composed of a 1 st lens group G1 having positive power, a 2 nd lens group G2 having negative power, and a 3 rd lens group G3 having positive power, which are arranged in this order from the object side along the optical axis.

The 1 st lens group G1 is composed of a cemented lens of a negative meniscus lens L11 with a convex surface facing the object side and a positive meniscus lens L12 with a convex surface facing the object side, which are arranged in this order from the object side.

The 2 nd lens group G2 is composed of, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a negative meniscus lens L24 with a concave surface facing the object side.

The 3 rd lens group G3 is composed of, in order from the object side, a 31 st lens group G31, a 32 nd lens group G32, and a 33 rd lens group G33.

The 31 st lens group G31 is composed of a front group G3F and a rear group G3R having positive optical power, which are arranged in order from the object side. The front group G3F (focus group) is constituted by a positive meniscus lens L31 with the concave surface facing the object side. The rear group G3R is composed of a cemented lens of a biconvex lens L32 and a biconcave lens L33 arranged in this order from the object side.

The 32 nd lens group G32 (anti-shake lens group) is composed of a biconcave lens L34. The 33 rd lens group G33 is composed of, in order from the object side, a biconvex lens L35, a biconvex lens L36, and a negative meniscus lens L37 with its concave surface facing the object side.

An aperture stop S that determines the F value is provided in the 3 rd lens group G3.

The image plane I is formed on an image pickup device, not shown, which is formed of a CCD, a CMOS, or the like.