JP2023001329A - Zoom optical system and optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom optical system capable of suppressing variation of aberrations in zooming or focusing.

SOLUTION: A zoom optical system ZL provided herein comprises a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a succeeding lens group GR, which are arranged in order from an object side. The succeeding lens group GR comprises a fifth lens group G5 and a sixth lens group G6 arranged in order form the object side, and is configured such that the distance between the adjacent lens groups changes in zooming. The succeeding lens group GR includes a focusing lens group configured to move in focusing, and the focusing lens group is located closer to an image side than an aperture stop S. The first lens group G1 consists of a first lens L11 having negative refractive power, a second lens L12 having positive refractive power, and a third lens L13 having positive refractive power arranged in order from the object side. The third lens group G3 consists of one or more lenses having positive refractive power.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a variable power optical system and an optical apparatus using the same.

2. Description of the Related Art Conventionally, variable-magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras, etc. have been proposed (see, for example, Patent Document 1). In a variable power optical system, it is required to suppress fluctuations in aberration during variable power or focusing.

JP 2013-160944 A

A variable power optical system according to a first aspect comprises a first lens group having positive refractive power, a second lens group having negative refractive power, and a second lens group having positive refractive power, which are arranged in order from the object side. It has three lens groups, a fourth lens group having positive refractive power, and a subsequent lens group, wherein the subsequent lens group comprises a fifth lens group and a sixth lens group arranged in order from the object side. wherein the distance between adjacent lens groups changes during zooming, the succeeding lens group comprises a focusing lens group that moves during focusing, the focusing lens group comprising an aperture stop The first lens group includes a first lens having negative refractive power, a second lens having positive refractive power, and a positive refractive power arranged in order from the object side. and the third lens group has one or more positive refractive power including a single lens having positive refractive power disposed closest to the object side of the third lens group and satisfies the following conditional expression:
0.20<f3/f4<2.50
where f3: focal length of the third lens group f4: focal length of the fourth lens group

An optical apparatus according to a second aspect is configured by mounting the variable power optical system.

1 is a diagram showing a lens configuration of a variable power optical system according to a first example; FIG. 2(A), 2(B), and 2(C) show the zoom optical system according to the first embodiment when focusing on infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 3(A), 3(B), and 3(C) respectively show the zooming optical system according to the first embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations. FIG. 10 is a diagram showing a lens configuration of a variable-magnification optical system according to a second example; 5(A), 5(B), and 5(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the second embodiment, respectively, when focusing on infinity. is a diagram of various aberrations. 6(A), 6(B), and 6(C) respectively show the zooming optical system according to the second embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a third example; 8(A), 8(B), and 8(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the third embodiment, respectively, when focusing on infinity. is a diagram of various aberrations. 9(A), 9(B), and 9(C) show the close-distance focusing in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the third embodiment, respectively. is a diagram of various aberrations. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a fourth example; 11(A), 11(B), and 11(C) show the zoom lens system according to the fourth embodiment when focusing on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. is a diagram of various aberrations. 12(A), 12(B), and 12(C) respectively show the zooming optical system according to the fourth embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a fifth example; 14(A), 14(B), and 14(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the fifth embodiment, respectively, when focusing at infinity. is a diagram of various aberrations. 15(A), 15(B), and 15(C) show the zoom optical system according to the fifth embodiment when focusing at a short distance in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. is a diagram of various aberrations. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a sixth example; 17(A), 17(B), and 17(C) show the zoom optical system according to the sixth embodiment when focusing at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 18(A), 18(B), and 18(C) show the zoom optical system according to the sixth embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively, when focusing at a short distance. is a diagram of various aberrations. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a seventh example; 20(A), 20(B), and 20(C) show the zoom optical system according to the seventh embodiment when focusing on infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 21(A), 21(B), and 21(C) respectively show the zooming optical system according to the seventh embodiment at the time of close-distance focusing in the wide-angle end state, the intermediate focal length state, and the telephoto end state. is a diagram of various aberrations. 1 is a diagram showing the configuration of a camera equipped with a variable magnification optical system according to this embodiment; FIG. 4 is a flow chart showing a method for manufacturing a variable magnification optical system according to the present embodiment;

A variable magnification optical system and an optical apparatus according to the present embodiment will be described below with reference to the drawings. First, a camera (optical device) having a variable power optical system according to this embodiment will be described with reference to FIG. This camera 1 is a digital camera provided with a variable-magnification optical system according to the present embodiment as a photographing lens 2, as shown in FIG. In the camera 1 , light from an object (subject) (not shown) is condensed by the photographing lens 2 and reaches the imaging device 3 . As a result, the light from the subject is imaged by the imaging element 3 and recorded in a memory (not shown) as an image of the subject. In this manner, the photographer can photograph the subject with the camera 1. FIG. This camera may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror.

Next, a variable magnification optical system (taking lens) according to this embodiment will be described. As shown in FIG. 1, a variable power optical system ZL(1) as an example of a variable power optical system (zoom lens) ZL according to the present embodiment includes first lenses having positive refractive power arranged in order from the object side. A lens group G1, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and a subsequent lens group GR. It is configured so that the distance between adjacent lens groups changes during zooming. The trailing lens group GR has a focusing lens group that moves during focusing. The third lens group G3 is composed of at least one lens having positive refractive power.

The variable-magnification optical system ZL according to this embodiment has at least five lens groups, and the distance between the lens groups changes when the magnification is varied. As a result, according to the present embodiment, it is possible to suppress fluctuations in aberration during zooming from the wide-angle end state to the telephoto end state. In addition, by arranging the focusing lens group in the rear lens group GR, it is possible to reduce the size and weight of the focusing lens group. becomes possible. Further, since the third lens group G3 is composed of lenses having positive refractive power, it is possible to correct spherical aberration in the telephoto end state without increasing the size of the lens barrel.

The variable power optical system ZL according to this embodiment may be the variable power optical system ZL(2) shown in FIG. 4, the variable power optical system ZL(3) shown in FIG. 7, or the variable power optical system shown in FIG. It may be ZL(4). Further, the variable-magnification optical system ZL according to the present embodiment may be the variable-magnification optical system ZL(5) shown in FIG. 13, the variable-magnification optical system ZL(6) shown in FIG. It may be the optical system ZL(7).

With the above configuration, the variable power optical system ZL according to this embodiment satisfies the following conditional expression (1).

0.20<f3/f4<2.50 (1)
However, f3: the focal length of the third lens group G3 f4: the focal length of the fourth lens group G4

Conditional expression (1) defines the ratio between the focal length of the third lens group G3 and the focal length of the fourth lens group G4. Satisfying conditional expression (1) makes it possible to suppress variations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the corresponding value of conditional expression (1) exceeds the upper limit, the refractive power of the fourth lens group G4 becomes too strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. Become. By setting the upper limit of conditional expression (1) to 2.40, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (1) is set to 2.30, 2.20, 2.10, 2.00, 1.90, 1.80, 1 It may be set to 0.50, 1.30, 1.00 or even 0.90.

If the corresponding value of conditional expression (1) falls below the lower limit, the refractive power of the third lens group G3 becomes too strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. Become. By setting the lower limit of conditional expression (1) to 0.22, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (1) is set to 0.25, 0.28, 0.30, 0.31, 0.32, 0.33, and further to It may be set to 0.34.

In the variable power optical system ZL according to this embodiment, the third lens group G3 is composed of a 31st lens having positive refractive power and a 32nd lens having positive refractive power, which are arranged in order from the object side. is desirable. This makes it possible to satisfactorily correct spherical aberration in the telephoto end state without increasing the size of the lens barrel.

In the variable power optical system ZL according to this embodiment, the first lens group G1 has an eleventh lens having negative refractive power and a twelfth lens having positive refractive power, which are arranged in order from the object side. , it is desirable to satisfy the following conditional expression (2).

0.010<dP1/f1<0.075 (2)
where dP1 is the sum of the center thickness of the 11th lens and the center thickness of the 12th lens f1 is the focal length of the first lens group G1

Conditional expression (2) defines the ratio between the sum of the center thickness of the 11th lens and the center thickness of the 12th lens and the focal length of the first lens group G1. By satisfying conditional expression (2), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the corresponding value of conditional expression (2) exceeds the upper limit, the refractive power of the first lens group G1 becomes too strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. Become. By setting the upper limit of conditional expression (2) to 0.074, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (2) is set to 0.072, 0.070, 0.069, 0.068, 0.067, and further to 0.066. May be set.

If the corresponding value of conditional expression (2) is below the lower limit, the refractive power of the first lens group G1 becomes too weak, resulting in an increase in the size of the lens barrel. In addition, it becomes difficult to suppress variations in various aberrations including spherical aberration during zooming. By setting the lower limit of conditional expression (2) to 0.015, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (2) is set to 0.020, 0.025, 0.030, 0.033, 0.035, 0.038, and further to It may be set to 0.040.

In the variable magnification optical system ZL according to this embodiment, it is desirable that the focusing lens group consist of three or less single lenses. As a result, the size and weight of the focusing lens group can be reduced.

In the variable magnification optical system ZL according to this embodiment, it is desirable that at least one of the focusing lens groups has a single lens with negative refractive power. This makes it possible to suppress fluctuations in various aberrations including spherical aberration when focusing from an object at infinity to an object at close range.

In the variable-magnification optical system ZL according to this embodiment, it is desirable that the focusing lens group be arranged closer to the image side than the aperture stop S. As a result, the size and weight of the focusing lens group can be reduced.

In the variable-magnification optical system ZL according to this embodiment, it is desirable that at least four lens groups be arranged on the image side of the aperture stop S. This makes it possible to suppress variations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

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

0.20<|fF|/ft<4.00 (3)
However, fF: the focal length of the focusing lens group with the strongest refractive power among the focusing lens groups, ft: the focal length of the variable power optical system ZL in the telephoto end state.

Conditional expression (3) defines the ratio between the focal length of the focusing lens group having the strongest refractive power and the focal length of the variable magnification optical system ZL in the telephoto end state. Satisfying conditional expression (3) makes it possible to suppress variations in various aberrations including spherical aberration when focusing from an object at infinity to an object at close range without increasing the size of the lens barrel.

If the corresponding value of conditional expression (3) exceeds the upper limit, the refractive power of the focusing lens group becomes too weak, so the amount of movement of the focusing lens group during focusing increases, and the size of the lens barrel increases. . By setting the upper limit of conditional expression (3) to 3.80, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (3) is set to 3.60, 3.40, 3.20, 3.00, 2.80, 2.60, 2 .40, 2.20, or even 2.00.

If the corresponding value of conditional expression (3) is below the lower limit, the refractive power of the focusing lens group becomes too strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during focusing. . By setting the lower limit of conditional expression (3) to 0.23, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (3) may be set to 0.25, 0.28, 0.30, 0.33, or even 0.35. good.

In the variable magnification optical system ZL according to this embodiment, it is desirable that the fourth lens group G4 has a cemented lens composed of a negative lens and a positive lens. This makes it possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

In the variable power optical system ZL according to this embodiment, the fourth lens group G4 preferably has a cemented lens composed of a negative lens and a positive lens, and satisfies the following conditional expression (4).

1.00<nN/nP<1.35 (4)
where nN: refractive index of the negative lens in the cemented lens nP: refractive index of the positive lens in the cemented lens

Conditional expression (4) defines the ratio between the refractive index of the negative lens and the refractive index of the positive lens in the cemented lens in the fourth lens group G4. By satisfying conditional expression (4), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the corresponding value of conditional expression (4) exceeds the upper limit, the refracting power of the negative lens in the cemented lens becomes too strong, resulting in excessive correction of spherical aberration in the telephoto end state, and from the wide-angle end state to the telephoto end state. It becomes difficult to suppress variations in various aberrations including spherical aberration during zooming. By setting the upper limit of conditional expression (4) to 1.33, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (4) is set to 1.30, 1.29, 1.28, 1.27, 1.26, and further to 1.25. May be set.

If the corresponding value of conditional expression (4) is less than the lower limit, the refractive power of the negative lens in the cemented lens becomes too weak, and as a result, correction of spherical aberration in the telephoto end state becomes insufficient, resulting in a transition from the wide-angle end state to the telephoto end state. It becomes difficult to suppress variations in various aberrations including spherical aberration during zooming. By setting the lower limit of conditional expression (4) to 1.02, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (4) is set to 1.05, 1.08, 1.10, 1.11, 1.12, 1.13, 1 .14, 1.15.

In the variable magnification optical system ZL according to this embodiment, the fourth lens group G4 preferably has a cemented lens composed of a negative lens and a positive lens, and satisfies the following conditional expression (5).

0.20<νN/νP<0.85 (5)
where νN: Abbe number of the negative lens in the cemented lens νP: Abbe number of the positive lens in the cemented lens

Conditional expression (5) defines the ratio between the Abbe number of the negative lens and the Abbe number of the positive lens in the cemented lens in the fourth lens group G4. By satisfying conditional expression (5), it is possible to satisfactorily correct chromatic aberration.

When the corresponding value of conditional expression (5) exceeds the upper limit, the Abbe number of the positive lens in the cemented lens becomes small, so that chromatic aberration occurs excessively, making it difficult to correct chromatic aberration. By setting the upper limit of conditional expression (5) to 0.83, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (5) is set to 0.80, 0.78, 0.75, 0.73, 0.70, 0.68, 0. It may be set to 0.65, 0.63, 0.60, 0.58, 0.55, 0.53 and even 0.50.

If the corresponding value of conditional expression (5) is below the lower limit, the Abbe number of the negative lens in the cemented lens becomes small, resulting in excessive correction of chromatic aberration. By setting the lower limit of conditional expression (5) to 0.22, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (5) is set to 0.24, 0.25, 0.26, 0.27, 0.28, and further to 0.29. May be set.

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

f1/|fRw|<5.00 (6)
where f1: focal length of the first lens group G1 fRw: focal length of the subsequent lens group GR in the wide-angle end state

Conditional expression (6) defines the ratio between the focal length of the first lens group G1 and the focal length of the subsequent lens group GR in the wide-angle end state. By satisfying conditional expression (6), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the corresponding value of conditional expression (6) exceeds the upper limit, the refractive power of the subsequent lens group GR becomes too strong, making it difficult to suppress fluctuations in various aberrations including spherical aberration during zooming. . By setting the upper limit of conditional expression (6) to 4.80, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (6) is set to 4.60, 4.40, 4.20, 4.00, 3.80, 3.50, 3 .00, 2.80, 2.50, 2.30, 2.00, 1.80, or even 1.50.

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

2ωw>75° (7)
where ωw is the half angle of view of the variable magnification optical system ZL in the wide-angle end state

Conditional expression (7) defines the half angle of view of the variable magnification optical system ZL in the wide-angle end state. By satisfying the conditional expression (7), it is possible to suppress fluctuations in aberration during zooming from the wide-angle end state to the telephoto end state while maintaining a wide angle of view. By setting the lower limit of conditional expression (7) to 76°, the effect of the present embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (7) may be set to 77°, 78°, 79°, 80°, 81°, or even 82°.

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

0.10<BFw/fw<1.00 (8)
where BFw: back focus of variable-magnification optical system ZL in wide-angle end state fw: focal length of variable-magnification optical system ZL in wide-angle end state

Conditional expression (8) defines the ratio between the back focus of the variable power optical system ZL in the wide-angle end state and the focal length of the variable power optical system ZL in the wide-angle end state. By satisfying the conditional expression (8), it is possible to satisfactorily correct various aberrations including coma in the wide-angle end state.

If the corresponding value of conditional expression (8) exceeds the upper limit, the back focus becomes too large with respect to the focal length of the variable magnification optical system ZL in the wide-angle end state, and various aberrations including coma in the wide-angle end state. becomes difficult to correct. By setting the upper limit of conditional expression (8) to 0.95, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (8) is set to 0.90, 0.85, 0.80, 0.78, 0.75, 0.73, 0. It may be set to 0.70, 0.68, or even 0.65.

If the corresponding value of conditional expression (8) is below the lower limit, the back focal length becomes too small with respect to the focal length of the variable power optical system ZL in the wide-angle end state. becomes difficult to correct. In addition, it becomes difficult to arrange the mechanical members of the lens barrel. By setting the lower limit of conditional expression (8) to 0.15, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (8) is set to 0.20, 0.25, 0.30, 0.35, 0.37, 0.38, 0. It may be set to 0.40, 0.42, 0.44, or even 0.45.

In the variable-magnification optical system ZL according to this embodiment, when the focusing lens group has positive refractive power, it is desirable to satisfy the following conditional expression (9).

0.00<(rR2+rR1)/(rR2-rR1)<8.00 (9)
where rR1 is the radius of curvature of the object-side lens surface of the lens closest to the image side in the variable-magnification optical system ZL, rR2 is the radius of curvature of the image-side lens surface of the lens closest to the image side of the variable-magnification optical system ZL. curvature radius

Conditional expression (9) defines the shape factor of the lens arranged closest to the image side of the variable magnification optical system ZL. By satisfying conditional expression (9), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the corresponding value of conditional expression (9) exceeds the upper limit, the coma aberration correction power of the lens closest to the image side of the variable-magnification optical system ZL will be insufficient. difficult to suppress. By setting the upper limit of conditional expression (9) to 7.50, the effect of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (9) is set to 7.00, 6.80, 6.50, 6.30, 6.00, 5.80, 5 It may be set to .50, 5.30, or even 5.00.

If the corresponding value of conditional expression (9) is below the lower limit, the lens located closest to the image side in the variable magnification optical system ZL will have insufficient coma aberration correction power. difficult to suppress. By setting the lower limit of conditional expression (9) to 0.10, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (9) is set to 0.50, 0.80, 1.00, 1.20, 1.50, 1.80, 2 .00, 2.20, or even 2.50.

In the variable-magnification optical system ZL according to this embodiment, when the focusing lens group has negative refractive power, it is desirable to satisfy the following conditional expression (10).

−4.00<(rR2+rR1)/(rR2−rR1)<4.00 (10)
where rR1 is the radius of curvature of the object-side lens surface of the lens closest to the image side in the variable-magnification optical system ZL, rR2 is the radius of curvature of the image-side lens surface of the lens closest to the image side of the variable-magnification optical system ZL. curvature radius

Conditional expression (10) defines the shape factor of the lens arranged closest to the image side of the variable magnification optical system ZL. By satisfying conditional expression (10), it is possible to suppress fluctuations in various aberrations including spherical aberration during zooming from the wide-angle end state to the telephoto end state.

If the corresponding value of conditional expression (10) exceeds the upper limit, the coma aberration correction power of the lens closest to the image side of the variable-magnification optical system ZL is insufficient. difficult to suppress. By setting the upper limit of conditional expression (10) to 3.80, the effects of this embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the upper limit of conditional expression (10) is set to 3.50, 3.30, 3.00, 2.80, 2.50, 2.30, 2 It may be set to .00, 1.80, or even 1.50.

If the corresponding value of conditional expression (10) is below the lower limit, the lens located closest to the image side in the variable magnification optical system ZL will have insufficient coma aberration correction power. difficult to suppress. By setting the lower limit of conditional expression (10) to −3.80, the effects of the present embodiment can be made more reliable. In order to further ensure the effect of this embodiment, the lower limit of conditional expression (10) is set to -3.50, -3.30, -3.00, -2.80, -2.50, You can set it to -2.30, -2.00, -1.80, or even -1.50.

Next, a method for manufacturing the variable power optical system ZL according to this embodiment will be outlined with reference to FIG. First, from the object side, the first lens group G1 having positive refractive power, the second lens group G2 having negative refractive power, the third lens group G3 having positive refractive power, and the positive refractive power and the subsequent lens group GR (step ST1). Then, when the magnification is changed, the distance between the adjacent lens groups is changed (step ST2). Also, a focusing lens group that moves during focusing is arranged in the rear lens group GR, and at least one lens having a positive refractive power is arranged in the third lens group G3 (step ST3). Further, each lens is arranged in the lens barrel so as to satisfy at least conditional expression (1) (step ST4). According to such a manufacturing method, it is possible to achieve high-speed and quiet autofocus without increasing the size of the lens barrel. It is possible to manufacture a variable-magnification optical system that suppresses fluctuations in aberration when focusing from an object at infinity to an object at a short distance.

The variable magnification optical system ZL according to each embodiment will be described below with reference to the drawings. 1, 4, 7, 10, 13, 16, and 19 show the configurations and FIG. 4 is a cross-sectional view showing refractive power distribution; The first to seventh examples are examples corresponding to this embodiment. In each cross-sectional view, an arrow indicates the moving direction of each lens group along the optical axis when zooming from the wide-angle end state (W) to the telephoto end state (T). Further, the direction of movement of the focusing lens group when focusing on a close object from infinity is indicated by an arrow together with the word "focus".

In these figures (FIGS. 1, 4, 7, 10, 13, 16 and 19), each lens group is represented by a combination of symbol G and a number, and each lens is represented by a combination of symbol L and a number. represent each. In this case, in order to prevent complication due to a large number of types and numbers of symbols and numerals, the lens groups and the like are represented independently using combinations of symbols and numerals for each embodiment. Therefore, even if the same reference numerals and symbols are used between the embodiments, it does not mean that they have the same configuration.

Tables 1 to 7 are shown below, of which Table 1 is the first embodiment, Table 2 is the second embodiment, Table 3 is the third embodiment, Table 4 is the fourth embodiment, and Table 5 is the third embodiment. Table 6 is a table showing each specification data in the fifth embodiment, Table 6 is the sixth embodiment, and Table 7 is the seventh embodiment. In each embodiment, the d-line (wavelength λ=587.6 nm) and the g-line (wavelength λ=435.8 nm) are selected as objects for calculating aberration characteristics.

In the [Overall specifications] table, f is the focal length of the entire lens system, FNO is the F number, 2ω is the angle of view (unit is ° (degrees), ω is the half angle of view), and Ymax is the maximum image height. indicates TL indicates the distance obtained by adding BF to the distance from the foremost lens surface to the last lens surface on the optical axis when focusing on infinity, and BF is the distance from the last lens surface on the optical axis when focusing on infinity. The air conversion distance (back focus) to plane I is shown. Note that these values are shown for each of the zooming states of the wide-angle end (W), the intermediate focal length (M), and the telephoto end (T). In the [Overall Specifications] table, fRw indicates the focal length of the subsequent lens group in the wide-angle end state.

In the [Lens Specifications] table, the surface number indicates the order of the optical surfaces from the object side along the direction in which light rays travel, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image side). is a positive value), D is the distance on the optical axis from each optical surface to the next optical surface (or image plane), nd is the refractive index of the material of the optical member for the d-line, and νd is the optical The Abbe numbers of the materials of the members with respect to the d-line are shown. The radius of curvature “∞” indicates a plane or an aperture, and (stop S) indicates an aperture stop. The description of the refractive index of air nd=1.00000 is omitted. When the lens surface is an aspherical surface, the surface number is marked with an asterisk (*), and the column of curvature radius R indicates the paraxial curvature radius.

In the table of [aspheric surface data], the shape of the aspheric surface shown in [lens specifications] is shown by the following equation (A). X(y) is the distance (zag amount) along the optical axis from the tangent plane at the vertex of the aspherical surface to the position on the aspherical surface at height y, and R is the radius of curvature of the reference sphere (paraxial radius of curvature) , κ is the conic constant, and Ai is the i-th order aspheric coefficient. “E-n” indicates “×10 ⁻ⁿ ”. For example, 1.234E-05 = 1.234 x ^10-5 . Note that the second-order aspheric coefficient A2 is 0, and its description is omitted.

^X (y) ⁼ (y2/R)/{1+( ¹ -κ×y2/ ^R2 ) ^1/2 }+A4× ^y4 +A6× ^y6 +A8× ^y8 +A10×y10+A12× ^y12・... (A)

The [Lens Group Data] table shows the starting surface (surface closest to the object side) and focal length of each lens group.

The [Variable Spacing Data] table shows the surface spacing of the surface numbers for which the surface spacing is "variable" in the [Lens Specifications] table. Shown here are the surface distances at the wide-angle end (W), the intermediate focal length (M), and the telephoto end (T), respectively, when the lens is focused on infinity and on a short distance.

The [value corresponding to conditional expression] table shows the value corresponding to each conditional expression.

Unless otherwise specified, "mm" is generally used for the focal length f, radius of curvature R, surface spacing D, and other lengths in all specifications below, but the optical system is proportionally enlarged. Alternatively, it is not limited to this because equivalent optical performance can be obtained even if it is proportionally reduced.

The description of the table up to this point is common to all the embodiments, and redundant description will be omitted below.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 to 3 and Table 1. FIG. FIG. 1 is a diagram showing the lens configuration of a variable magnification optical system according to the first embodiment. The variable power optical system ZL(1) according to the first example includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a third lens group G5 having positive refractive power. It consists of 6 lens groups G6 and a 7th lens group G7 having negative refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the subsequent lens group GR, and has negative refractive power as a whole. The sign (+) or (-) attached to each lens group symbol indicates the refractive power of each lens group, and this is the same for all the following examples.

The first lens group G1 includes a positive lens cemented with a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side, and a positive lens having a convex surface facing the object side. and a positive meniscus lens L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive meniscus lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a concave surface on the object side. and a negative meniscus lens L24. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive meniscus lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 is composed of a cemented positive lens constructed by cementing a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42.

The fifth lens group G5 is composed of, in order from the object side, a negative meniscus lens L51 having a concave surface facing the object side and a biconvex positive lens L52.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side. The positive meniscus lens L61 has an aspheric lens surface on the image side.

The seventh lens group G7 is composed of, in order from the object side, a positive meniscus lens L71 with a concave surface facing the object side, a biconcave negative lens L72, and a negative meniscus lens L73 with a concave surface facing the object side. be done. The negative lens L72 has an aspheric lens surface on the object side. An image plane I is arranged on the image side of the seventh lens group G7.

In this embodiment, by independently moving the fifth lens group G5 and the sixth lens group G6 toward the object side, focusing from a long distance object to a short distance object (from an infinite distance object to a finite distance object) can be performed. done. That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

Table 1 below lists values of specifications of the variable-magnification optical system according to the first example.

(Table 1)
[Overall specifications]
Zoom ratio 2.74
fRw = -4993.677
WMT
f 24.8 50.0 67.9
FNO 2.92 2.92 2.92
2ω 85.10 45.26 33.84
Ymax 21.60 21.60 21.60
TL 139.35 158.45 169.16
BF 11.93 23.42 28.62
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 234.3873 2.500 1.84666 23.80
2 109.5180 5.200 1.75500 52.34
3 389.6852 0.200
4 59.0627 5.700 1.77250 49.62
5 135.3649 D5 (variable)
6* 218.4420 2.000 1.74389 49.53
7 18.6957 9.658
8 -59.6856 1.300 1.77250 49.62
9 59.6856 0.442
10 39.2099 6.400 1.72825 28.38
11 -48.6731 1.933
12 -26.4065 1.300 1.61800 63.34
13 -71.7612 D13 (Variable)
14 ∞ 1.712 (Aperture S)
15* 71.8876 2.500 1.69370 53.32
16 127.6411 0.716
17 38.7492 5.900 1.59319 67.90
18 -105.4274 D18 (Variable)
19 67.0276 1.300 1.73800 32.33
20 19.5126 9.700 1.49782 82.57
21 -50.5609 D21 (Variable)
22 -23.9237 1.200 1.72047 34.71
23 -56.2081 0.200
24 103.1749 5.900 1.59349 67.00
25 -33.0197 D25 (Variable)
26 -70.6288 3.500 1.79189 45.04
27* -38.2153 D27 (variable)
28 -43.9824 3.000 1.94595 17.98
29 -32.4253 0.200
30* -100.5837 1.500 1.85207 40.15
31 88.1634 7.847
32 -25.2838 1.400 1.58913 61.22
33-45.3661 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4=5.27866E-06, A6=-5.41835E-09
A8=1.33113E-11, A10=-2.04736E-14, A12=2.05090E-17
15th surface κ=1.0000, A4=-4.55747E-06, A6=-1.40092E-10
A8=-8.81384E-13, A10=-8.42653E-15, A12=0.00000E+00
27th surface κ=1.0000, A4=1.09543E-05, A6=-2.36281E-08
A8=1.42728E-10, A10=-5.02724E-13, A12=7.51800E-16
30th surface κ=1.0000, A4=-2.18913E-06, A6=-2.29301E-08
A8=3.94582E-11, A10=-9.84200E-14, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 119.124
G2 6 -22.126
G3 14 40.880
G4 19 115.687
G5 22 124.717
G6 26 100.365
G7 28-47.354
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 1.780 21.220 30.246 1.780 21.220 30.246
D13 19.285 6.132 2.013 19.285 6.132 2.013
D18 9.167 3.866 1.493 9.167 3.866 1.493
D21 5.179 14.279 19.018 4.137 12.991 17.666
D25 2.679 3.515 2.616 3.249 4.079 3.027
D27 6.128 2.807 1.953 6.600 3.530 2.893
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=0.353
Conditional expression (2) dP1/f1=0.065
Conditional expression (3) |fF|/ft=1.837
Conditional expression (4) nN/nP = 1.160
Conditional expression (5) νN/νP = 0.392
Conditional expression (6) f1/|fRw|=0.024
Conditional expression (7) 2ωw=85.10
Conditional expression (8) BFw/fw=0.482
Conditional expression (9) (rR2+rR1)/(rR2-rR1)=3.518

2(A), 2(B), and 2(C) show the zoom optical system according to the first embodiment when focusing on infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 3(A), 3(B), and 3(C) respectively show the zooming optical system according to the first embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations.

In the aberration diagrams of FIGS. 2A to 2C, FNO indicates the F number and Y indicates the image height. The spherical aberration diagram shows the F-number value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the lateral aberration diagram shows the value of each image height. In the aberration diagrams of FIGS. 3A to 3C, NA indicates the numerical aperture and Y indicates the image height. The spherical aberration diagram shows the numerical aperture value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the lateral aberration diagram shows the value of each image height. In each aberration diagram, d indicates d-line (wavelength λ=587.6 nm) and g indicates g-line (wavelength λ=435.8 nm). In the astigmatism diagrams, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. In the aberration diagrams of each example shown below, the same reference numerals as in the present example are used, and redundant description is omitted.

From the various aberration diagrams, it can be seen that the variable magnification optical system according to the first example has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 4 to 6 and Table 2. FIG. FIG. 4 is a diagram showing the lens configuration of the variable power optical system according to the second embodiment. A variable magnification optical system ZL(2) according to the second embodiment includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a third lens group G5 having positive refractive power. It consists of 6 lens groups G6 and a 7th lens group G7 having negative refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the subsequent lens group GR, and has negative refractive power as a whole.

The first lens group G1 includes a positive lens cemented with a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side, and a positive lens having a convex surface facing the object side. and a positive meniscus lens L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive meniscus lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a concave surface on the object side. and a negative meniscus lens L24. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of a biconvex positive lens L31 and a biconvex positive lens L32, which are arranged in order from the object side. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 is composed of a cemented positive lens constructed by cementing a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42.

The fifth lens group G5 is composed of, in order from the object side, a negative meniscus lens L51 having a concave surface facing the object side and a biconvex positive lens L52.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side. The positive meniscus lens L61 has an aspheric lens surface on the image side.

The seventh lens group G7 is composed of, in order from the object side, a positive meniscus lens L71 with a concave surface facing the object side, a biconcave negative lens L72, and a negative meniscus lens L73 with a concave surface facing the object side. be done. The negative lens L72 has an aspheric lens surface on the object side. An image plane I is arranged on the image side of the seventh lens group G7.

In this embodiment, by independently moving the fifth lens group G5 and the sixth lens group G6 toward the object side, focusing from a long distance object to a short distance object (from an infinite distance object to a finite distance object) can be performed. done. That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

Table 2 below lists values of specifications of the variable-magnification optical system according to the second example.

(Table 2)
[Overall specifications]
Zoom ratio 2.74
fRw = -346.533
WMT
f 24.8 50.0 67.9
FNO 2.92 2.92 2.92
2ω 85.08 45.32 33.84
Ymax 21.60 21.60 21.60
TL 139.96 156.15 168.00
BF 11.76 26.07 29.33
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 282.3733 2.500 1.84666 23.80
2 123.2365 5.647 1.77250 49.62
3 1180.1775 0.200
4 59.2907 4.310 1.81600 46.59
5 98.9987 D5 (variable)
6* 205.3191 2.000 1.74389 49.53
7 19.2200 9.185
8 -74.7032 1.300 1.83481 42.73
9 64.3697 0.324
10 41.9771 5.683 1.78472 25.64
11 -72.0408 4.071
12 -26.6709 1.300 1.60300 65.44
13 -52.5345 D13 (Variable)
14 ∞ 1.500 (Aperture S)
15* 84.6431 3.039 1.58913 61.15
16 -4073.6051 0.200
17 42.4140 5.438 1.59319 67.90
18 -143.7473 D18 (Variable)
19 74.9775 1.300 1.73800 32.33
20 20.9860 9.090 1.49782 82.57
21 -48.9247 D21 (Variable)
22 -23.9603 1.200 1.73800 32.33
23 -52.8529 0.955
24 113.2572 5.800 1.59349 66.99
25 -32.1120 D25 (Variable)
26 -120.6162 3.500 1.74389 49.53
27* -50.8923 D27 (variable)
28 -61.4253 3.215 1.94595 17.98
29 -34.3446 0.200
30* -69.3409 1.500 1.85108 40.12
31 72.0715 6.683
32 -23.1150 1.400 1.69680 55.52
33 -36.7553 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4=4.34838E-06, A6=-2.30274E-09
A8=1.34342E-12, A10=2.08876E-15, A12=0.00000E+00
15th surface κ=1.0000, A4=-4.08736E-06, A6=2.82731E-09
A8=-1.71368E-11, A10=2.81580E-14, A12=0.00000E+00
27th surface κ=1.0000, A4=9.77330E-06, A6=-1.31611E-08
A8=7.02329E-11, A10=-1.28887E-13, A12=0.00000E+00
30th surface κ=1.0000, A4=-3.68898E-06, A6=-1.92901E-08
A8=3.36794E-11, A10=-8.19805E-14, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 133.226
G2 6 -23.579
G3 14 40.561
G4 19 115.254
G5 22 113.536
G6 26 115.868
G7 28 -42.726
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 2.000 18.194 30.046 2.000 18.194 30.046
D13 21.479 6.645 2.000 21.479 6.645 2.000
D18 9.801 4.462 1.500 9.801 4.462 1.500
D21 5.195 13.414 18.760 4.220 12.328 17.590
D25 2.295 3.824 2.737 2.742 4.222 2.950
D27 5.890 2.000 2.087 6.417 2.689 3.043
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=0.352
Conditional expression (2) dP1/f1=0.061
Conditional expression (3) |fF|/ft=1.706
Conditional expression (4) nN/nP = 1.160
Conditional expression (5) νN/νP = 0.392
Conditional expression (6) f1/|fRw|=0.384
Conditional expression (7) 2ωw=85.08
Conditional expression (8) BFw/fw=0.475
Conditional expression (9) (rR2+rR1)/(rR2-rR1)=4.389

5(A), 5(B), and 5(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the second embodiment, respectively, when focusing on infinity. is a diagram of various aberrations. 6(A), 6(B), and 6(C) respectively show the zooming optical system according to the second embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations. From the various aberration diagrams, it can be seen that the variable magnification optical system of Example 2 has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 7 to 9 and Table 3. FIG. FIG. 7 is a diagram showing the lens configuration of the variable magnification optical system according to the third embodiment. A variable magnification optical system ZL(3) according to the third embodiment includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a third lens group G5 having positive refractive power. It consists of 6 lens groups G6 and a 7th lens group G7 having negative refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the subsequent lens group GR, and has negative refractive power as a whole.

The first lens group G1 includes a positive lens cemented with a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12 arranged in order from the object side, and a positive meniscus lens having a convex surface facing the object side. L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a concave surface on the object side. and a negative meniscus lens L24. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive meniscus lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 is composed of a cemented positive lens constructed by cementing a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42.

The fifth lens group G5 is composed of, in order from the object side, a negative meniscus lens L51 having a concave surface facing the object side and a biconvex positive lens L52.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side. The positive meniscus lens L61 has an aspheric lens surface on the image side.

The seventh lens group G7 includes, in order from the object side, a negative meniscus lens L71 with a convex surface facing the object side, a positive meniscus lens L72 with a concave surface facing the object side, and a negative meniscus lens with a concave surface facing the object side. L73. The negative meniscus lens L73 has an aspheric lens surface on the object side. An image plane I is arranged on the image side of the seventh lens group G7.

In this embodiment, by independently moving the fifth lens group G5 and the sixth lens group G6 toward the object side, focusing from a long distance object to a short distance object (from an infinite distance object to a finite distance object) can be performed. done. That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

Table 3 below lists the values of the specifications of the variable power optical system according to the third example.

(Table 3)
[Overall specifications]
Zoom ratio 3.33
fRw = -219.096
WMT
f 24.8 50.0 82.5
FNO 2.92 2.92 2.92
2ω 85.12 45.44 28.34
Ymax 21.60 21.60 21.60
TL 150.97 164.85 185.45
BF 11.75 21.93 30.78
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 454.1335 2.500 1.94594 17.98
2 158.8346 5.629 1.81600 46.59
3-1850.8518 0.200
4 62.5732 5.149 1.81600 46.59
5 111.4228 D5 (variable)
6* 143.7538 2.000 1.81600 46.59
7 20.1321 9.695
8 -48.3009 2.346 1.88300 40.66
9 156.4679 0.200
10 65.6396 6.565 1.80518 25.45
11 -42.2522 2.354
12 -26.3896 1.200 1.69680 55.52
13 -61.8795 D13 (Variable)
14 ∞ 1.500 (Aperture S)
15* 46.9137 2.985 1.81600 46.59
16 79.9069 0.200
17 56.4482 6.543 1.49782 82.57
18 -69.0474 D18 (Variable)
19 78.4165 1.300 1.90366 31.27
20 26.6178 9.263 1.59319 67.90
21 -58.5857 D21 (Variable)
22 -29.0948 1.200 1.80100 34.92
23 -53.3089 2.957
24 64.8393 6.500 1.48749 70.32
25 -36.2810 D25 (Variable)
26 -486.6338 2.667 1.58887 61.13
27* -77.9833 D27 (Variable)
28 208.9420 1.200 1.90366 31.27
29 40.1016 3.903
30 -103.6980 6.199 1.84666 23.80
31 -35.7067 3.104
32* -19.6292 1.500 1.81600 46.59
33 -40.5502 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4=4.25283E-06, A6=-2.28156E-09
A8=-7.12258E-14, A10=7.16065E-15, A12=0.00000E+00
15th surface κ=1.0000, A4=-3.75837E-06, A6=9.56813E-10
A8=-1.31531E-12, A10=1.97978E-16, A12=0.00000E+00
27th surface κ=1.0000, A4=1.09037E-05, A6=-5.09501E-11
A8=-1.76649E-12, A10=1.58609E-14, A12=0.00000E+00
32nd surface κ=1.0000, A4=1.01091E-05, A6=1.61408E-08
A8=3.76726E-12, A10=1.25182E-13, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 130.092
G2 6 -23.049
G3 14 44.414
G4 19 100.000
G5 22 98.812
G6 26 157.320
G7 28-42.703
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 2.000 21.323 36.906 2.000 21.323 36.906
D13 25.662 7.746 2.000 25.662 7.746 2.000
D18 9.597 5.312 1.500 9.597 5.312 1.500
D21 6.192 11.864 21.415 5.303 10.833 20.070
D25 2.000 3.105 2.000 2.411 3.415 2.346
D27 4.901 4.716 2.000 5.379 5.438 2.999
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=0.444
Conditional expression (2) dP1/f1=0.062
Conditional expression (3) |fF|/ft=1.907
Conditional expression (4) nN/nP = 1.195
Conditional expression (5) νN/νP = 0.461
Conditional expression (6) f1/|fRw|=0.594
Conditional expression (7) 2ωw=85.12
Conditional expression (8) BFw/fw=0.475
Conditional expression (9) (rR2+rR1)/(rR2-rR1)=2.877

8(A), 8(A), and 8(C) show the zoom lens system according to the third embodiment when focusing on infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 9(A), 9(B), and 9(C) show the close-distance focusing in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the third embodiment, respectively. is a diagram of various aberrations. From the various aberration diagrams, it can be seen that the variable magnification optical system of Example 3 has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 10 to 12 and Table 4. FIG. FIG. 10 is a diagram showing the lens configuration of the variable power optical system according to the fourth example. A variable magnification optical system ZL(4) according to the fourth embodiment includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a third lens group G5 having negative refractive power. It is composed of six lens groups G6. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to sixth lens groups G1 to G6 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5 and the sixth lens group G6 corresponds to the subsequent lens group GR and has negative refractive power as a whole.

The first lens group G1 includes a positive lens cemented with a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side, and a positive lens having a convex surface facing the object side. and a positive meniscus lens L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive meniscus lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a concave surface on the object side. and a negative meniscus lens L24. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive meniscus lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 is composed of a cemented positive lens constructed by cementing a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42.

The fifth lens group G5 is composed of, in order from the object side, a negative meniscus lens L51 with a concave surface facing the object side, a biconvex positive lens L52, and a positive meniscus lens L53 with a concave surface facing the object side. be done. The positive meniscus lens L53 has an aspheric lens surface on the image side.

The sixth lens group G6 is composed of, in order from the object side, a positive meniscus lens L61 with a concave surface facing the object side, a biconcave negative lens L62, and a negative meniscus lens L63 with a concave surface facing the object side. be done. The negative lens L62 has an aspheric lens surface on the object side. An image plane I is arranged on the image side of the sixth lens group G6.

In this embodiment, by moving the fifth lens group G5 toward the object side, focusing from a long distance object to a short distance object (from an infinite distance object to a finite distance object) is performed. That is, the fifth lens group G5 corresponds to a focusing lens group.

Table 4 below lists values of specifications of the variable-magnification optical system according to the fourth example.

(Table 4)
[Overall specifications]
Zoom ratio 2.75
fRw = -356.649
WMT
f 24.7 50.0 67.9
FNO 2.92 2.92 2.92
2ω 85.08 45.26 33.84
Ymax 21.60 21.60 21.60
TL 139.95 154.92 168.36
BF 11.75 26.42 30.21
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 500.0000 2.500 1.84666 23.80
2 128.5654 5.629 1.77250 49.62
3 1528.3565 0.200
4 51.0685 4.893 1.81600 46.59
5 84.5957 D5 (variable)
6* 150.2756 2.000 1.74389 49.53
7 19.5218 9.332
8 -70.5990 1.300 1.83481 42.73
9 68.8663 0.377
10 44.7171 5.665 1.78472 25.64
11 -66.3119 4.463
12 -25.4625 1.300 1.60300 65.44
13 -54.4747 D13 (Variable)
14 ∞ 1.500 (Aperture S)
15* 93.5557 2.758 1.58913 61.15
16 731.3943 0.200
17 45.8800 5.212 1.59319 67.90
18 -126.9127 D18 (Variable)
19 57.2400 1.300 1.73800 32.33
20 21.3782 8.742 1.49782 82.57
21 -52.7685 D21 (Variable)
22 -23.6692 1.200 1.73800 32.33
23 -59.4644 0.200
24 110.3346 5.800 1.59349 67.00
25 -32.1046 4.444
26 -114.5585 3.326 1.74389 49.53
27* -41.8456 D27 (variable)
28 -51.0521 2.929 1.94594 17.98
29 -33.3238 0.200
30* -98.8101 1.500 1.85108 40.12
31 58.4711 6.329
32 -25.4692 1.400 1.69680 55.52
33 -42.7921 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4=4.65692E-06, A6=-1.64542E-09
A8=3.72186E-13, A10=4.82369E-15, A12=0.00000E+00
15th surface κ=1.0000, A4=-3.70657E-06, A6=3.18672E-09
A8=-1.82835E-11, A10=3.59863E-14, A12=0.00000E+00
27th surface κ=1.0000, A4=1.13375E-05, A6=-1.49475E-08
A8=6.38011E-11, A10=-1.10074E-13, A12=0.00000E+00
30th surface κ=1.0000, A4=-5.84233E-06, A6=-2.49185E-08
A8=2.26680E-11, A10=-7.54165E-14, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 136.259
G2 6 -23.493
G3 14 44.223
G4 19 90.807
G5 22 53.777
G6 28-40.364
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 2.000 16.966 30.403 2.000 16.966 30.403
D13 20.342 6.266 2.000 20.342 6.266 2.000
D18 10.475 3.778 2.048 10.475 3.778 2.048
D21 4.711 14.758 17.000 4.046 13.957 16.055
D27 5.973 2.030 2.000 6.639 2.831 2.945
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=0.487
Conditional expression (2) dP1/f1=0.060
Conditional expression (3) |fF|/ft=0.792
Conditional expression (4) nN/nP = 1.160
Conditional expression (5) νN/νP = 0.392
Conditional expression (6) f1/|fRw|=0.382
Conditional expression (7) 2ωw=85.08
Conditional expression (8) BFw/fw=0.475
Conditional expression (9) (rR2+rR1)/(rR2-rR1)=3.941

11(A), 11(B), and 11(C) show the zoom lens system according to the fourth embodiment when focusing on infinity in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. is a diagram of various aberrations. 12(A), 12(B), and 12(C) respectively show the zooming optical system according to the fourth embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations. From the various aberration diagrams, it can be seen that the variable magnification optical system according to the fourth embodiment has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

(Fifth embodiment)
A fifth embodiment will be described with reference to FIGS. 13 to 15 and Table 5. FIG. FIG. 13 is a diagram showing the lens configuration of the variable magnification optical system according to the fifth embodiment. A variable magnification optical system ZL(5) according to the fifth embodiment includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a third lens group G5 having positive refractive power. It is composed of six lens groups G6. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to sixth lens groups G1 to G6 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5 and the sixth lens group G6 corresponds to the subsequent lens group GR and has negative refractive power as a whole.

The first lens group G1 includes a cemented negative lens composed of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12 arranged in order from the object side, and a positive meniscus lens having a convex surface facing the object side. L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a positive meniscus lens L23 with a convex surface facing the object side, and an object lens. and a negative meniscus lens L24 with a concave surface on the side. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive meniscus lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 includes a biconvex positive lens L41, a cemented negative lens composed of a biconvex negative lens L42 cemented with a biconvex positive lens L43, and a biconvex positive lens L43, arranged in order from the object side. and a lens L44. The positive lens L41 has an aspheric lens surface on the object side. The positive lens L44 has an aspheric lens surface on the image side.

The fifth lens group G5 is composed of, in order from the object side, a positive meniscus lens L51 having a concave surface facing the object side, a biconcave negative lens L52, and a biconcave negative lens L53. The negative lens L53 has an aspheric lens surface on the object side.

The sixth lens group G6 is composed of a biconvex positive lens L61. An image plane I is arranged on the image side of the sixth lens group G6.

In this embodiment, by moving the fifth lens group G5 toward the image plane I, focusing from a long-distance object to a short-distance object (from an infinite-distance object to a finite-distance object) is performed. That is, the fifth lens group G5 corresponds to a focusing lens group.

Table 5 below lists the values of the specifications of the variable power optical system according to the fifth example.

(Table 5)
[Overall specifications]
Zoom ratio 2.75
fRw = -45.339
WMT
f 24.7 50.0 67.9
FNO 2.92 2.92 2.92
2ω 85.16 45.24 34.12
Ymax 21.60 21.60 21.60
TL 134.73 154.61 169.45
BF 13.56 26.94 34.84
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 10957.4900 2.500 1.84666 23.80
2 273.2507 3.923 1.59319 67.90
3-4164.8091 0.200
4 97.8909 5.850 1.81600 46.59
5 1686.5488 D5 (variable)
6* 500.0000 2.000 1.67798 54.89
7 19.6217 7.571
8 -119.4257 1.200 1.59319 67.90
9 74.2767 0.211
10 36.8572 5.028 1.85000 27.03
11 146.1931 4.217
12 -25.9063 1.200 1.60300 65.44
13 -48.3220 D13 (Variable)
14 ∞ 1.500 (Aperture S)
15* 31.8609 3.346 1.79504 28.69
16 60.3817 1.288
17 65.3208 3.503 1.49782 82.57
18 -22831.8850 D18 (variable)
19* 52.1943 4.361 1.82098 42.50
20 -99.8775 0.663
21 -484.1811 1.200 1.85478 24.80
22 19.0497 8.079 1.49782 82.57
23 -86.9834 3.675
24 61.0249 5.155 1.80604 40.74
25* -60.8291 D25 (variable)
26 -310.5249 2.912 1.94594 17.98
27 -59.5174 0.200
28 -155.6589 1.200 1.77250 49.62
29 30.4299 6.880
30* -54.7368 1.300 1.95150 29.83
31 317.1233 D31 (variable)
32 72.1520 4.819 1.83481 42.73
33-315.4491 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4= 5.57412E-06, A6=-5.71627E-09
A8=9.08385E-12, A10=-4.74214E-15, A12=0.00000E+00
15th surface κ=1.0000, A4=-5.90450E-06, A6=3.98445E-09
A8=-4.29920E-11, A10=9.10161E-14, A12=0.00000E+00
19th surface κ=1.0000, A4=-5.71112E-06, A6=-6.16170E-10
A8=2.42198E-11, A10=-5.71940E-14, A12=0.00000E+00
25th surface κ=1.0000, A4=2.37352E-06, A6=-6.63258E-09
A8=-2.39696E-11, A10=1.99908E-14, A12=0.00000E+00
30th surface κ=1.0000, A4=-6.17314E-06, A6=-3.26346E-08
A8=1.32620E-10, A10=-6.33629E-13, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 139.410
G2 6 -23.353
G3 14 51.116
G4 19 31.271
G5 26 -24.892
G6 32 70.741
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 2.000 21.443 31.758 2.000 21.443 31.758
D13 19.908 6.376 2.000 19.908 6.376 2.000
D18 9.100 3.184 2.000 9.100 3.184 2.000
D25 3.162 2.189 2.000 3.569 2.602 2.454
D31 3.023 10.499 12.881 2.616 10.087 12.426
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=1.635
Conditional expression (2) dP1/f1=0.046
Conditional expression (3) |fF|/ft=0.367
Conditional expression (4) nN/nP = 1.238
Conditional expression (5) νN/νP = 0.300
Conditional expression (6) f1/|fRw|=3.075
Conditional expression (7) 2ωw=85.16
Conditional expression (8) BFw/fw=0.548
Conditional expression (10) (rR2+rR1)/(rR2-rR1)=0.628

14(A), 14(B), and 14(C) are the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the fifth embodiment, respectively, when focusing at infinity. is a diagram of various aberrations. 15(A), 15(B), and 15(C) show the zoom optical system according to the fifth embodiment when focusing at a short distance in the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively. is a diagram of various aberrations. From the various aberration diagrams, it can be seen that the variable power optical system according to the fifth embodiment has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

(Sixth embodiment)
A sixth embodiment will be described with reference to FIGS. 16 to 18 and Table 6. FIG. FIG. 16 is a diagram showing the lens configuration of the variable power optical system according to the sixth example. A variable magnification optical system ZL(6) according to the sixth embodiment includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having negative refractive power, and a third lens group G5 having positive refractive power. It consists of 6 lens groups G6 and a 7th lens group G7 having a positive refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the subsequent lens group GR, and has negative refractive power as a whole.

The first lens group G1 includes a cemented negative lens composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side, and a negative lens cemented with a convex surface facing the object side. and a positive meniscus lens L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive meniscus lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a positive meniscus lens L23 with a convex surface facing the object side, and an object lens. and a negative meniscus lens L24 with a concave surface on the side. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive meniscus lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 includes a biconvex positive lens L41, a cemented negative lens composed of a biconvex negative lens L42 cemented with a biconvex positive lens L43, and a biconvex positive lens L43, arranged in order from the object side. and a lens L44. The positive lens L41 has an aspheric lens surface on the object side. The positive lens L44 has an aspheric lens surface on the image side.

The fifth lens group G5 is composed of, in order from the object side, a positive meniscus lens L51 having a concave surface facing the object side, a biconcave negative lens L52, and a biconcave negative lens L53. The negative lens L53 has an aspheric lens surface on the object side.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a convex surface facing the object side.

The seventh lens group G7 is composed of a biconvex positive lens L71. An image plane I is arranged on the image side of the seventh lens group G7.

In this embodiment, by moving the fifth lens group G5 toward the image plane I, focusing from a long-distance object to a short-distance object (from an infinite-distance object to a finite-distance object) is performed. That is, the fifth lens group G5 corresponds to a focusing lens group.

Table 6 below lists values of specifications of the variable-magnification optical system according to the sixth example.

(Table 6)
[Overall specifications]
Zoom ratio 2.74
fRw = -40.687
WMT
f 24.8 50.0 67.9
FNO 2.96 2.98 2.99
2ω 85.16 45.20 34.12
Ymax 21.60 21.60 21.60
TL 138.57 158.72 174.45
BF 13.13 25.93 34.76
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 800.0000 2.500 1.84666 23.80
2 214.4014 3.846 1.59319 67.90
3 1317.1215 0.200
4 112.4262 5.452 1.81600 46.59
5 6769.9563 D5 (variable)
6* 500.0000 2.000 1.67798 54.89
7 20.1483 7.488
8 -122.7141 1.200 1.59319 67.90
9 65.7886 0.272
10 36.9186 6.199 1.85000 27.03
11 167.8314 4.151
12 -26.0907 1.200 1.60300 65.44
13 -47.5468 D13 (Variable)
14 ∞ 1.500 (Aperture S)
15* 34.4078 3.172 1.79504 28.69
16 61.0992 1.040
17 57.2334 3.808 1.49782 82.57
18 -5887.8063 D18 (variable)
19* 56.4489 4.200 1.82098 42.50
20 -110.1792 0.505
21 -291.5983 1.200 1.85478 24.80
22 21.3003 9.632 1.49782 82.57
23 -65.8810 3.027
24 55.5374 5.156 1.80604 40.74
25* -64.8934 D25 (variable)
26 -368.5041 2.887 1.94594 17.98
27 -62.4504 0.200
28 -158.4306 1.200 1.77250 49.62
29 31.1763 6.060
30* -91.4544 1.300 1.95150 29.83
31 81.4249 D31 (variable)
32 57.0897 2.149 1.80518 25.45
33 69.0085 D33 (variable)
34 73.7084 4.702 1.64000 60.19
35-314.5384 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4=4.89442E-06, A6=-5.03173E-09
A8=9.04508E-12, A10=-5.83062E-15, A12=0.00000E+00
15th surface κ=1.0000, A4=-5.12384E-06, A6=3.61548E-09
A8=-3.66003E-11, A10=7.76731E-14, A12=0.00000E+00
19th surface κ=1.0000, A4=-5.21485E-06, A6=-8.93869E-10
A8=2.28848E-11, A10=-5.34780E-14, A12=0.00000E+00
25th surface κ=1.0000, A4=3.45860E-06, A6=-6.25344E-09
A8=-1.37950E-11, A10=2.51017E-14, A12=0.00000E+00
30th surface κ=1.0000, A4=-6.74203E-06, A6=-2.42770E-08
A8=5.92492E-11, A10=-3.49332E-13, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 152.425
G2 6 -24.007
G3 14 52.775
G4 19 30.001
G5 26 -24.147
G6 32 379.967
G7 34 93.748
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 2.000 22.083 33.118 2.000 22.083 33.118
D13 20.464 6.484 2.000 20.464 6.484 2.000
D18 9.842 3.320 2.000 9.842 3.320 2.000
D25 2.978 2.225 2.053 3.339 2.586 2.447
D31 2.915 10.198 13.200 2.555 9.837 12.806
D33 1.000 2.234 1.084 1.000 2.234 1.084
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=1.759
Conditional expression (2) dP1/f1=0.042
Conditional expression (3) |fF|/ft=0.356
Conditional expression (4) nN/nP = 1.238
Conditional expression (5) νN/νP = 0.300
Conditional expression (6) f1/|fRw|=3.746
Conditional expression (7) 2ωw=85.16
Conditional expression (8) BFw/fw=0.530
Conditional expression (10) (rR2+rR1)/(rR2-rR1)=0.620

17(A), 17(B), and 17(C) show the zoom optical system according to the sixth embodiment when focusing at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 18(A), 18(B), and 18(C) show the zoom optical system according to the sixth embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state, respectively, when focusing at a short distance. is a diagram of various aberrations. From the various aberration diagrams, it can be seen that the variable magnification optical system according to the sixth embodiment has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

(Seventh embodiment)
A seventh embodiment will be described with reference to FIGS. 19 to 21 and Table 7. FIG. FIG. 19 is a diagram showing the lens configuration of the variable magnification optical system according to the seventh embodiment. A variable magnification optical system ZL(7) according to the seventh embodiment includes a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, and an aperture, arranged in order from the object side. A diaphragm S, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, a fifth lens group G5 having positive refractive power, and a third lens group G5 having positive refractive power. It consists of 6 lens groups G6 and a 7th lens group G7 having negative refractive power. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first to seventh lens groups G1 to G7 move in the directions indicated by the arrows in FIG. Change. A lens group consisting of the fifth lens group G5, the sixth lens group G6, and the seventh lens group G7 corresponds to the subsequent lens group GR, and has positive refractive power as a whole.

The first lens group G1 includes a positive lens cemented with a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side, arranged in order from the object side, and a positive lens having a convex surface facing the object side. and a positive meniscus lens L13. The negative meniscus lens L11 corresponds to the eleventh lens. The positive meniscus lens L12 corresponds to the 12th lens.

The second lens group G2 includes, in order from the object side, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, a biconvex positive lens L23, and a concave surface on the object side. and a negative meniscus lens L24. The negative meniscus lens L21 has an aspheric lens surface on the object side.

The third lens group G3 is composed of, in order from the object side, a positive meniscus lens L31 having a convex surface facing the object side and a biconvex positive lens L32. An aperture stop S is provided near the object side of the third lens group G3, and moves together with the third lens group G3 during zooming. The positive meniscus lens L31 corresponds to the 31st lens and has an aspheric lens surface on the object side. The positive lens L32 corresponds to the 32nd lens.

The fourth lens group G4 is composed of a cemented positive lens constructed by cementing a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42.

The fifth lens group G5 is composed of, in order from the object side, a negative meniscus lens L51 having a concave surface facing the object side and a biconvex positive lens L52.

The sixth lens group G6 is composed of a positive meniscus lens L61 having a concave surface facing the object side. The positive meniscus lens L61 has an aspheric lens surface on the image side.

The seventh lens group G7 is composed of, in order from the object side, a positive meniscus lens L71 with a concave surface facing the object side, a biconcave negative lens L72, and a negative meniscus lens L73 with a concave surface facing the object side. be. An image plane I is arranged on the image side of the seventh lens group G7. The negative lens L72 has an aspheric lens surface on the object side.

In this embodiment, by independently moving the fifth lens group G5 and the sixth lens group G6 toward the object side, focusing from a long distance object to a short distance object (from an infinite distance object to a finite distance object) can be performed. done. That is, the fifth lens group G5 corresponds to the first focusing lens group, and the sixth lens group G6 corresponds to the second focusing lens group.

Table 7 below lists the values of the specifications of the variable-magnification optical system according to the seventh example.

(Table 7)
[Overall specifications]
Zoom ratio 2.74
fRw = 4055.914
WMT
f 24.8 50.0 67.9
FNO 2.92 2.92 2.92
2ω 85.10 45.24 33.84
Ymax 21.60 21.60 21.60
TL 139.31 158.27 168.76
BF 11.75 23.48 28.76
[Lens specifications]
Surface number R D nd νd
Object plane ∞
1 189.0188 2.500 1.84666 23.80
2 98.2637 5.200 1.75500 52.33
3 281.1360 0.200
4 58.7593 5.700 1.77250 49.62
5 135.0000 D5 (variable)
6* 221.1138 2.000 1.74389 49.53
7 18.6091 9.662
8 -58.7660 1.300 1.77250 49.62
9 58.7660 0.506
10 39.8268 6.400 1.72825 28.38
11 -48.5880 1.773
12 -26.6513 1.300 1.61800 63.34
13 -70.7180 D13 (Variable)
14 ∞ 1.702 (Aperture S)
15* 71.3000 2.500 1.69370 53.32
16 121.5261 0.202
17 38.6117 5.900 1.59319 67.90
18 -111.3842 D18 (Variable)
19 66.4297 1.300 1.73800 32.33
20 19.7070 9.700 1.49782 82.57
21 -49.1811 D21 (Variable)
22 -23.7160 1.200 1.72047 34.71
23 -55.5303 0.200
24 103.5406 5.980 1.59349 67.00
25 -32.7186 D25 (Variable)
26 -75.1626 3.736 1.79189 45.04
27* -39.1303 D27 (variable)
28 -44.6016 3.000 1.94594 17.98
29 -32.9994 0.201
30* -101.4301 1.500 1.85207 40.15
31 85.4850 7.927
32 -25.8904 1.400 1.58913 61.22
33 -45.0397 BF
Image plane ∞
[Aspheric data]
6th surface κ=1.0000, A4=5.47971E-06, A6=-6.22095E-09
A8=1.44104E-11, A10=-2.08855E-14, A12=2.01910E-17
15th surface κ=1.0000, A4=-4.50985E-06, A6=2.81159E-10
A8=-2.63745E-12, A10=-4.80538E-15, A12=0.00000E+00
27th surface κ=1.0000, A4=1.09182E-05, A6=-2.25976E-08
A8=1.43325E-10, A10=-4.96895E-13, A12=6.77820E-16
30th surface κ=1.0000, A4=-2.19229E-06, A6=-2.44256E-08
A8=6.38954E-11, A10=-1.65927E-13, A12=0.00000E+00
[Lens group data]
Group Starting surface Focal length
G1 1 118.121
G2 6 -21.898
G3 14 41.497
G4 19 109.585
G5 22 123.527
G6 26 98.560
G7 28 -47.807
[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D5 1.800 21.061 29.930 1.800 21.061 29.930
D13 19.119 6.127 2.000 19.119 6.127 2.000
D18 9.354 3.967 1.500 9.354 3.967 1.500
D21 5.286 14.229 18.845 4.337 12.953 17.517
D25 2.861 3.580 2.713 3.291 4.145 3.115
D27 6.143 2.841 2.028 6.662 3.552 2.955
[Value corresponding to conditional expression]
Conditional expression (1) f3/f4=0.379
Conditional expression (2) dP1/f1=0.065
Conditional expression (3) |fF|/ft=1.819
Conditional expression (4) nN/nP = 1.160
Conditional expression (5) νN/νP = 0.392
Conditional expression (6) f1/|fRw|=0.029
Conditional expression (7) 2ωw=85.10
Conditional expression (8) BFw/fw=0.475
Conditional expression (9) (rR2+rR1)/(rR2-rR1)=3.704

20(A), 20(B), and 20(C) show the zoom optical system according to the seventh embodiment when focusing on infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively. is a diagram of various aberrations. 21(A), 21(C), and 21(C) respectively show the zooming optical system according to the seventh embodiment at the wide-angle end state, the intermediate focal length state, and the telephoto end state during close-distance focusing. is a diagram of various aberrations. From the various aberration diagrams, it can be seen that the variable power optical system of Example 7 has excellent imaging performance with good correction of various aberrations from the wide-angle end state to the telephoto end state. It can be seen that both have excellent imaging performance.

According to each embodiment, it is possible to achieve high-speed and quiet autofocus without increasing the size of the lens barrel. It is possible to realize a variable-magnification optical system that suppresses fluctuations in aberration when focusing from an object to a short-distance object.

Here, the above-described first to seventh examples show specific examples of the present embodiment, and the present embodiment is not limited to these.

It should be noted that the following content can be appropriately adopted within a range that does not impair the optical performance of the variable-magnification optical system according to this embodiment.

Numerical examples of the variable power optical system are those with a 6-group configuration and a 7-group configuration, but the present application is not limited to this, and a variable power optical system with other group configurations (e.g., 8 groups, etc.) can be configured. You can also Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image plane side of the variable power optical system may be used. Note that the lens group refers to a portion having at least one lens separated by an air gap that changes during zooming.

The lens surface may be spherical, planar, or aspherical. A spherical or flat lens surface is preferable because it facilitates lens processing and assembly adjustment and prevents degradation of optical performance due to errors in processing and assembly adjustment. Also, even if the image plane is deviated, there is little deterioration in rendering performance, which is preferable.

If the lens surface is aspherical, the aspherical surface can be ground aspherical, glass-molded aspherical, which is formed into an aspherical shape from glass, or composite aspherical, which is formed into an aspherical shape from resin on the surface of glass. It doesn't matter which one. Further, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

The aperture stop is preferably arranged between the second lens group and the third lens group, but the role of the aperture stop may be substituted by a lens frame without providing a member as the aperture stop.

Each lens surface may be provided with an anti-reflection film having high transmittance over a wide wavelength range in order to reduce flare and ghost and achieve high-contrast optical performance. As a result, flare and ghost can be reduced, and high contrast and high optical performance can be achieved.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group I Image plane S Aperture diaphragm

Claims (16)

A first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a third lens group having positive refractive power, arranged in order from the object side. 4 lens groups and a subsequent lens group,
The subsequent lens group has a fifth lens group and a sixth lens group arranged in order from the object side,
When zooming, the distance between adjacent lens groups changes,
the trailing lens group has a focusing lens group that moves during focusing;
The focusing lens group is arranged on the image side of the aperture stop,
The first lens group comprises a first lens having negative refractive power, a second lens having positive refractive power, and a third lens having positive refractive power, arranged in order from the object side. become,
The third lens group comprises one or more lenses having positive refractive power, including a single lens having positive refractive power disposed closest to the object side of the third lens group,
A variable magnification optical system that satisfies the following conditional expressions.
0.20<f3/f4<2.50
where f3: focal length of the third lens group f4: focal length of the fourth lens group 2. A variable magnification optical system according to claim 1, wherein said third lens group comprises two single lenses having positive refractive power. 3. A variable-magnification optical system according to claim 1, which satisfies the following conditional expression.
0.010<dP1/f1<0.075
where dP1: the sum of the center thickness of the first lens and the center thickness of the second lens f1: the focal length of the first lens group 4. The variable power optical system according to any one of claims 1 to 3, wherein the focusing lens group comprises three or less single lenses. 5. The variable power optical system according to claim 1, wherein at least one of said focusing lens groups has a single lens with negative refractive power. 6. The variable magnification optical system according to any one of claims 1 to 5, wherein at least four lens groups are arranged on the image side of the aperture stop. 7. The variable power optical system according to claim 1, which satisfies the following conditional expressions.
0.20<|fF|/ft<4.00
However, fF: the focal length of the focusing lens group having the strongest refractive power among the focusing lens groups, ft: the focal length of the variable magnification optical system in the telephoto end state. The variable power optical system according to any one of claims 1 to 7, wherein the fourth lens group has a cemented lens composed of a negative lens and a positive lens. The fourth lens group has a cemented lens of a negative lens and a positive lens,
9. A variable-magnification optical system according to claim 1, which satisfies the following conditional expressions.
1.00<nN/nP<1.35
where nN: refractive index of the negative lens in the cemented lens nP: refractive index of the positive lens in the cemented lens The fourth lens group has a cemented lens of a negative lens and a positive lens,
A variable power optical system according to any one of claims 1 to 9, which satisfies the following conditional expressions.
0.20<νN/νP<0.85
where νN: Abbe number of the negative lens in the cemented lens νP: Abbe number of the positive lens in the cemented lens A variable power optical system according to any one of claims 1 to 10, which satisfies the following conditional expressions.
f1/|fRw|<5.00
where f1: focal length of the first lens group fRw: focal length of the subsequent lens group in the wide-angle end state 12. The variable magnification optical system according to claim 1, which satisfies the following conditional expressions.
2ωw>75°
where ωw is the half angle of view of the variable magnification optical system in the wide-angle end state 13. The variable magnification optical system according to claim 1, which satisfies the following conditional expressions.
0.10<BFw/fw<1.00
where BFw: back focus of the variable power optical system in the wide-angle end state fw: focal length of the variable power optical system in the wide-angle end state 14. The variable magnification optical system according to any one of claims 1 to 13, wherein the following conditional expression is satisfied when the focusing lens group has positive refractive power.
0.00<(rR2+rR1)/(rR2-rR1)<8.00
where rR1 is the radius of curvature of the object-side lens surface of the lens closest to the image side in the variable power optical system, rR2 is the radius of curvature of the image-side lens surface of the lens closest to the image side of the variable power optical system curvature radius 14. The variable power optical system according to any one of claims 1 to 13, wherein the following conditional expression is satisfied when the focusing lens group has negative refractive power.
-4.00<(rR2+rR1)/(rR2-rR1)<4.00
where rR1 is the radius of curvature of the object-side lens surface of the lens closest to the image side in the variable power optical system, rR2 is the radius of curvature of the image-side lens surface of the lens closest to the image side of the variable power optical system curvature radius An optical apparatus equipped with the variable magnification optical system according to any one of claims 1 to 15.

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