JP2023065557A - Variable power optical system, optical device, and method for manufacturing variable power optical system - Google Patents

Abstract

SOLUTION: The present invention comprises, in an order from an object side, 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 subsequent lens group having negative refractive power. At zooming from a wide-angle end state to a telephone end state, an interval between the first and second lens groups changes, an interval between the second and third lens groups changes, and an interval between the third and subsequent lens groups changes. The third or the substrate lens group includes a focusing lens group that moves when being focused from an infinite distance object to a short distance object, making it possible to satisfy a prescribed conditional expression so as to suitably correct various aberrations.

EFFECT: According to a method for manufacturing a variable power optical system in the present embodiment, it is possible to realize a variable power optical system having a high optical performance, which is compact yet can respond to a large-sized imaging element and suitably correct various aberrations from a wide-angle end state up to a telephoto end state, and which further exhibits a high image-forming performance when focusing to a near distance object.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a variable power optical system, an optical device, and a method of manufacturing a variable power optical system.

2. Description of the Related Art Conventionally, there has been proposed a variable power optical system that is small but compatible with a large image pickup device and capable of high-speed focusing suitable for moving image shooting. For example, see JP-A-2015-064492. However, conventional variable power optical systems do not sufficiently correct various aberrations.

JP 2015-064492 A

The present invention
In order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a subsequent lens group with negative refractive power. and
During zooming, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the subsequent lens group change. The interval between and changes,
the third lens group or the subsequent lens group has a focusing lens group that moves during focusing;
This is a variable magnification optical system that satisfies the following conditional expression.
2.00 < f1/fw < 8.000
0.400<BFw/fw<1.300
however,
f1: focal length of the first lens group fw: focal length of the variable power optical system in the wide-angle end state BFw: back focus (air conversion length) of the variable power optical system in the wide-angle end state
fw: focal length of the variable magnification optical system in the wide-angle end state

In addition, the present invention
In order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a subsequent lens group with negative refractive power. A method for manufacturing a variable magnification optical system comprising
During zooming, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the subsequent lens group change. Configured so that the interval between and
wherein the third lens group or the subsequent lens group has a focusing lens group that moves during focusing;
This is a method of manufacturing a variable magnification optical system that satisfies the following conditional expressions.
2.00 < f1/fw < 8.000
0.400<BFw/fw<1.300
however,
f1: focal length of the first lens group fw: focal length of the variable power optical system in the wide-angle end state BFw: back focus (air conversion length) of the variable power optical system in the wide-angle end state
fw: focal length of the variable magnification optical system in the wide-angle end state

1A, 1B, and 1C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable power optical system according to the first embodiment. 2A, 2B, and 2C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the first embodiment, respectively, when focusing on an object at infinity. 3A, 3B, and 3C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the first embodiment, respectively, when focusing on a short-distance object. 4A, 4B, and 4C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable power optical system according to the second embodiment. 5A, 5B, and 5C are diagrams of various aberrations when focusing on an object at infinity in 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. 6A, 6B, and 6C are diagrams of various aberrations in 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 a short-distance object. 7A, 7B, and 7C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable magnification optical system according to the third example. 8A, 8B, and 8C are diagrams of various aberrations 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, when focusing on an object at infinity. 9A, 9B, and 9C are diagrams of various aberrations 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, when focusing on a short-distance object. 10A, 10B, and 10C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable power optical system according to the fourth example. FIGS. 11A, 11B, and 11C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the fourth example when focusing on an object at infinity. FIGS. 12A, 12B, and 12C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the fourth embodiment, respectively, when focusing on a short-distance object. 13A, 13B, and 13C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable magnification optical system according to the fifth example. 14A, 14B, and 14C are diagrams of various aberrations in 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 on an object at infinity. 15A, 15B, and 15C are diagrams of various aberrations in 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 on a short-distance object. FIG. 16 is a diagram showing the configuration of a camera equipped with a variable magnification optical system. FIG. 17 is a flowchart showing an outline of a method for manufacturing a variable power optical system.

A variable power optical system, an optical device, and a method for manufacturing the variable power optical system according to the present embodiment will be described below. First, a variable magnification optical system according to this embodiment will be described.

The variable power optical system according to this embodiment includes, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. and a subsequent lens group having a negative refractive power, wherein when zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the second lens group changes. The distance between the second lens group and the third lens group changes, the distance between the third lens group and the succeeding lens group changes, and the third lens group or the succeeding lens group changes from an object at infinity. It has a focusing lens group that moves when focusing on a distant object, and is constructed so as to satisfy the following conditional expressions (1) and (2).
(1) 2.00 < f1/fw < 8.000
(2) 0.400<BFw/fw<1.300
however,
f1: focal length of the first lens group fw: focal length of the variable power optical system in the wide-angle end state BFw: back focus (air conversion length) of the variable power optical system in the wide-angle end state
fw: focal length of the variable magnification optical system in the wide-angle end state

The subsequent lens group of the variable magnification optical system of this embodiment has at least one lens group. Note that the lens group in this embodiment means a portion having at least one lens separated by an air gap. Further, in this embodiment, the lens component refers to a single lens or a cemented lens formed by cementing two or more lenses.
The variable power optical system of this embodiment can achieve good aberration correction during zooming by changing the distance between the lens groups during zooming from the wide-angle end state to the telephoto end state. By arranging the focusing lens group in the third lens group or the subsequent lens group, the size and weight of the focusing lens group can be reduced. It is possible to reduce the size of the cylinder.

Conditional expression (1) defines the ratio between the focal length of the first lens group and the focal length of the variable power optical system in the wide-angle end state. By satisfying conditional expression (1), the variable power optical system of the present embodiment can satisfactorily correct various aberrations including coma in the wide-angle end state.

If the corresponding value of conditional expression (1) of the variable magnification optical system of this embodiment exceeds the upper limit, the refractive power of the first lens group becomes small, making it difficult to satisfactorily correct various aberrations in the wide-angle end state. Become. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (1) to 7.000. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (1) to 6.500, more preferably 6.300.

On the other hand, if the corresponding value of conditional expression (1) of the variable-magnification optical system of the present embodiment is below the lower limit, the refractive power of the first lens group increases, and various aberrations, especially coma, in the wide-angle end state are favorably reduced. It becomes difficult to correct. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (1) to 3.00. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (1) to 4.00, more preferably 4.50.

Conditional expression (2) defines the ratio between the back focus of the variable power optical system in the wide-angle end state and the focal length of the variable power optical system in the wide-angle end state. By satisfying conditional expression (2), the variable magnification optical system of the present embodiment can satisfactorily correct various aberrations including coma in the wide-angle end state. The back focus is the distance on the optical axis from the lens surface closest to the image side to the image plane.

When the corresponding value of conditional expression (2) of the variable-magnification optical system of the present embodiment exceeds the upper limit value, the back focus of the variable-magnification optical system in the wide-angle end state is becomes large, making it difficult to satisfactorily correct various aberrations in the wide-angle end state. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (2) to 1.000. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (2) to 0.950, more preferably 0.900.

On the other hand, if the corresponding value of conditional expression (2) of the variable-power optical system of the present embodiment is below the lower limit, the focal length of the variable-power optical system in the wide-angle end state is The back focus becomes small, and it becomes difficult to satisfactorily correct various aberrations, especially coma, in the wide-angle end state. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.500. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (2) to 0.600, more preferably 0.650.

In the conditional expression (2), "the back focus of the variable-magnification optical system in the wide-angle end state" indicated by BFw is assumed to be "the back focus of the variable-magnification optical system in the shortest state", and fw indicates the "wide-angle The focal length of the variable-magnification optical system in the extreme state may be replaced with the "focal length of the variable-magnification optical system in the shortest state." That is, conditional expression (2) may be expressed as follows.
(2) 0.400 < BFs/fs < 1.300
however,
BFs: back focus of the variable-magnification optical system with the shortest total length fs: focal length of the variable-magnification optical system with the shortest total length

With the above configuration, the variable power optical system of the present embodiment is compact, yet compatible with a large image pickup device, and is capable of satisfactorily correcting various aberrations during variable power and during focusing. system can be realized.

Moreover, it is desirable that the variable power optical system of this embodiment satisfy the following conditional expression (3).
(3) 0.500 < 1/βRw < 1.200
however,
βRw: Lateral magnification of the lens group closest to the image plane in the wide-angle end state

Conditional expression (3) defines the lateral magnification of the lens group closest to the image plane in the wide-angle end state. By satisfying the conditional expression (3), the variable power optical system of the present embodiment can satisfactorily correct various aberrations including astigmatism in the wide-angle end state.

When the corresponding value of conditional expression (3) of the variable-magnification optical system of the present embodiment exceeds the upper limit, the lateral magnification of the lens group arranged closest to the image plane in the wide-angle end state becomes small, causing various problems in the wide-angle end state. It becomes difficult to satisfactorily correct aberrations, especially astigmatism. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (3) to 1.100. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (3) to 1.000, more preferably 0.900.

On the other hand, when the corresponding value of conditional expression (3) of the variable-magnification optical system of the present embodiment falls below the lower limit, the lateral magnification of the lens group arranged closest to the image plane in the wide-angle end state increases, and the wide-angle end state increases. is likely to cause curvature of field, and it is difficult to satisfactorily correct various aberrations. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.550. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (3) to 0.580, more preferably 0.600.

Moreover, it is desirable that the variable power optical system of this embodiment satisfy the following conditional expression (4).
(4) 4.000 < f1/f1Rw < 9.000
however,
f1: focal length of the first lens group f1Rw: combined focal length in the wide-angle end state of the lens groups arranged closer to the image plane than the first lens group

Conditional expression (4) defines the ratio between the focal length of the first lens group and the combined focal length of the lens groups arranged closer to the image plane than the first lens group in the wide-angle end state. By satisfying conditional expression (4), the variable magnification optical system of the present embodiment can satisfactorily correct various aberrations including coma in the wide-angle end state. Further, by satisfying conditional expression (4), it is possible to suppress fluctuations in various aberrations including spherical aberration when zooming from the wide-angle end state to the telephoto end state.

When the corresponding value of conditional expression (4) of the variable-magnification optical system of this embodiment exceeds the upper limit, the refractive power of the lens group arranged closer to the image plane than the first lens group in the wide-angle end state becomes large. It becomes difficult to satisfactorily correct various aberrations, especially coma, in the end state. In addition, it becomes difficult to suppress variations in various aberrations including spherical aberration when zooming from the wide-angle end state to the telephoto end state. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (4) to 8.500. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (4) to 8.000, more preferably 7.000.

On the other hand, if the corresponding value of conditional expression (4) of the variable-magnification optical system of this embodiment falls below the lower limit, the refractive power of the first lens group increases, and various aberrations, especially coma, in the wide-angle end state are reduced. It becomes difficult to correct. In addition, it becomes difficult to suppress variations in various aberrations including spherical aberration when zooming from the wide-angle end state to the telephoto end state. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (4) to 5.000. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (4) to 5.100, more preferably 5.200.

Further, it is desirable that the variable magnification optical system of this embodiment satisfy the following conditional expression (5).
(5) nd3fp < 1.800
however,
nd3fp: refractive index of the lens with the highest refractive index in the third lens group

Conditional expression (5) defines the refractive index of the lens having the highest refractive power in the third lens group. The variable magnification optical system of this embodiment can satisfactorily correct longitudinal chromatic aberration and spherical aberration by using a glass material with high refractive power that satisfies conditional expression (5).

If the corresponding value of conditional expression (5) of the variable magnification optical system of this embodiment exceeds the upper limit, the refractive power of the third lens group increases, making it difficult to satisfactorily correct axial chromatic aberration and spherical aberration. Become. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.750. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (5) to 1.700, more preferably 1.650.

Moreover, it is desirable that the variable magnification optical system of this embodiment satisfy the following conditional expression (6).
(6) 50.000 < vd3p
however,
νd3p: Abbe number of the lens with the smallest Abbe number in the third lens group

Conditional expression (6) defines the Abbe number of the lens having the smallest Abbe number in the third lens group. In the variable magnification optical system of this embodiment, the third lens group can be made to have anomalous dispersion by using a low-dispersion glass material that satisfies conditional expression (6). can be corrected to

If the corresponding value of conditional expression (6) of the variable magnification optical system of this embodiment is below the lower limit, the third lens group cannot have sufficient anomalous dispersion, and longitudinal chromatic aberration and spherical aberration are reduced. It becomes difficult to correct to In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (6) to 55.000. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (6) to 58.000, more preferably 60.000.

Moreover, it is desirable that the variable power optical system of this embodiment satisfy the following conditional expression (7).
(7) 1.100 < βFw < 2.500
however,
βFw: Lateral magnification of the focusing lens group in the wide-angle end state

Conditional expression (7) defines the lateral magnification of the focusing lens group in the wide-angle end state. By satisfying the conditional expression (7), the variable magnification optical system of the present embodiment can reduce the amount of movement of the focusing lens group during focusing, thereby miniaturizing the variable magnification optical system. can.

If the corresponding value of conditional expression (7) of the variable magnification optical system of this embodiment exceeds the upper limit, the amount of movement of the focusing lens group during focusing becomes large, making it difficult to reduce the size of the variable magnification optical system. becomes. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (7) to 2.000. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (7) to 1.800, more preferably 1.700.

On the other hand, if the corresponding value of conditional expression (7) of the variable-magnification optical system of this embodiment is below the lower limit, the amount of movement of the focusing lens group during focusing becomes small, making focus control difficult. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.200. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (7) to 1.250, more preferably 1.300.

Moreover, it is desirable that the variable magnification optical system of this embodiment satisfy the following conditional expression (8).
(8) 0.500 < f2fn/f2 < 1.100
however,
f2fn: focal length of the most object side lens component in the second lens group f2: focal length of the second lens group

Conditional expression (8) defines the ratio between the focal length of the lens component closest to the object in the second lens group and the focal length of the second lens group. By satisfying the conditional expression (8), the variable power optical system of the present embodiment can appropriately arrange the power of the lens component closest to the object side in the second lens group. Various aberrations can be satisfactorily corrected.

When the corresponding value of conditional expression (8) of the variable-magnification optical system of this embodiment exceeds the upper limit, the refractive power of the lens component closest to the object in the second lens group becomes small, and spherical aberration and other various problems occur. It becomes difficult to correct aberration satisfactorily. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (8) to 1.000. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (8) to 0.900, more preferably 0.850.

On the other hand, if the corresponding value of conditional expression (8) of the variable-magnification optical system of this embodiment is below the lower limit, the refractive power of the lens component closest to the object side in the second lens group increases, causing spherical aberration and other problems. It becomes difficult to satisfactorily correct various aberrations that occur. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.550. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (8) to 0.600, more preferably 0.650.

Moreover, it is desirable that the variable magnification optical system of this embodiment satisfy the following conditional expression (9).
(9) 0.300<|fF|/ft<1.000
however,
fF: focal length of the focusing lens group ft: focal length of the variable magnification optical system in the telephoto end state

Conditional expression (9) defines the ratio between the focal length of the focusing lens group and the focal length of the variable magnification optical system in the telephoto end state. By satisfying conditional expression (9), the variable magnification optical system of this embodiment suppresses fluctuations in various aberrations including spherical aberration when focusing from an object at infinity to a close object. It is possible to reduce the size of the magnification optical system and the lens barrel.

When the corresponding value of conditional expression (9) of the variable-magnification optical system of this embodiment exceeds the upper limit, the refractive power of the focusing lens group becomes small, and various problems occur during focusing from an infinity object to a short distance object. It becomes difficult to satisfactorily correct aberration variations, particularly spherical aberration variations. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.900. In order to further ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (9) to 0.800, more preferably 0.750.

On the other hand, if the corresponding value of conditional expression (9) of the variable-magnification optical system of this embodiment is below the lower limit, the refractive power of the focusing lens group increases, and when focusing from an infinity object to a close object, It becomes difficult to satisfactorily correct fluctuations in various aberrations, particularly fluctuations in spherical aberration. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.400. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (9) to 0.500, more preferably 0.550.

Moreover, it is desirable that the variable magnification optical system of this embodiment satisfy the following conditional expression (10).
(10) 40.00° < ωw < 85.00°
however,
ωw: Half angle of view of the variable magnification optical system in the wide-angle end state

Conditional expression (10) defines the half angle of view of the variable magnification optical system in the wide-angle end state. By satisfying conditional expression (10), the variable power optical system of the present embodiment can satisfactorily correct various aberrations such as coma, distortion, and curvature of field while maintaining a wide angle of view. .

If the corresponding value of conditional expression (10) of the variable power optical system of this embodiment exceeds the upper limit, the angle of view becomes too wide, and various aberrations such as coma, distortion, and curvature of field cannot be satisfactorily corrected. becomes difficult. In order to ensure the effect of this embodiment, it is preferable to set the upper limit of conditional expression (10) to 84.00°. In order to further ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (10) to 83.00°, more preferably 82.00°.

On the other hand, if the corresponding value of conditional expression (10) of the variable-magnification optical system of this embodiment falls below the lower limit, the angle of view becomes narrow, making it difficult to satisfactorily correct various aberrations. In order to ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (10) to 41.00°. In order to further ensure the effect of this embodiment, it is preferable to set the lower limit of conditional expression (10) to 42.00°, more preferably 43.00°.

Also, in the variable power optical system of this embodiment, the subsequent lens group has a fourth lens group having negative refractive power and a fifth lens group having positive refractive power, and the fourth lens group is focused. It is desirable to have lens groups. With this configuration, the variable power optical system according to the present embodiment can reduce the size and weight of the focusing lens group, and as a result, the size of the variable power optical system and the lens barrel can be reduced.

The optical device of the present embodiment has the variable power optical system having the configuration described above. As a result, it is possible to realize an optical device that is small but can be adapted to a large imaging device, and that can satisfactorily correct various aberrations during zooming and focusing.

The method of manufacturing the variable magnification optical system of the present embodiment includes, in order from the object side, a first lens group having positive refractive power, a second lens group having negative refractive power, and a third lens group having positive refractive power. A method for manufacturing a variable power optical system having a lens group and a subsequent lens group having negative refractive power, wherein the first lens group and the second lens are adjusted during zooming from a wide-angle end state to a telephoto end state. the distance between the lens groups changes, the distance between the second lens group and the third lens group changes, the distance between the third lens group and the subsequent lens group changes, and The lens group or the subsequent lens group has a focusing lens group that moves when focusing from an infinity object to a close object, and satisfies the following conditional expressions (1) and (2): It is a manufacturing method of the variable-magnification optical system which comprises. As a result, it is possible to manufacture a variable-power optical system that is compact but can be adapted to a large-sized imaging device, and that can satisfactorily correct various aberrations during zooming and focusing.
(1) 2.00 < f1/fw < 8.000
(2) 0.400<BFw/fw<1.300
however,
f1: focal length of the first lens group fw: focal length of the variable power optical system in the wide-angle end state BFw: back focus (air conversion length) of the variable power optical system in the wide-angle end state
fw: focal length of the variable magnification optical system in the wide-angle end state

A variable magnification optical system according to numerical examples of the present embodiment will be described below with reference to the accompanying drawings.
(First embodiment)
1A, 1B, and 1C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable power optical system according to Example 1 of the present embodiment. The arrows under each lens group in FIG. 1A indicate the moving direction of each lens group during zooming from the wide-angle end state to the intermediate focal length state. The arrows under each lens group in FIG. 1B indicate the locus of movement of each lens group during zooming from the intermediate focal length state to the telephoto end state.

The variable power optical system according to this embodiment includes, in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S , a third lens group G3 having positive refractive power, and a subsequent lens group GR having negative refractive power.

The first lens group G1 is composed of, in order from the object side along the optical axis, a cemented lens constructed by cementing 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.
The second lens group G2 is composed of, in order from the object side along the optical axis, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave negative lens L22, and a biconvex positive lens L23. The negative meniscus lens L21 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical surfaces.
The third lens group G3 includes, in order from the object side along the optical axis, a biconvex positive lens L31, a positive meniscus lens L32 with a concave surface facing the object side, and a negative meniscus lens L33 with a concave surface facing the object side. and a cemented lens of a negative meniscus lens L34 having a convex surface facing the object side and a biconvex positive lens L35. The biconvex positive lens L31 is a glass-molded aspherical lens having an aspherical surface on the object side.

The subsequent lens group GR includes, in order from the object side along the optical axis, a fourth lens group G4 having negative refractive power, a fifth lens group G5 having positive refractive power, and a sixth lens group G5 having negative refractive power. and a lens group G6.
The fourth lens group G4 is composed of a negative meniscus lens L41 having a convex surface facing the object side. The negative meniscus lens L41 is a glass mold aspherical lens having an aspherical lens surface on the image plane I side.
The fifth lens group G5 is composed of a biconvex positive lens L51. The biconvex positive lens L51 is a glass-molded aspherical lens having an aspherical lens surface on the image plane I side.
The sixth lens group G6 is composed of, in order from the object side along the optical axis, a positive meniscus lens L61 having a concave surface facing the object side, and a biconcave negative lens L62.

Between the sixth lens group G6 and the image plane I, a filter FL such as a low-pass filter is arranged.
An imaging device (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I. FIG.

The variable-magnification optical system according to the present embodiment has a distance between the first lens group G1 and the second lens group G2, and a distance between the second lens group G2 and the third lens group G3 during zooming from the wide-angle end state to the telephoto end state. , the distance between the third lens group G3 and the fourth lens group G4, the distance between the fourth lens group G4 and the fifth lens group G5, and the distance between the fifth lens group G5 and the sixth lens group G6. , all the lens groups from the first lens group G1 to the sixth lens group G6 move along the optical axis. Further, the aperture diaphragm S moves integrally with the third lens group G3 during zooming from the wide-angle end state to the telephoto end state.
In the variable-magnification optical system according to the present embodiment, the fourth lens group G4 as a focusing lens group is moved along the optical axis in the direction of the image plane I, thereby focusing from an infinity object to a close object. .

Table 1 below lists the values of the specifications of the variable magnification optical system according to this example.
In [surface data], m is the order of the optical surfaces counted from the object side, r is the radius of curvature, d is the surface distance (the distance between the nth surface (n is an integer) and the n+1th surface), and nd is the d line ( νd indicates the Abbe number for the d-line (wavelength 587.6 nm), respectively. Also, OP indicates an object plane, Dn (n is an integer) a variable surface interval, S an aperture stop, and I an image plane. Note that the radius of curvature r=∞ indicates a plane. 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 paraxial radius of curvature is shown in the column of radius of curvature r.

In [various data], f is the focal length, FNo is the F number, ω is the half angle of view (unit is “°”), Y is the maximum image height, and TL is the total length of the variable magnification optical system according to the present embodiment, that is, the first The distances on the optical axis from surface 1 to image plane I are shown. BF is the back focus, that is, the distance on the optical axis from the lens surface closest to the image side to the image plane I, and BF (air conversion length) is the distance on the optical axis from the lens surface closest to the image side to the image plane I. , are values measured with optical blocks such as filters removed from the optical path. W indicates the wide-angle end state, M indicates the intermediate focal length state, and T indicates the telephoto end state.
[Lens Group Data] shows the starting surface number ST and focal length f of each lens group.

[Aspheric surface data] shows the aspheric surface coefficient and conic constant when the shape of the aspheric surface shown in [Surface data] is expressed by the following equation.
x=(h ² /r)/[1+{1−κ(h/r) ² } ^1/2 ]
+ ^A4h4 + ^A6h6 + ^A8h8 + ^A10h10
Here, h is the height in the direction perpendicular to the optical axis, x is the sag amount which is the distance along the optical axis from the tangent plane of the apex of the aspherical surface to the aspherical surface at height h, and κ is the conic constant. , A4, A6, A8, and A10 are the aspheric coefficients, and r is the paraxial radius of curvature of the reference sphere. Note that "En" (n is an integer) indicates "x10 ^-n ", for example "1.234E-05" indicates " ^1.234x10-5 ". The second-order aspheric coefficient A2 is 0 and is omitted.

In [Variable distance data], Dn (n is an integer) indicates the surface distance between the n-th surface and the (n+1)-th surface. W is the wide-angle end state, M is the intermediate focal length state, T is the telephoto end state, infinity is when focusing on an infinite distance object, and short distance is when focusing on a short distance object.
[Value corresponding to conditional expression] shows the corresponding value for each conditional expression.

Here, the unit of focal length f, radius of curvature r, and other lengths described in Table 1 is generally "mm". However, the optical system is not limited to this because equivalent optical performance can be obtained even if it is proportionally enlarged or proportionally reduced.
Note that the reference numerals in Table 1 described above are also used in the tables of the embodiments described later.

(Table 1) First embodiment [Surface data]
m r d nd νd
OP ∞
1 55.56269 2.090 1.84666 23.8
2 40.07848 8.659 1.75500 52.3
3 165.87769 D3

*4 305.23816 2.000 1.83357 41.5
*5 15.91291 8.769
6 -46.53317 1.500 1.49782 82.6
7 47.28615 0.150
8 36.78652 3.869 2.00060 25.5
9-4410.95550 D9

10(S) ∞ 1.500
*11 25.50000 5.056 1.61881 63.9
12 -55.83871 1.974
13 -29.70567 2.979 1.75500 52.3
14 -17.48858 1.500 1.91435 31.0
15 -26.37061 0.150
16 30.89509 1.500 1.95375 32.3
17 13.37829 4.608 1.59848 57.2
18-117.59347 D18

19 297.46406 1.500 1.55332 71.7
*20 20.53630 D20

21 143.35194 6.018 1.55332 71.7
*22 -24.59285 D22

23 -42.73323 4.479 1.84666 23.8
24 -25.30641 0.331
25 -31.61248 1.500 1.85026 32.4
26 200.00000 D26

27 ∞ 1.500 1.51680 64.1
28∞D28
I ∞

[Various data]
Zoom ratio: 2.75
WMT
f 24.72 46.30 67.90
FNo 4.00 4.25 4.00
ω 43.4 24.3 17.0
Y 21.70 21.70 21.70
TL 116.068 129.674 144.273
BF 15.310 32.587 40.396
BF (air conversion length) 14.799 32.076 39.885

[Lens group data]
Lens group ST f
1st lens group 1 113.52
2nd lens group 4 -25.53
3rd lens group 10 23.75
4th lens group 19 -39.94
5th lens group 21 38.43
6th lens group 23 -57.87

[Aspheric data]
Face κ A4 A6 A8 A10
4 1.00000e+00 6.25659e-06 -1.91556e-08 2.52781e-11 -1.35238e-14
5 0.00000e+00 2.80706e-05 6.07832e-08 -2.35463e-11 1.70671e-13
11 1.00000e+00 -1.67018e-05 -1.56513e-09 3.10565e-12 -5.19087e-13
20 1.00000e+00 4.64472e-06 -7.82369e-08 6.72266e-10 -6.64718e-12
22 1.00000e+00 1.52142e-05 -5.80147e-09 -8.01313e-12 3.24010e-14

[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D3 2.000 16.335 29.807 2.000 16.335 29.807
D9 21.355 7.927 2.222 21.355 7.927 2.222
D18 1.630 1.662 1.111 3.282 5.509 8.035
D20 9.084 9.053 9.604 7.433 5.205 2.680
D22 6.556 1.978 1.000 6.556 1.978 1.000
D26 13.711 30.988 38.797 13.711 30.988 38.797
D28 0.100 0.099 0.099 0.100 0.099 0.099

[Value corresponding to conditional expression]
(1) f1/fw = 4.5920
(2) BFw/fw = 0.5987
(3) 1/βRw = 0.7639
(4) f1/f1Rw = 5.4336
(5) nd3fp = 1.6188
(6) νd3p = 63.8544
(7) βFw = 2.4956
(8) f2 fn/f2 = 0.7915
(9) |fF|/ft = 0.5882
(10) ωw = 43.4511°

2A, 2B, and 2C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the first embodiment, respectively, when focusing on an object at infinity.
3A, 3B, and 3C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the first embodiment, respectively, when focusing on a short-distance object.

In each aberration diagram, FNO indicates the F-number, NA the numerical aperture, A the angle of incidence of rays, that is, the half angle of view (unit: "°"), and H0 the height of the object (unit: mm). In more detail, the spherical aberration chart shows the value of the F number FNO or numerical aperture NA corresponding to the maximum aperture, the astigmatism chart and the distortion chart show the maximum value of the half angle of view or object height, respectively, and the coma chart shows Indicates the value of each half angle of view or each object height. d indicates aberration at the d-line (wavelength: 587.6 nm), g indicates aberration at the g-line (wavelength: 435.8 nm), and those without d and g indicate aberration at the d-line. In the astigmatism diagrams, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. The coma diagram shows the coma or lateral aberration at each half angle of view or each object height. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

As can be seen from the aberration diagrams, the variable power optical system according to this 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 they have excellent imaging performance.

(Second embodiment)
4A, 4B, and 4C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable magnification optical system according to Example 2 of the present embodiment. The arrow under each lens group in FIG. 4A indicates the moving direction of each lens group during zooming from the wide-angle end state to the intermediate focal length state. The arrows under each lens group in FIG. 4B indicate the locus of movement of each lens group during zooming from the intermediate focal length state to the telephoto end state.

The variable power optical system according to this embodiment includes, in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S , a third lens group G3 having positive refractive power, and a subsequent lens group GR having negative refractive power.

The first lens group G1 is composed of, in order from the object side along the optical axis, a cemented lens constructed by cementing 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.
The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, and a positive meniscus lens L23 with a convex surface facing the object side. Consists of The negative meniscus lens L21 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical surfaces.
The third lens group G3 includes, in order from the object side along the optical axis, a positive meniscus lens L31 having a convex surface facing the object side, a positive meniscus lens L32 having a convex surface facing the object side, and a positive meniscus lens L32 having a convex surface facing the object side. It consists of a cemented lens of a positive meniscus lens L33 and a negative meniscus lens L34 having a convex surface facing the object side, and a biconvex positive lens L35. The positive meniscus lens L31 is a glass-molded aspherical lens having an aspherical surface on the object side. The biconvex positive lens L35 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical.

The succeeding lens group GR is composed of, in order from the object side along the optical axis, a fourth lens group G4 having negative refractive power and a fifth lens group G5 having positive refractive power.
The fourth lens group G4 is composed of a negative meniscus lens L41 having a convex surface facing the object side. The negative meniscus lens L41 is a glass-molded aspherical lens having an aspherical surface on the object side.
The fifth lens group G5 is composed of a positive meniscus lens L51 having a concave surface facing the object side.

Between the fifth lens group G5 and the image plane I, a filter FL such as a low-pass filter is arranged.
An imaging device (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I. FIG.

The variable-magnification optical system according to the present embodiment has a distance between the first lens group G1 and the second lens group G2, and a distance between the second lens group G2 and the third lens group G3 during zooming from the wide-angle end state to the telephoto end state. , the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5. , the third lens group G3 and the fourth lens group G4 move along the optical axis. At this time, the position of the fifth lens group G5 with respect to the image plane I is fixed. Further, the aperture diaphragm S moves integrally with the third lens group G3 during zooming from the wide-angle end state to the telephoto end state.
In the variable-magnification optical system according to the present embodiment, the positive lens L35 of the third lens group G3 as a focusing lens group is moved along the optical axis toward the object, thereby focusing from an infinity object to a short distance object. I do.
Table 2 below shows the values of the specifications of the variable-magnification optical system according to this example.

(Table 2) Second embodiment [Surface data]
m r d nd νd
OP ∞
1 80.37239 2.191 1.84666 23.8
2 51.98777 8.571 1.75500 52.3
3 2070.67650 D3

*4 641.99827 2.000 1.85135 40.1
*5 16.81311 8.912
6 -42.25332 1.500 1.49782 82.6
7 110.99976 0.132
8 41.80583 3.451 2.00069 25.5
9 1058.33950 D9

10(S) ∞ 1.500
*11 39.00831 2.770 1.49710 81.5
12 140.27569 0.100
13 43.60704 3.000 1.85896 22.7
14 289.56516 0.100
15 18.65400 3.904 1.49782 82.6
16 75.27582 1.500 1.85896 22.7
17 16.91540 7.449
*18 23.17679 5.123 1.49710 81.5
*19 -24.33043 D19

*20 99.02941 1.500 1.74330 49.3
21 22.73753 D21

22 -272.28910 4.264 1.48749 70.3
23 -65.54087 16.319
24 ∞ 1.500 1.51680 64.1
25 ∞ D25
I ∞

[Various data]
Zoom ratio: 2.75
WMT
f 24.72 46.31 67.90
FNo 4.00 4.00 4.00
ω 43.4 23.6 16.5
Y 21.70 21.70 21.70
TL 115.511 129.313 146.760
BF 17.920 17.921 17.921
BF (air conversion length) 17.409 17.410 17.410

[Lens group data]
Lens group ST f
1st lens group 1 118.36
2nd lens group 4 -26.19
Third lens group 10 24.69
4th lens group 20 -40.04
5th lens group 22 175.88

[Aspheric data]
Face κ A4 A6 A8 A10
4 1.00000e+00 4.80528e-06 -2.54101e-08 4.94759e-11 -4.51789e-14
5 0.00000e+00 2.73459e-05 3.32316e-08 9.23524e-12 -2.12635e-13
11 1.00000e+00 -5.44666e-06 -6.91574e-09 -1.69497e-11 3.80992e-13
18 1.00000e+00 -2.14682e-05 1.69238e-07 -7.34656e-11 -4.73585e-12
19 1.00000e+00 2.20572e-05 1.07214e-07 3.49803e-10 -7.90497e-12
20 1.00000e+00 4.65831e-07 4.17596e-08 -6.57210e-10 0.00000e+00

[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D3 2.000 18.199 30.446 2.000 18.199 30.446
D9 22.008 6.706 1.701 22.008 6.706 1.701
D19 3.665 3.116 1.770 4.734 6.005 7.453
D21 11.952 25.405 36.955 11.952 25.405 36.955
D25 0.101 0.102 0.102 0.101 0.102 0.102

[Value corresponding to conditional expression]
(1) f1/fw = 4.7877
(2) BFw/fw = 0.7042
(3) 1/βRw = 1.1035
(4) f1/f1Rw = 5.5459
(5) nd3fp = 1.4971
(6) νd3p = 81.5584
(7) βFw = -0.0053
(8) f2 fn/f2 = 0.7755
(9) |fF|/ft = 0.3645
(10) ωw = 43.4244°

5A, 5B, and 5C are diagrams of various aberrations in 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 an object at infinity.
6A, 6B, and 6C are diagrams of various aberrations in 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 a short-distance object.

As can be seen from the aberration diagrams, the variable power optical system according to this 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 they have excellent imaging performance.

(Third embodiment)
7A, 7B, and 7C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable power optical system according to Example 3 of the present embodiment. The arrow under each lens group in FIG. 7A indicates the moving direction of each lens group during zooming from the wide-angle end state to the intermediate focal length state. The arrows under each lens group in FIG. 7B indicate the locus of movement of each lens group during zooming from the intermediate focal length state to the telephoto end state.

The variable power optical system according to this embodiment includes, in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S , a third lens group G3 having positive refractive power, and a subsequent lens group GR having negative refractive power.

The first lens group G1 is composed of, in order from the object side along the optical axis, a cemented lens constructed by cementing 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.
The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 with a convex surface facing the object side, a biconcave negative lens L22, and a positive meniscus lens L23 with a convex surface facing the object side. Consists of The negative meniscus lens L21 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical surfaces.
The third lens group G3 includes, in order from the object side along the optical axis, a positive meniscus lens L31 having a convex surface facing the object side, a biconvex positive lens L32, a biconvex positive lens L33, and a biconcave lens. and a biconvex positive lens L35. The positive meniscus lens L31 is a glass-molded aspherical lens having an aspherical surface on the object side. The biconvex positive lens L35 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical.

The subsequent lens group GR is composed of, in order from the object side along the optical axis, a fourth lens group G4 having negative refractive power and a fifth lens group G5 having negative refractive power.
The fourth lens group G4 is composed of a positive meniscus lens L41 having a concave surface facing the object side and a biconcave negative lens L42. The biconcave negative lens L42 is a glass molded aspherical lens in which the object side lens surface and the image plane I side lens surface are aspherical.
The fifth lens group G5 is composed of a negative meniscus lens L51 having a concave surface facing the object side.

Between the fifth lens group G5 and the image plane I, a filter FL such as a low-pass filter is arranged.
An imaging device (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I. FIG.

The variable-magnification optical system according to the present embodiment has a distance between the first lens group G1 and the second lens group G2, and a distance between the second lens group G2 and the third lens group G3 during zooming from the wide-angle end state to the telephoto end state. , the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5. , the third lens group G3 and the fourth lens group G4 move along the optical axis. At this time, the position of the fifth lens group G5 with respect to the image plane I is fixed. Further, the aperture diaphragm S moves integrally with the third lens group G3 during zooming from the wide-angle end state to the telephoto end state.
In the variable-magnification optical system according to the present embodiment, the fourth lens group G4 as a focusing lens group is moved along the optical axis in the direction of the image plane I, thereby focusing from an infinity object to a close object. .
Table 3 below shows the values of the specifications of the variable magnification optical system according to this example.

(Table 3) Third embodiment [Surface data]
m r d nd νd
OP ∞
1 89.76586 2.265 1.91255 19.4
2 66.23033 7.686 1.72916 54.6
3 2195.99100 D3

*4 277.38836 2.000 1.88079 37.3
*5 17.49175 8.770
6 -57.48461 1.500 1.49782 82.6
7 51.02263 0.150
8 35.06470 4.055 2.04370 27.2
9 245.04447 D9

10(S) ∞ 1.500
*11 26.08134 2.954 1.49710 81.5
12 64.38198 0.150
13 42.81458 3.000 1.85896 22.7
14 -408.89472 1.730
15 33.86607 4.307 1.49782 82.6
16 -67.66664 1.500 1.85896 22.7
17 20.59315 3.307
*18 24.88849 5.009 1.49710 81.5
*19 -20.31236 D19

20 -55.34887 2.804 1.92119 24.0
21 -30.11397 1.627
*22 -37.35916 1.500 1.79864 45.4
*23 56.50097 D23

24 -115.79135 1.614 1.48749 70.3
25 -121.94772 13.000
26 ∞ 1.500 1.51680 64.1
27 ∞ D27
I ∞

[Various data]
Zoom ratio: 2.75
WMT
f 24.72 46.31 67.90
FNo 4.00 4.00 4.00
ω 43.5 23.5 16.4
Y 21.70 21.70 21.70
TL 116.411 128.891 146.759
BF 14.601 14.601 14.601
BF (air conversion length) 14.089 14.090 14.090

[Lens group data]
Lens group ST f
1st lens group 1 140.58
2nd lens group 4 -27.73
Third lens group 10 25.37
4th lens group 20 -47.81
5th lens group 24 -5147.18

[Aspheric data]
Face κ A4 A6 A8 A10
4 1.00000e+00 8.89487e-06 -5.32351e-08 1.15340e-10 -9.61968e-14
5 0.00000e+00 3.06664e-05 4.19740e-08 -3.78170e-10 1.10549e-12
11 1.00000e+00 -1.43493e-05 -1.64931e-08 -1.16757e-10 5.06940e-13
18 1.00000e+00 -5.15936e-06 -8.80397e-08 2.04540e-09 -5.99297e-12
19 1.00000e+00 3.60122e-05 -1.84722e-07 2.16592e-09 -2.51269e-12
22 1.00000e+00 3.47799e-05 -5.63856e-07 5.11223e-09 -2.14413e-11
23 1.00000e+00 4.08762e-05 -4.22039e-07 3.84567e-09 -1.33757e-11

[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D3 2.000 21.368 35.662 2.000 21.368 35.662
D9 25.688 8.326 2.837 25.688 8.326 2.837
D19 3.296 3.360 1.742 5.189 7.744 8.532
D23 13.398 23.808 34.489 11.505 19.424 27.699
D27 0.101 0.101 0.101 0.101 0.101 0.101

[Value corresponding to conditional expression]
(1) f1/fw = 5.6876
(2) BFw/fw = 0.5699
(3) 1/βRw = 0.9927
(4) f1/f1Rw = 6.3490
(5) nd3fp = 1.4971
(6) νd3p = 81.5584
(7) βFw = 1.5940
(8) f2 fn/f2 = 0.7670
(9) |fF|/ft = 0.7042
(10) ωw = 43.4653°

8A, 8B, and 8C are diagrams of various aberrations when focusing on an object at infinity 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.
9A, 9B, and 9C are diagrams of various aberrations 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, when focusing on a short-distance object.

As can be seen from the aberration diagrams, the variable power optical system according to this 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 they have excellent imaging performance.

(Fourth embodiment)
10A, 10B, and 10C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable magnification optical system according to Example 4 of the present embodiment. The arrow under each lens group in FIG. 10A indicates the moving direction of each lens group during zooming from the wide-angle end state to the intermediate focal length state. The arrows under each lens group in FIG. 10B indicate the locus of movement of each lens group during zooming from the intermediate focal length state to the telephoto end state.

The variable power optical system according to this embodiment includes, in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S , a third lens group G3 having positive refractive power, and a subsequent lens group GR having negative refractive power.

The first lens group G1 is composed of, in order from the object side along the optical axis, a cemented lens constructed by cementing 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.
The second lens group G2 is composed of, in order from the object side along the optical axis, a biconcave negative lens L21, a biconcave negative lens L22, and a biconvex positive lens L23. The biconcave negative lens L21 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical.
The third lens group G3 includes, in order from the object side along the optical axis, a positive meniscus lens L31 having a convex surface facing the object side, a biconvex positive lens L32, a biconvex positive lens L33, and a biconcave lens. and a biconvex positive lens L35. The positive meniscus lens L31 is a glass-molded aspherical lens having an aspherical surface on the object side. The biconvex positive lens L35 is a glass-molded aspherical lens in which the lens surface on the object side and the lens surface on the image plane I side are aspherical.

The trailing lens group GR consists of a fourth lens group G4 having negative refractive power.
The fourth lens group G4 is composed of a biconvex positive lens L41 and a biconcave negative lens L42. The biconcave negative lens L42 is a glass-molded aspherical lens having an aspherical lens surface on the image plane I side.

Between the fourth lens group G4 and the image plane I, a filter FL such as a low-pass filter is arranged.
An imaging device (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I. FIG.

The variable-magnification optical system according to the present embodiment has a distance between the first lens group G1 and the second lens group G2, and a distance between the second lens group G2 and the third lens group G3 during zooming from the wide-angle end state to the telephoto end state. and the distance between the third lens group G3 and the fourth lens group G4 change along the optical axis. Further, the aperture diaphragm S moves integrally with the third lens group G3 during zooming from the wide-angle end state to the telephoto end state.
In the variable-magnification optical system according to the present embodiment, the fourth lens group G4 as a focusing lens group is moved along the optical axis in the direction of the image plane I, thereby focusing from an infinity object to a close object. .
Table 4 below lists the values of the specifications of the variable magnification optical system according to this example.

(Table 4) Fourth embodiment [Surface data]
m r d nd νd
OP ∞
1 87.62477 2.150 1.84666 23.8
2 57.73166 8.600 1.75500 52.3
3 1380.47940 D3

*4 -252.60716 2.000 1.85135 40.1
*5 19.73259 11.312
6 -40.46779 1.500 1.49782 82.6
7 146.36804 0.100
8 64.01884 4.055 2.00100 29.1
9-126.68848 D9

10(S) ∞ 1.500
*11 30.22445 3.000 1.59201 67.0
12 51.27630 5.037
13 57.69494 3.000 1.85896 22.7
14 -45.14666 0.100
15 106.93037 4.300 1.49782 82.6
1 6 -30.19382 1.500 1.85896 22.7
17 23.72608 2.966
*18 23.40247 6.000 1.49710 81.5
*19 -18.45086 D19

20 757.78393 2.800 1.92119 24.0
21 -62.34786 0.172
22 -73.09604 1.500 1.80139 45.5
*23 26.98448 D23

24 ∞ 1.500 1.51680 64.1
25 ∞ D25
I ∞

[Various data]
Zoom ratio: 2.75
WMT
f 24.72 46.32 67.90
FNo 4.00 4.00 4.00
ω 44.8 24.2 16.7
Y 21.70 21.70 21.70
TL 123.661 134.611 154.520
BF 32.085 47.771 58.404
BF (air conversion length) 31.574 47.260 57.893

[Lens group data]
Lens group ST f
1st lens group 1 132.04
2nd lens group 4 -30.82
Third lens group 10 25.48
4th lens group 20 -41.00

[Aspheric data]
Face κ A4 A6 A8 A10
4 1.00000e+00 9.70747e-06 -3.52770e-08 6.58152e-11 -4.95165e-14
5 0.00000e+00 2.00742e-05 3.39646e-08 -2.35998e-10 6.14412e-13
11 1.00000e+00 -1.87683e-05 -3.17314e-08 -8.74929e-11 1.27393e-13
18 1.00000e+00 -2.29499e-05 -5.63341e-08 5.89446e-10 -2.45654e-12
19 1.00000e+00 2.51719e-05 -1.53372e-07 1.18933e-09 -4.11191e-12
23 1.00000e+00 -2.18656e-06 7.65289e-08 -5.83461e-10 2.30823e-12

[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D3 2.000 18.027 34.324 2.000 18.027 34.324
D9 24.453 5.483 0.100 24.453 5.483 0.100
D19 3.531 1.737 0.100 4.979 4.625 4.590
D23 30.484 46.169 56.802 29.035 43.281 52.312
D25 0.101 0.102 0.102 0.101 0.102 0.103
Conditional value]
(1) f1/fw = 5.3414
(2) BFw/fw = 1.2773
(3) 1/βRw = 0.5678
(4) f1/f1Rw = 6.0910
(5) nd3fp = 1.4971
(6) νd3p = 81.5584
(7) βFw = 1.7613
(8) f2 fn/f2 = 0.6952
(9) |fF|/ft = 0.6038
(10) ωw = 44.8000°

11A, 11B, and 11C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the fourth embodiment, respectively, when focusing on an object at infinity.
12A, 12B, and 12C are diagrams of various aberrations in the wide-angle end state, intermediate focal length state, and telephoto end state of the variable power optical system according to the fourth embodiment, respectively, when focusing on a close object.

As can be seen from the aberration diagrams, the variable power optical system according to this 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 they have excellent imaging performance.

(Fifth embodiment)
13A, 13B, and 13C are cross-sectional views in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the variable magnification optical system according to Example 5 of the present embodiment. The arrow under each lens group in FIG. 13A indicates the moving direction of each lens group during zooming from the wide-angle end state to the intermediate focal length state. The arrows under each lens group in FIG. 13B indicate the locus of movement of each lens group during zooming from the intermediate focal length state to the telephoto end state.

The variable power optical system according to this embodiment includes, in order from the object side along the optical axis, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, an aperture stop S , a third lens group G3 having positive refractive power, and a subsequent lens group GR having negative refractive power.

The first lens group G1 is composed of, in order from the object side along the optical axis, a cemented lens constructed by cementing a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12.
The second lens group G2 consists of, in order from the object side along the optical axis, a biconcave negative lens L21, a biconcave negative lens L22, and a positive meniscus lens L23 having a convex surface facing the object side. The biconcave negative lens L21 is a glass-molded aspherical lens having an aspherical lens surface on the image plane I side.
The third lens group G3 includes, in order from the object side along the optical axis, a biconvex positive lens L31, a biconvex positive lens L32, a biconvex positive lens L33, and a biconcave negative lens L34. and a biconvex positive lens L35. The biconvex positive lens L31 is a glass-molded aspherical lens having an aspherical surface on the object side. The biconvex positive lens L35 is a glass-molded aspherical lens having an aspherical surface on the object side.

The trailing lens group GR consists of a fourth lens group G4 having negative refractive power.
The fourth lens group G4 is composed of a biconvex positive lens L41 and a biconcave negative lens L42. The biconcave negative lens L42 is a glass-molded aspherical lens having an aspherical surface on the object side.

Between the fourth lens group G4 and the image plane I, a filter FL such as a low-pass filter is arranged.
An imaging device (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I. FIG.

The variable-magnification optical system according to the present embodiment has a distance between the first lens group G1 and the second lens group G2, and a distance between the second lens group G2 and the third lens group G3 during zooming from the wide-angle end state to the telephoto end state. and the distance between the third lens group G3 and the fourth lens group G4 change along the optical axis. Further, the aperture diaphragm S moves integrally with the third lens group G3 during zooming from the wide-angle end state to the telephoto end state.
In the variable-magnification optical system according to the present embodiment, the fourth lens group G4 as a focusing lens group is moved along the optical axis in the direction of the image plane I, thereby focusing from an infinity object to a close object. .
Table 5 below lists the values of the specifications of the variable magnification optical system according to this example.

(Table 5) Fifth embodiment [Surface data]
m r d nd νd
OP ∞
1 119.32600 2.150 1.84666 23.8
2 68.71728 8.600 1.75500 52.3
3-1041.56390 D3

4 -457.17100 2.000 1.85135 40.1
*5 20.61283 7.414
6 -71.55363 1.500 1.49782 82.6
7 108.27671 0.100
8 42.73022 4.055 2.00069 25.5
9 567.23839 D9

10(S) ∞ 1.500
*11 49.74902 2.954 1.55332 71.7
12 -831.68070 5.492
13 119.77899 3.000 1.86074 23.1
14 -32.91562 0.100
15 788.35305 4.307 1.49782 82.6
16 -22.05418 1.500 1.86074 23.1
17 30.00000 3.522
*18 41.01853 7.000 1.59201 67.0
19 -22.23377 D19

20 1063.64530 2.804 1.90200 25.3
21 -64.43734 3.021
*22 -73.11499 1.500 1.80139 45.5
23 30.53440 D23

24 ∞ 1.500 1.51680 64.1
25 ∞ D25
I ∞

[Various data]
Zoom ratio: 2.75
WMT
f 24.72 46.31 67.90
FNo 4.00 4.00 4.00
ω 43.3 22.1 15.4
Y 20.00 20.00 20.00
TL 116.346 132.760 149.927
BF 20.082 35.787 48.197
BF (air conversion length) 19.571 35.276 47.686

[Lens group data]
Lens group ST f
1st lens group 1 154.54
2nd lens group 4 -34.53
Third lens group 10 28.38
4th lens group 20 -48.62

[Aspheric data]
Face κ A4 A6 A8 A10
5 0.00000e+00 1.27904e-05 4.25474e-08 -1.06207e-10 3.28727e-13
11 1.00000e+00 -2.37429e-05 -4.66597e-09 -4.37585e-10 2.03678e-12
18 1.00000e+00 -1.38634e-05 3.10542e-08 -4.01477e-11 9.01450e-14
22 1.00000e+00 -4.04480e-06 -1.42432e-08 1.81173e-10 -7.62702e-13

[Variable interval data]
WMT WMT
Infinity Infinity Infinity Close Close Close
D3 2.000 23.094 37.212 2.000 23.094 37.212
D9 23.685 7.628 1.000 23.685 7.628 1.000
D19 8.059 3.733 1.000 9.929 6.663 5.153
D23 18.482 34.186 46.595 16.612 31.256 42.442
D25 0.101 0.101 0.102 0.101 0.101 0.102

[Value corresponding to conditional expression]
(1) f1/fw = 6.2515
(2) BFw/fw = 0.7917
(3) 1/βRw = 0.7392
(4) f1/f1Rw = 6.8464
(5) nd3fp = 1.5533
(6) νd3p = 71.6835
(7) βFw = 1.3529
(8) f2fn/f2 = 0.6696
(9) |fF|/ft = 0.7160
(10) ωw = 43.3000°

14A, 14B, and 14C are diagrams of various aberrations in 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 on an object at infinity.
15A, 15B, and 15C are diagrams of various aberrations in 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 on a close object.

As can be seen from the aberration diagrams, the variable power optical system according to this 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 they have excellent imaging performance.

According to each of the above-described embodiments, it is possible to cope with a large-sized image pickup device while being compact, to correct various aberrations from the wide-angle end state to the telephoto end state, and to achieve excellent results even when focusing on a short-distance object. A variable power optical system having image performance can be realized.

The variable power optical system according to the present embodiment has a variable power ratio of about 2 to 10 times, and a focal length in the wide-angle end state of about 20 to 30 mm in terms of 35 mm. Further, the variable power optical system according to the present embodiment has an F-number of about f/2.0 to f/4.5 in the wide-angle end state, and an F-number of about f/2.0 to f/4.5 in the telephoto end state. It is about 6.3.
Moreover, each of the above examples shows a specific example of the present embodiment, and the present embodiment is not limited to these. The following content can be appropriately adopted within a range that does not impair the optical performance of the variable power optical system of this embodiment.

Numerical examples of the variable-magnification optical system according to the present embodiment have shown four-group, five-group, or six-group configurations, but the present embodiment is not limited to this, and other group configurations (for example, seven groups, etc.) are shown. ) can also be configured. Specifically, a configuration in which a lens or lens group is added to the most object side or most image side of the variable power optical system of each of the above embodiments may be used. Alternatively, a lens or lens group may be added between the first lens group G1 and the second lens group G2. Alternatively, a lens or lens group may be added between the second lens group G2 and the third lens group G3. Alternatively, a lens or lens group may be added between the third lens group G3 and the subsequent lens group GR.

Further, in each of the above embodiments, the lens group constituting the subsequent lens group GR is the fourth lens group G4, or the fourth lens group G4 and the fifth lens group G5, or the fourth lens group G4, the fifth lens group G5 and the Although the sixth lens group G6 is shown, it is not limited to this.

Further, in each of the above embodiments, one lens group or part of the lens group is used as the focusing lens group, but two or more lens groups may be used as the focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by a motor for autofocus, such as an ultrasonic motor, a stepping motor, a VCM motor, or the like.

Further, in the variable power optical system of each of the above embodiments, any one of the lens groups in whole or in part may be moved as a vibration reduction group so as to include a component in the direction perpendicular to the optical axis, or the optical axis may be shifted. It is also possible to adopt a configuration in which vibration isolation is performed by rotationally moving (swinging) in an in-plane direction including.

Further, the lens surfaces of the lenses constituting the variable power optical system of each of the above embodiments may be spherical, planar, or aspherical. When the lens surface is spherical or flat, it is preferable because it facilitates lens processing and assembly adjustment, and can prevent deterioration of optical performance due to errors in lens processing and assembly adjustment. In addition, even when the image plane is shifted, deterioration in rendering performance is small, which is preferable. If the lens surface is aspherical, it can be aspherical by grinding, glass molded aspherical by molding glass into an aspherical shape, or composite aspherical by forming resin on the glass surface into an aspherical shape. good. Further, the lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In the variable power optical system of each of the above embodiments, the aperture stop S is preferably arranged between the second lens group G2 and the third lens group G3. may be substituted for the role.

Further, an antireflection film having a high transmittance in a wide wavelength range may be applied to the lens surfaces of the lenses constituting the variable power optical system of each of the above embodiments. As a result, flare and ghost can be reduced, and high contrast and high optical performance can be achieved.

Next, a camera provided with the variable-magnification optical system of this embodiment will be described with reference to FIG.
FIG. 16 is a diagram showing the configuration of a camera provided with the variable-magnification optical system of this embodiment.
As shown in FIG. 16, the camera 1 is a so-called mirrorless camera of an interchangeable lens type provided with the variable-magnification optical system according to the first embodiment as a photographing lens 2 .

In this camera 1, light from an unillustrated object (subject) is condensed by a photographing lens 2 and passed through an unillustrated OLPF (Optical low pass filter) onto an imaging surface of an imaging unit 3. to form an image of the subject. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3 to generate an image of the subject. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1 . This allows the photographer to observe the subject through the EVF4.
Also, when a release button (not shown) is pressed by the photographer, the image of the subject generated by the imaging section 3 is stored in a memory (not shown). In this manner, the photographer can photograph the subject with the camera 1. FIG.

Here, the variable-magnification optical system according to the first embodiment mounted as the photographing lens 2 in the camera 1 has excellent optical performance as described above and is compact. In other words, this camera 1 can be made compact, and achieves excellent optical performance with excellent correction of various aberrations from the wide-angle end state to the telephoto end state, and excellent imaging performance even when focusing on a close object. can do. It should be noted that the same effect as that of the camera 1 can be obtained even if a camera having the variable power optical system according to the second to fifth embodiments as the photographing lens 2 is constructed. Further, even when the variable magnification optical system according to each of the above embodiments is mounted on a single-lens reflex type camera that has a quick return mirror and observes a subject through a finder optical system, the same effect as the camera 1 can be obtained. can.

Next, the outline of the manufacturing method of the variable-magnification optical system of this embodiment will be described with reference to FIG.
FIG. 17 is a flowchart showing an outline of the method for manufacturing the variable power optical system of this embodiment.

The method for manufacturing the variable magnification optical system of this embodiment shown in FIG. and a subsequent lens group having negative refractive power, the method including the following steps S1 to S3.

Step S1: During zooming from the wide-angle end state to the telephoto end state, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the third lens group changes. and the distance between the third lens group and the subsequent lens group is changed.
Step S2: Configure the third lens group or the subsequent lens group to have a focusing lens group that moves when focusing from an infinity object to a close object.
Step S3: Make the variable magnification optical system satisfy the following conditional expressions (1) and (2).
(1) 2.00 < f1/fw < 8.000
(2) 0.400<BFw/fw<1.300
however,
f1: focal length of the first lens group fw: focal length of the variable power optical system in the wide-angle end state BFw: back focus (air conversion length) of the variable power optical system in the wide-angle end state
fw: focal length of the variable magnification optical system in the wide-angle end state

According to the method for manufacturing a variable magnification optical system of the present embodiment, it is possible to cope with a large imaging device while being compact, to correct various aberrations well from the wide-angle end state to the telephoto end state, and to further improve the close-up. It is possible to realize a variable magnification optical system having high optical performance with excellent imaging performance even when focusing on a distance object.

G1 First lens group G2 Second lens group G3 Third lens group G4 Fourth lens group G5 Fifth lens group G6 Sixth lens group GR Subsequent lens group S Aperture diaphragm I Image plane

Claims (9)

In order from the object side, a first lens group with positive refractive power, a second lens group with negative refractive power, a third lens group with positive refractive power, and a subsequent lens group with negative refractive power. Consists of
Having a fourth lens group having a negative refractive power on the most object side of the subsequent lens group,
the subsequent lens group consists of one lens group, two lens groups, or three lens groups;
The first lens group consists of one lens component,
When zooming, the distance between adjacent lens groups changes,
the third lens group or the subsequent lens group has a focusing lens group that moves during focusing;
A variable magnification optical system that satisfies the following conditional expressions.
4.00 < f1/fw < 8.000
0.400<BFw/fw<1.300
however,
f1: focal length of the first lens group fw: focal length of the variable power optical system in the wide-angle end state 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 Focal length The second lens group has one positive lens,
2. The variable magnification optical system according to claim 1, wherein the fourth lens group has one negative lens. 3. A variable-magnification optical system according to claim 1, which satisfies the following conditional expression.
5.000<f1/f1Rw<9.000
however,
f1: focal length of the first lens group f1Rw: combined focal length in the wide-angle end state of the lens groups arranged closer to the image plane than the first lens group 4. The variable-magnification optical system according to claim 1, wherein the following conditional expression is satisfied.
0.500 < 1/βRw < 1.200
however,
βRw: Lateral magnification of the lens group closest to the image plane in the wide-angle end state 5. The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
1.100 < βFw < 2.500
however,
βFw: Lateral magnification of the focusing lens group in the wide-angle end state 6. The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
0.300 < |fF|/ft < 1.000
however,
fF: focal length of the focusing lens group ft: focal length of the variable magnification optical system in the telephoto end state 7. The variable magnification optical system according to claim 1, wherein the following conditional expression is satisfied.
40.00° < ωw < 85.00°
however,
ωw: Half angle of view of the variable magnification optical system in the wide-angle end state The subsequent lens group has a fourth lens group having negative refractive power and a fifth lens group having positive refractive power,
The variable magnification optical system according to any one of claims 1 to 7, wherein the fourth lens group has the focusing lens group. An optical apparatus comprising the variable magnification optical system according to any one of claims 1 to 8.

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