JP2022163900A - Zoom optical system, optical device, and method of manufacturing zoom optical system - Google Patents

Abstract

To provide a zoom optical system which is compact and yet offers good optical performance.SOLUTION: A zoom optical system ZL provided herein consists of a first lens group G1 having negative refractive power and a rear group GR comprising at least one lens group, and is configured such that distances between adjacent lens groups change while zooming. At least a part of a lens group belonging to the rear group GR is a focusing group GF with positive refractive power configured to move along an optical axis while focusing. The zoom optical system satisfies the following conditional expression: 0.50<ft/fF<10.00, where ft represents a focal length of the zoom optical system ZL at the telephoto end, and fF represents a focal length of the focusing group GF.SELECTED DRAWING: Figure 1

Description

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

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 such a variable-magnification optical system, it is difficult to obtain good optical performance while miniaturizing the system.

WO2020/012638

A variable magnification optical system according to a first aspect of the present invention comprises a first lens group having a negative refractive power and a rear group having at least one lens group arranged in order from the object side along an optical axis, During zooming, the spacing between adjacent lens groups changes, and at least a portion of any lens group in the at least one lens group of the rear group moves along the optical axis during focusing. It is a focusing group having a positive refractive power that satisfies the following conditional expression.
0.50<ft/fF<10.00
where ft is the focal length of the variable magnification optical system in the telephoto end state fF is the focal length of the focusing group

A variable magnification optical system according to a second aspect of the present invention comprises a first lens group having a negative refractive power and a rear group having at least one lens group arranged in order from the object side along an optical axis, During zooming, the spacing between adjacent lens groups changes, and at least a portion of any lens group in the at least one lens group of the rear group moves along the optical axis during focusing. It is a focusing group having a positive refractive power that satisfies the following conditional expression.
0.30<fw/fF<7.00
where fw is the focal length of the variable magnification optical system in the wide-angle end state, fF is the focal length of the focusing group

An optical apparatus according to the present invention includes the above variable magnification optical system.

A method for manufacturing a variable magnification optical system according to a first aspect of the present invention includes a first lens group having negative refractive power and a rear group having at least one lens group, which are arranged in order from the object side along an optical axis. In a method for manufacturing a variable magnification optical system comprising: at least a part of any lens group in the at least one lens group of the rear group, the distance between adjacent lens groups changing during zooming is a focusing group having positive refractive power that moves along the optical axis during focusing, and each lens is arranged in the lens barrel so as to satisfy the following conditional expression.
0.50<ft/fF<10.00
where ft is the focal length of the variable magnification optical system in the telephoto end state fF is the focal length of the focusing group

A method of manufacturing a variable magnification optical system according to a second aspect of the present invention comprises a first lens group having negative refractive power and a rear group having at least one lens group, which are arranged in order from the object side along the optical axis. In a method for manufacturing a variable magnification optical system comprising: at least a part of any lens group in the at least one lens group of the rear group, the distance between adjacent lens groups changing during zooming is a focusing group having positive refractive power that moves along the optical axis during focusing, and each lens is arranged in the lens barrel so as to satisfy the following conditional expression.
0.30<fw/fF<7.00
where fw is the focal length of the variable magnification optical system in the wide-angle end state, fF is the focal length of the focusing group

1 is a diagram showing a lens configuration of a variable power optical system according to a first example; FIG. FIGS. 2A and 2B are diagrams of various aberrations in the wide-angle end state and the telephoto end state of the variable power optical system according to the first embodiment, respectively, when focusing on infinity. FIG. 10 is a diagram showing a lens configuration of a variable-magnification optical system according to a second example; 4A and 4B are diagrams of various aberrations in the wide-angle end state and the telephoto end state of the variable power optical system according to the second embodiment, respectively, when focusing on infinity. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a third example; 6A and 6B are diagrams of various aberrations in the wide-angle end state and the telephoto end state of the variable power optical system according to the third embodiment, respectively, when focusing on infinity. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a fourth example; 8A and 8B are diagrams of various aberrations in the wide-angle end state and the telephoto end state of the variable power optical system according to the fourth embodiment, respectively, when focusing on infinity. FIG. 11 is a diagram showing a lens configuration of a variable-magnification optical system according to a fifth example; 10A and 10B are diagrams of various aberrations in the wide-angle end state and the telephoto end state of the variable power optical system according to the fifth embodiment, respectively, when focusing on infinity. It is a figure which shows the structure of the camera provided with the variable-magnification optical system which concerns on each embodiment. 4 is a flow chart showing a method of manufacturing a variable power optical system according to each embodiment.

Preferred embodiments of the present invention are described below. First, a camera (optical device) having a variable power optical system according to each embodiment will be described with reference to FIG. As shown in FIG. 11, this camera 1 comprises a main body 2 and a photographing lens 3 attached to the main body 2. As shown in FIG. The main body 2 includes an imaging device 4 , a main body control section (not shown) that controls the operation of the digital camera, and a liquid crystal screen 5 . The taking lens 3 includes a variable magnification optical system ZL consisting of a plurality of lens groups, and a lens position control mechanism (not shown) that controls the position of each lens group. The lens position control mechanism includes a sensor that detects the position of the lens group, a motor that moves the lens group back and forth along the optical axis, a control circuit that drives the motor, and the like.

Light from a subject is condensed by the variable-magnification optical system ZL of the photographing lens 3 and reaches the image plane I of the imaging device 4 . The light from the subject reaching the image plane I is photoelectrically converted by the imaging device 4 and recorded as digital image data in a memory (not shown). The digital image data recorded in the memory can be displayed on the liquid crystal screen 5 according to the user's operation. This camera may be a mirrorless camera or a single-lens reflex type camera having a quick return mirror. Also, the variable power optical system ZL shown in FIG. 11 schematically shows a variable power optical system provided in the photographing lens 3, and the lens configuration of the variable power optical system ZL is not limited to this configuration. do not have.

Next, a variable power optical system according to the first embodiment will be described. A variable power optical system ZL(1) as an example of the variable power optical system (zoom lens) ZL according to the first embodiment includes, as shown in FIG. It is composed of a first lens group G1 having refractive power and a rear group GR having at least one lens group. During zooming, the distance between adjacent lens groups changes. In at least one lens group of the rear group GR, at least part of any lens group moves along the optical axis during focusing and has a positive refractive power.
is F.

With the above configuration, the variable power optical system ZL according to the first embodiment satisfies the following conditional expression (1).
0.50<ft/fF<10.00 (1)
where ft is the focal length of the variable power optical system ZL in the telephoto end state fF is the focal length of the focusing group GF

According to the first embodiment, it is possible to obtain a variable power optical system that is compact and has excellent optical performance, and an optical apparatus that includes this variable power optical system. The variable-magnification optical system ZL according to the first embodiment may be the variable-magnification optical system ZL(2) shown in FIG. 3, the variable-magnification optical system ZL(3) shown in FIG. It may be the system ZL(4) or the variable power optical system ZL(5) shown in FIG.

Conditional expression (1) defines an appropriate relationship between the focal length of the variable magnification optical system ZL and the focal length of the focusing group GF in the telephoto end state. By satisfying conditional expression (1), it is possible to suppress variations in spherical aberration, coma, and curvature of field when focusing on a short-distance object while maintaining a small size.

If the corresponding value of conditional expression (1) is out of the above range, the amount of movement of the focusing group GF becomes large, resulting in spherical aberration, coma, and curvature of field when focusing on a short-distance object. It becomes difficult to control fluctuations. The upper limit of conditional expression (1) is 8.50, 7.00, 6.00, 5.00, 4.50, 4.00, 3.50, 3.00, 2.75, 2.50, By setting it to 2.25 and further to 2.00, the effect of this embodiment can be made more reliable. Further, the lower limit of conditional expression (1) is 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.90, 0.95, 1.00, 1. By setting it to 05 and further to 1.10, the effect of this embodiment can be made more reliable.

Next, a variable power optical system according to the second embodiment will be described. A variable power optical system ZL(1) as an example of a variable power optical system (zoom lens) ZL according to the second embodiment includes, as shown in FIG. It is composed of a first lens group G1 having refractive power and a rear group GR having at least one lens group. During zooming, the distance between adjacent lens groups changes. In at least one lens group of the rear group GR, at least part of any lens group is a focusing group GF having positive refractive power that moves along the optical axis during focusing.

With the above configuration, the variable power optical system ZL according to the second embodiment satisfies the following conditional expression (2).
0.30<fw/fF<7.00 (2)
where fw: focal length of variable-magnification optical system ZL in the wide-angle end state fF: focal length of focusing group GF

According to the second embodiment, it is possible to obtain a variable power optical system that is compact and has excellent optical performance, and an optical apparatus that includes this variable power optical system. The variable power optical system ZL according to the second embodiment may be the variable power optical system ZL(2) shown in FIG. 3, the variable power optical system ZL(3) shown in FIG. 5, or the variable power optical system ZL(3) shown in FIG. It may be the system ZL(4) or the variable power optical system ZL(5) shown in FIG.

Conditional expression (2) defines an appropriate relationship between the focal length of the variable magnification optical system ZL and the focal length of the focusing group GF in the wide-angle end state. By satisfying the conditional expression (2), it is possible to suppress fluctuations in spherical aberration, coma, and curvature of field when focusing on a short-distance object while maintaining a small size.

If the corresponding value of conditional expression (2) is out of the above range, the amount of movement of the focusing group GF becomes large, resulting in spherical aberration, coma, and curvature of field when focusing on a short-distance object. It becomes difficult to control fluctuations. The upper limit of conditional expression (2) is 6.00, 5.00, 4.50, 4.00, 3.50, 3.00, 2.75, 2.50, 2.25, 2.00, By setting it to 1.75, 1.50, and further 1.25, the effect of this embodiment can be made more reliable. Further, by setting the lower limit of conditional expression (2) to 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, and further to 0.65, The effect can be made more reliable.

In the variable-magnification optical system ZL according to the first and second embodiments, at least one lens group of the rear group GR is a second lens group having positive refractive power disposed closest to the object side of the rear group GR. It is desirable to include G2 and satisfy the following conditional expression (3).
1.30<f2/(-X2)<2.50 (3)
where f2 is the focal length of the second lens group G2 X2 is the amount of movement of the second lens group G2 during zooming from the wide-angle end state to the telephoto end state (the amount of movement toward the image side is a positive value)

Conditional expression (3) defines an appropriate relationship between the focal length of the second lens group G2 and the amount of movement of the second lens group G2 during zooming from the wide-angle end state to the telephoto end state. . By satisfying the conditional expression (3), it is possible to satisfactorily correct various aberrations while maintaining a small size.

If the corresponding value of conditional expression (3) is out of the above range, it becomes difficult to correct various aberrations while miniaturizing the variable-magnification optical system ZL. By setting the upper limit of conditional expression (3) to 2.40, 2.30, 2.25, 2.20, 2.15, 2.10, and further to 2.05, the effect of each embodiment is can be made more secure. By setting the lower limit of conditional expression (3) to 1.33, 1.35, 1.38, 1.40, and further to 1.43, the effect of each embodiment is made more reliable. be able to.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (4).
1.00<βRt/βRw<2.25 (4)
where βRt: lateral magnification of the rear group GR in the telephoto end state βRw: lateral magnification of the rear group GR in the wide-angle end state

Conditional expression (4) defines an appropriate relationship between the lateral magnification of the rear group GR in the telephoto end state and the lateral magnification of the rear group GR in the wide-angle end state. By satisfying conditional expression (4), it is possible to suppress variations in spherical aberration, coma, and curvature of field when focusing on a short-distance object while maintaining a small size.

If the corresponding value of conditional expression (4) is out of the above range, it becomes difficult to suppress fluctuations in spherical aberration, coma, and curvature of field when focusing on a short-distance object. By setting the upper limit of conditional expression (4) to 2.20, 2.10, 2.00, 1.95, 1.90, and further to 1.85, the effect of each embodiment is more reliable. can be Further, by setting the lower limit of conditional expression (4) to 1.05, 1.10, 1.15, 1.20, and further to 1.25, the effect of each embodiment is made more reliable. be able to.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (5).
0.30<(-fFRw)/fF<7.00 (5)
where fFRw is the focal length of a lens group composed of lenses arranged closer to the image side than the focusing group GF in the wide-angle end state

Conditional expression (5) defines an appropriate relationship between the focal length of the lens group composed of lenses arranged closer to the image side than the focusing group GF in the wide-angle end state and the focal length of the focusing group GF. It is. Hereinafter, a lens group composed of lenses arranged closer to the image side than the focusing group GF may be referred to as an image-side lens group GFR. By satisfying the conditional expression (5), it is possible to suppress variations in spherical aberration, coma, and curvature of field when focusing on a short-distance object while maintaining a small size.

If the corresponding value of conditional expression (5) exceeds the upper limit, the focal length of the focusing group GF becomes too short with respect to the focal length of the image-side lens group GFR. It becomes difficult to suppress variations in coma and curvature of field. The upper limit of conditional expression (5) is 6.00, 5.00, 4.50, 4.00, 3.50, 3.00, 2.75, 2.50, 2.25, 2.00, By setting it to 1.75, 1.50, and further 1.30, the effect of each embodiment can be made more reliable.

When the corresponding value of conditional expression (5) is below the lower limit, the amount of movement of the focusing group GF becomes large, so that fluctuations in spherical aberration, coma, and curvature of field when focusing on a short-distance object are suppressed. difficult to suppress. The lower limit of conditional expression (5) is 0.40, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, Furthermore, by setting it to 0.95, the effect of each embodiment can be made more reliable.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (6).
0.30<(-fFRt)/fF<7.00 (6)
where fFRt is the focal length of a lens group composed of lenses arranged closer to the image side than the focusing group GF in the telephoto end state

Conditional expression (6) defines the focal length of a lens group (image-side lens group GFR) composed of lenses arranged closer to the image side than the focusing group GF in the telephoto end state, and the focal length of the focusing group GF. It stipulates the appropriate relationship between By satisfying conditional expression (6), it is possible to suppress variations in spherical aberration, coma, and curvature of field when focusing on a short-distance object while maintaining a small size.

If the corresponding value of conditional expression (6) exceeds the upper limit, the focal length of the focusing group GF becomes too short with respect to the focal length of the image-side lens group GFR. It becomes difficult to suppress variations in coma and curvature of field. The upper limit of conditional expression (6) is 6.00, 5.00, 4.50, 4.00, 3.75, 3.50, 3.00, 3.25, 3.00, 2.75, By setting it to 2.50 and further to 2.25, the effect of each embodiment can be made more reliable.

When the corresponding value of conditional expression (6) is below the lower limit, the amount of movement of the focusing group GF becomes large, so that fluctuations in spherical aberration, coma, and curvature of field when focusing on a short-distance object are suppressed. difficult to suppress. The lower limit of conditional expression (6) is 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.05, 1.10, and further 1.15 , the effect of each embodiment can be made more reliable.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (7).
0.20<fRPF/fF<3.00 (7)
However, fRPF: the focal length of the lens group closest to the object side among at least one lens group of the rear group GR, which has positive refractive power.

Conditional expression (7) is an appropriate focal length between the focal length of the lens group closest to the object side among the lens groups having positive refractive power in at least one lens group of the rear group GR and the focal length of the focusing group GF. It defines the relationship. By satisfying conditional expression (7), it is possible to suppress variations in spherical aberration, coma, and curvature of field when focusing on a short-distance object while maintaining a small size.

When the corresponding value of conditional expression (7) exceeds the upper limit, the focal length of the focusing group GF becomes short, so that fluctuations in spherical aberration, coma, and curvature of field when focusing on a short-distance object are reduced. difficult to suppress. The upper limit of conditional expression (7) is 2.75, 2.50, 2.25, 2.00, 1.75, 1.50, 1.25, 1.00, 0.95, and further 0.90 , the effect of each embodiment can be made more reliable.

When the corresponding value of conditional expression (7) is below the lower limit, the focal length of the lens group closest to the object side among the lens groups having positive refractive power in the rear group GR becomes short, so that spherical aberration and coma are corrected. becomes difficult. By setting the lower limit of conditional expression (7) to 0.25, 0.30, 0.35, 0.40, and further to 0.45, the effect of each embodiment can be made more reliable. can.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (8).
0.15<fRw/fF<4.00 (8)
where fRw is the focal length of the rear group GR in the wide-angle end state

Conditional expression (8) defines an appropriate relationship between the focal length of the rear group GR and the focal length of the focusing group GF in the wide-angle end state. By satisfying conditional expression (8), it is possible to satisfactorily correct various aberrations while maintaining a compact size.

If the corresponding value of conditional expression (8) exceeds the upper limit, it becomes difficult to correct various aberrations while reducing the size of the variable power optical system ZL. Set the upper limit of conditional expression (8) to 3.50, 3.00, 2.50, 2.00, 1.75, 1.50, 1.25, 1.15, and further to 1.00 , the effect of each embodiment can be made more reliable. Further, by setting the lower limit of conditional expression (8) to 0.20, 0.23, 0.25, 0.28, 0.30, 0.33, and further to 0.35, The effect can be made more reliable.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (9).
0.15<fRt/fF<5.00 (9)
where fRt is the focal length of the rear group GR in the telephoto end state

Conditional expression (9) defines an appropriate relationship between the focal length of the rear group GR and the focal length of the focusing group GF in the telephoto end state. By satisfying conditional expression (9), it is possible to satisfactorily correct various aberrations while maintaining a compact size.

If the corresponding value of conditional expression (9) exceeds the upper limit, it becomes difficult to correct various aberrations while reducing the size of the variable power optical system ZL. Set the upper limit of conditional expression (9) to 4.50, 4.00, 3.75, 3.50, 3.25, 3.00, 2.75, 2.50, and further to 2.30 and,
The effect of each embodiment can be made more reliable. Further, the lower limit of conditional expression (9) is set to 0.20, 0.25, 0.30, 0.33, 0.35, 0.38, 0.40, 0.43, 0.45, and further to 0 By setting it to 0.48, the effect of each embodiment can be made more reliable.

In the variable magnification optical system ZL according to the first and second embodiments, it is desirable that at least one lens group in the rear group GR is a plurality of lens groups. This makes it possible to satisfactorily correct the curvature of field.

In the variable-magnification optical system ZL according to the first and second embodiments, at least one lens group of the rear group GR is a second lens group having positive refractive power disposed closest to the object side of the rear group GR. It is desirable to include G2. This makes it possible to satisfactorily correct spherical aberration and coma.

In the variable-magnification optical system ZL according to the first and second embodiments, at least one lens group of the rear group GR is the final lens group GE having a positive refractive power disposed closest to the image side of the rear group GR. should be included. This makes it possible to satisfactorily correct the curvature of field.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (10).
0.10<fRPF/fRPR<0.60 (10)
where fRPF: the focal length of the lens group closest to the object side among the lens groups having positive refractive power among at least one lens group of the rear group GR; Focal length of the lens group closest to the image side in the lens group with refractive power

Conditional expression (10) defines the focal length of the lens group closest to the object side among the lens groups having positive refractive power among at least one lens group of the rear group GR, and , and the focal length of the lens group closest to the image side among the lens groups having positive refractive power. By satisfying the conditional expression (10), field curvature, spherical aberration, coma, and the like can be satisfactorily corrected while being compact.

When the corresponding value of conditional expression (10) exceeds the upper limit, the focal length of the lens group closest to the image side among the lens groups having positive refractive power in the rear group GR becomes short, so that field curvature can be corrected. become difficult. By setting the upper limit of conditional expression (10) to 0.55, 0.50, 0.48, 0.45, 0.43, and further to 0.40, the effect of each embodiment can be more assured. can be

When the corresponding value of conditional expression (10) is below the lower limit, the focal length of the lens group closest to the object side among the lens groups having positive refractive power in the rear group GR becomes short, so that spherical aberration and coma are corrected. becomes difficult. By setting the lower limit of conditional expression (10) to 0.13, 0.15, 0.18, and further to 0.20, the effect of each embodiment can be made more reliable.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (11).
0.05<Bfw/fRPR<0.35 (11)
where Bfw: back focus of the variable magnification optical system ZL in the wide-angle end state fRPR: the focal length of the lens group closest to the image side among the at least one lens group in the rear group GR and having positive refractive power

Conditional expression (11) defines the back focus of the variable power optical system ZL in the wide-angle end state, and the focal point of the lens group closest to the image side among at least one lens group in the rear group GR having positive refractive power. It defines an appropriate relationship with distance. By satisfying the conditional expression (11), it is possible to satisfactorily correct various aberrations such as curvature of field while maintaining a small size. In each embodiment, the back focus of the variable power optical system ZL is the distance on the optical axis from the lens surface closest to the image side of the variable power optical system ZL to the image plane I when focusing on infinity (air conversion distance ).

When the corresponding value of conditional expression (11) exceeds the upper limit, the focal length of the lens group closest to the image side among the lens groups having positive refractive power in the rear group GR becomes short, so that field curvature can be corrected. become difficult. By setting the upper limit of conditional expression (11) to 0.33, 0.30, 0.28, 0.25, and further to 0.23, the effect of each embodiment can be made more reliable. can.

When the corresponding value of conditional expression (11) is below the lower limit, the focal length of the lens group closest to the image side among the lens groups having positive refractive power in the rear group GR becomes too long, so that the curvature of field is sufficiently corrected. becomes difficult to do. By setting the lower limit of conditional expression (11) to 0.06, and further to 0.08, the effect of each embodiment can be made more reliable.

In the variable power optical system ZL according to the first and second embodiments, it is desirable that the lens disposed closest to the object side in the rear group GR is a positive lens. This makes it possible to satisfactorily correct the curvature of field.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably has a diaphragm arranged between the first lens group G1 and the rear group GR. As a result, coma aberration can be satisfactorily corrected.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (12).
60.00°<2ωw<90.00° (12)
where 2ωw: the total angle of view of the variable magnification optical system ZL in the wide-angle end state

Conditional expression (12) defines an appropriate range for the total angle of view of the variable power optical system ZL in the wide-angle end state. Satisfying the conditional expression (12) is preferable because it is possible to obtain a compact variable power optical system having good optical performance. By setting the upper limit of conditional expression (12) to 85.00°, 83.00°, 80.00°, and further 78.00°, the effect of each embodiment can be made more reliable. can. By setting the lower limit of conditional expression (12) to 63.00°, 65.00°, 68.00°, and further 70.00°, the effect of each embodiment can be made more reliable. can.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (13).
1.50<(-f1)/fRw<3.00 (13)
where f1: focal length of the first lens group G1 fRw: focal length of the rear group GR in the wide-angle end state

Conditional expression (13) defines an appropriate relationship between the focal length of the first lens group G1 and the focal length of the rear group GR in the wide-angle end state. Satisfying conditional expression (13) makes it possible to obtain good optical performance over the entire range of zooming while maintaining a small size.

If the corresponding value of conditional expression (13) exceeds the upper limit, it becomes difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (13) to 2.95, 2.90, 2.85, 2.80, 2.75, and further to 2.70, the effect of each embodiment is more reliable. can be

When the corresponding value of conditional expression (13) is below the lower limit, it becomes difficult to correct spherical aberration and curvature of field. Each implementation The shape effect can be made more reliable.

The variable power optical system ZL according to the first embodiment and the second embodiment preferably satisfies the following conditional expression (14).
0.50<(-f1)/fRt<2.50 (14)
where f1: focal length of the first lens group G1 fRt: focal length of the rear group GR in the telephoto end state

Conditional expression (14) defines an appropriate relationship between the focal length of the first lens group G1 and the focal length of the rear group GR in the telephoto end state. Satisfying conditional expression (14) makes it possible to obtain excellent optical performance over the entire range of zooming while maintaining a small size.

If the corresponding value of conditional expression (14) exceeds the upper limit, it becomes difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (14) to 2.40, 2.30, 2.20, 2.10, 2.05, and further to 2.00, the effect of each embodiment can be made more reliable. can be

When the corresponding value of conditional expression (14) is below the lower limit, it becomes difficult to correct spherical aberration and curvature of field. By setting the lower limit of conditional expression (14) to 0.55, 0.65, 0.75, 0.85, and further to 0.90, the effect of each embodiment can be made more reliable. can.

Next, a method for manufacturing the variable power optical system ZL according to the first embodiment will be outlined with reference to FIG. First, the first lens group G1 having negative refractive power and the rear group GR having at least one lens group are arranged in order from the object side along the optical axis (step ST1). Next, it is configured so that the distance between adjacent lens groups changes during zooming (step ST2). Next, in at least one lens group of the rear group GR, at least a portion of any lens group is a focusing group GF having positive refractive power that moves along the optical axis during focusing. (step ST3). Then, each lens is arranged in the lens barrel so as to satisfy at least the conditional expression (1) (step ST4). According to such a manufacturing method, it is possible to manufacture a variable-magnification optical system that is compact and yet has good optical performance.

Next, a method for manufacturing the variable magnification optical system ZL according to the second embodiment will be outlined. Since the manufacturing method of the variable power optical system ZL according to the second embodiment is the same as the manufacturing method described in the first embodiment, it will be described with reference to FIG. 12, which is the same as in the first embodiment. First, the first lens group G1 having negative refractive power and the rear group GR having at least one lens group are arranged in order from the object side along the optical axis (step ST1). Next, it is configured so that the distance between adjacent lens groups changes during zooming (step ST2). Next, in at least one lens group of the rear group GR, at least a portion of any lens group is a focusing group GF having positive refractive power that moves along the optical axis during focusing. (step ST3). Then, each lens is arranged in the lens barrel so as to satisfy at least the conditional expression (2) (step ST4). According to such a manufacturing method, it is possible to manufacture a variable-magnification optical system that is compact and yet has good optical performance.

A variable power optical system ZL according to an example of each embodiment will be described below with reference to the drawings. 1, 3, 5, 7, and 9 are cross-sections showing configurations and refractive power distributions of variable magnification optical systems ZL {ZL(1) to ZL(5)} according to first to fifth examples. It is a diagram. In the cross-sectional views of the variable power optical systems ZL(1) to ZL(5) according to the first to fifth embodiments, the direction of movement of the focusing group along the optical axis when focusing on a short distance object from infinity is shown as It is indicated by an arrow together with the word "focus". In the cross-sectional views of the variable power optical systems ZL(1) to ZL(5) according to the first to fifth examples, each lens group when changing power from the wide-angle end state (W) to the telephoto end state (T). Arrows indicate directions of movement along the optical axis.

1, 3, 5, 7 and 9, 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. 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 5 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. It is a table|surface which shows each specification data in 5 Example. 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, ω is the half angle of view (unit is degrees), and Y is the image height. TL indicates the distance obtained by adding Bf (back focus) to the distance on the optical axis from the lens surface closest to the object side to the lens surface closest to the image side of the variable-magnification optical system when focusing at infinity, where Bf is infinity. It shows the distance (air conversion distance) on the optical axis from the most image side lens surface of the variable power optical system to the image plane at the time of focusing. Note that these values are shown for each of the zooming states of the wide-angle end (W) and the telephoto end (T).

In the [Overall Specifications] table, fF indicates the focal length of the focusing group. fRw represents the focal length of the rear group in the wide-angle end state. fRt indicates the focal length of the rear group in the telephoto end state. fFRw indicates the focal length of a lens group (image-side lens group) composed of lenses arranged closer to the image side than the in-focus group in the wide-angle end state. fFRt indicates the focal length of a lens group (image-side lens group) composed of lenses arranged closer to the image side than the in-focus group in the telephoto end state. fRPF indicates the focal length of the lens group closest to the object side among the lens groups having positive refractive power among at least one lens group of the rear group. fRPR indicates the focal length of the lens group closest to the image side among the at least one lens group in the rear group and having positive refractive power. βRw indicates the lateral magnification of the rear group in the wide-angle end state. βRt indicates the lateral magnification of the rear group in the telephoto 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 for the d-line of the material of the optical member, and νd is the optical The Abbe numbers of the materials of the members are shown with reference to the d-line. The radius of curvature “∞” indicates a plane or an aperture, and (diaphragm S) indicates an aperture diaphragm S, respectively. The description of the refractive index of air nd=1.00000 is omitted. When the optical surface is an aspherical surface, the surface number is marked with *, 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 (sag 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 aspherical coefficient A2 is 0,
The description is omitted.

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

The [Variable Spacing Data] table shows the surface spacing for the surface number i whose surface spacing is (Di) in the [Lens Specifications] table. The [Variable Spacing Data] table shows the surface spacing in the infinity focused state and the surface spacing in the close distance focused state.

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

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 and 2 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 negative refractive power, an aperture stop S, and a positive refractive power, arranged in order from the object side along the optical axis. , a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. be. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are aligned with the optical axis. , and the distance between adjacent lens groups changes. During zooming, the aperture diaphragm S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 is fixed with respect to the image plane I. 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 is composed of a biconcave negative lens L11 and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The negative lens L11 has aspheric lens surfaces on both sides.

The second lens group G2 includes a positive meniscus lens L21 with a convex surface facing the object side, a biconvex positive lens L22, and a negative meniscus lens with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. and a lens L23. The positive meniscus lens L21 has aspheric lens surfaces on both sides.

The third lens group G3 is composed of a negative meniscus lens L31 having a concave surface facing the object side and a biconvex positive lens L32, which are arranged in order from the object side along the optical axis. The positive lens L32 has an aspheric lens surface on the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 having a concave surface facing the object side. The negative meniscus lens L41 has an aspheric lens 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. The positive meniscus lens L51 has an aspheric lens surface on the image side. An image plane I is arranged on the image side of the fifth lens group G5.

In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute a rear group GR having positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE arranged closest to the image side of the rear group GR. The entire third lens group G3 constitutes a focusing group GF that moves along the optical axis during focusing. During focusing from an infinity object to a close object, the focusing group GF (the entirety of the third lens group G3) moves along the optical axis toward the object side. The fourth lens group G4 (negative meniscus lens L41) and the fifth lens group G5 (positive meniscus lens L51) form an image-side lens group GFR consisting of lenses arranged closer to the image side than the focusing group GF. Configure.

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

(Table 1)
[Overall specifications]
Zoom ratio = 1.636
fF = 39.167
fRw = 22.595 fRt = 29.061
fFRw = -41.499 fFRt = -59.874
fRPF = 20.954 fRPR = 70.338
βRw=-0.617 βRt=-1.010
WMT
f 29.700 38.460 48.600
FNO 4.760 5.730 6.600
ω 36.800 30.000 23.900
Y 20.260 21.600 21.600
TL 53.000 54.360 55.000
Bf 9.350 9.350 9.350
[Lens specifications]
Surface number R D nd νd
1* -46.45344 0.70000 1.592450 66.92
2* 32.53983 0.27192
3 31.89076 1.16857 1.922860 20.88
4 49.15523 (D4)
5 ∞ 0.75000 (Aperture S)
6* 9.25078 1.69319 1.592550 67.86
7* 22.86502 0.52358
8* 21.08977 2.02472 1.497103 81.56
9 -33.77515 0.10000
10 14.66767 0.60000 1.805180 25.45
11 8.87343 (D11)
12 -10.72084 0.60000 1.647690 33.72
13 -88.96305 0.10000
14 153.50950 4.46285 1.806040 40.74
15* -12.62204 (D15)
16* -12.55590 1.10000 1.592550 67.86
17-124.66776 (D17)
18 -76.00140 4.00911 1.806040 40.74
19* -33.23634 Bf
[Aspheric data]
1st surface κ=1.0000, A4=-2.87832E-05, A6=5.37667E-07, A8=-1.89799E-09, A10=0.00000E+00
Second surface κ=1.0000, A4=-3.52496E-05, A6=4.89315E-07, A8=0.00000E+00, A10=0.00000E+00
6th surface κ=1.0000, A4=4.25254E-04, A6=6.57900E-06, A8=0.00000E+00, A10=0.00000E+00
7th surface κ=1.0000, A4=1.56672E-03, A6=-2.37553E-06, A8=0.00000E+00, A10=0.00000E+00
8th surface κ=1.0000, A4=1.07233E-03, A6=-1.74719E-05, A8=0.00000E+00, A10=0.00000E+00
15th surface κ=1.0000, A4=5.95097E-05, A6=2.02778E-07, A8=0.00000E+00, A10=0.00000E+00
16th surface κ=1.0000, A4=6.61988E-05, A6=3.19123E-08, A8=0.00000E+00, A10=0.00000E+00
19th surface κ=1.0000, A4=1.04032E-05, A6=-1.75552E-08, A8=0.00000E+00, A10=0.00000E+00
[Variable interval data]
Infinity focus
WMT
Focal length 29.700 38.460 48.600
Object distance ∞ ∞ ∞
D4 9.80415 5.69022 0.77539
D11 7.02876 8.50376 7.42174
D15 6.66505 4.79534 5.00000
D17 2.04808 7.91189 14.34901
close-range focus
WMT
Magnification -0.09457 -0.12295 -0.15908
Object distance 300.0000 300.0000 300.0000
D4 9.80415 5.69022 0.77539
D11 4.41909 5.26604 3.84392
D15 9.27473 8.03306 8.57782
D17 2.04808 7.91189 14.34901
[Lens group data]
Group Starting surface Focal length
G1 1 -48.133
G26 20.954
G3 12 39.167
G4 16 -23.649
G5 18 70.338

FIG. 2A is a diagram of various aberrations in the wide-angle end state of the variable magnification optical system according to the first embodiment when focusing on infinity. FIG. 2B is a diagram of various aberrations in the telephoto end state of the variable power optical system according to the first embodiment when focusing on infinity. In each aberration diagram, FNO indicates F number and Y indicates 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 coma aberration diagram shows the value of each image height. d indicates the d-line (wavelength λ=587.6 nm) and g indicates the 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 various aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG. FIG. 3 is a diagram showing the lens configuration of the variable magnification optical system according to the second embodiment. The variable power optical system ZL(2) according to the second embodiment includes a first lens group G1 having negative refractive power, an aperture stop S, and a positive refractive power, which are arranged in order from the object side along the optical axis. , a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. be. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are aligned with the optical axis. , and the distance between adjacent lens groups changes. During zooming, the aperture diaphragm S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 is fixed with respect to the image plane I.

The first lens group G1 is composed of a biconcave negative lens L11 and a biconvex positive lens L12, which are arranged in order from the object side along the optical axis. The negative lens L11 has aspheric lens surfaces on both sides.

The second lens group G2 is composed of a biconvex positive lens L21 and a negative meniscus lens L22 having a convex surface facing the object, which are arranged in order from the object side along the optical axis. The positive lens L21 has aspheric lens surfaces on both sides.

The third lens group G3 is composed of a negative meniscus lens L31 having a concave surface facing the object side and a biconvex positive lens L32, which are arranged in order from the object side along the optical axis. The positive lens L32 has an aspheric lens surface on the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 having a convex surface facing the object side and a negative meniscus lens L42 having a concave surface facing the object side, which are arranged in order from the object side along the optical axis. The negative meniscus lens L42 has an aspheric lens surface on the image side.

The fifth lens group G5 is composed of a positive meniscus lens L51 having a concave surface facing the object side. The positive meniscus lens L51 has an aspheric lens surface on the image side. An image plane I is arranged on the image side of the fifth lens group G5.

In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute a rear group GR having positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE arranged closest to the image side of the rear group GR. The entire third lens group G3 constitutes a focusing group GF that moves along the optical axis during focusing. During focusing from an infinity object to a close object, the focusing group GF (the entirety of the third lens group G3) moves along the optical axis toward the object side. Also, the fourth lens group G4 (negative meniscus lens L41 and negative meniscus lens L42) and the fifth lens group G5 (positive meniscus lens L51) are lenses arranged closer to the image side than the focusing group GF. This constitutes a side lens group GFR.

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

(Table 2)
[Overall specifications]
Zoom ratio = 1.636
fF = 26.338
fRw = 26.032 fRt = 58.204
fFRw = -29.697 fFRt = -53.723
fRPF = 21.696 fRPR = 55.306
βRw=-0.449 βRt=-0.601
WMT
f 29.700 38.000 48.600
FNO 4.760 5.730 6.600
ω 36.600 29.600 23.700
Y 20.800 21.600 21.600
TL 49.450 41.640 54.950
Bf 9.400 9.410 9.400
[Lens specifications]
Surface number R D nd νd
1* -30.00033 0.70000 1.677980 54.89
2* 27.02686 0.30000
3 44.93551 1.30000 2.001000 29.12
4-169.34876 (D4)
5 ∞ 0.75000 (Aperture S)
6* 8.93744 2.40000 1.497103 81.56
7* -41.28092 0.10000
8 9.85432 0.85000 1.846660 23.80
9 7.22445 (D9)
10 -9.42267 0.60000 1.592700 35.27
11 -36.11138 0.53556
12 44.47304 3.77778 1.658440 50.83
13* -10.73978 (D13)
14 83.46657 0.60000 1.677980 54.89
15 19.47713 7.71820
16 -9.23773 1.10000 1.592550 67.86
17* -18.61767 (D17)
18 -48.35114 4.85915 1.820980 42.50
19* -24.47680 Bf
[Aspheric data]
1st surface κ=1.0000, A4=7.08353E-07, A6=-7.32782E-08, A8=1.68078E-10, A10=0.00000E+00
Second surface κ=1.0000, A4=-2.56974E-05, A6=-1.03240E-07, A8=0.00000E+00, A10=0.00000E+00
6th surface κ=1.0000, A4=-1.17527E-04, A6=-1.07846E-06, A8=0.00000E+00, A10=0.00000E+00
7th surface κ=1.0000, A4=4.05573E-05, A6=-1.34572E-08, A8=0.00000E+00, A10=0.00000E+00
13th surface κ=1.0000, A4=1.20435E-04, A6=5.06907E-07, A8=0.00000E+00, A10=0.00000E+00
17th surface κ=1.0000, A4=-4.34454E-05, A6=-1.59225E-07, A8=0.00000E+00, A10=0.00000E+00
19th surface κ=1.0000, A4=3.48547E-06, A6=1.98136E-08, A8=0.00000E+00, A10=0.00000E+00
[Variable interval data]
Infinity focus
WMT
Focal length 29.700 38.000 48.600
Object distance ∞ ∞ ∞
D4 7.79982 3.90180 0.75000
D9 3.42610 3.93525 4.42251
D13 2.53363 1.66766 0.90000
D17 0.70000 6.54202 13.88678
close-range focus
WMT
Magnification -0.09863 -0.12512 -0.16148
Object distance 300.0000 300.0000 300.0000
D4 7.79982 3.90180 0.75000
D9 2.26584 2.56819 2.84604
D13 3.69388 3.03472 2.47647
D17 0.70000 6.54202 13.88678
[Lens group data]
Group Starting surface Focal length
G1 1 -52.725
G2 6 21.696
G3 10 26.338
G4 14 -15.833
G5 18 55.306

FIG. 4A is a diagram of various aberrations in the wide-angle end state of the variable power optical system according to the second embodiment when focusing on infinity. FIG. 4B is a diagram of various aberrations in the telephoto end state of the variable power optical system according to the second embodiment when focusing on infinity. From the various aberration diagrams, it can be seen that the variable power optical system according to the second example has various aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

(Third embodiment)
A third embodiment will be described with reference to FIGS. 5 to 6 and Table 3. FIG. FIG. 5 is a diagram showing the lens configuration of the variable magnification optical system according to the third embodiment. The variable magnification optical system ZL(3) according to the third embodiment includes a first lens group G1 having negative refractive power, an aperture diaphragm S, and a positive refractive power, which are arranged in order from the object side along the optical axis. , a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. be. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are aligned with the optical axis. , and the distance between adjacent lens groups changes. During zooming, the aperture diaphragm S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 is fixed with respect to the image plane I.

The first lens group G1 is composed of a biconcave negative lens L11 and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The negative lens L11 has aspheric lens surfaces on both sides.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a positive meniscus lens L22 having a convex surface facing the object side, and a convex surface facing the object side, which are arranged in order from the object side along the optical axis. and a negative meniscus lens L23. Positive meniscus lens L21
has aspherical lens surfaces on both sides.

The third lens group G3 is composed of a negative meniscus lens L31 having a concave surface facing the object side and a biconvex positive lens L32, which are arranged in order from the object side along the optical axis. The positive lens L32 has an aspheric lens surface on the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 having a concave surface facing the object side. The negative meniscus lens L41 has an aspheric lens surface on the image side.

The fifth lens group G5 is composed of a positive meniscus lens L51 having a concave surface facing the object side. The positive meniscus lens L51 has an aspheric lens surface on the image side. An image plane I is arranged on the image side of the fifth lens group G5.

In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute a rear group GR having positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE arranged closest to the image side of the rear group GR. The entire third lens group G3 constitutes a focusing group GF that moves along the optical axis during focusing. During focusing from an infinity object to a close object, the focusing group GF (the entirety of the third lens group G3) moves along the optical axis toward the object side. The fourth lens group G4 (negative meniscus lens L41) and the fifth lens group G5 (positive meniscus lens L51) form an image-side lens group GFR consisting of lenses arranged closer to the image side than the focusing group GF. Configure.

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 = 1.636
fF = 42.997
fRw = 28.117 fRt = 47.910
fFRw = -53.580 fFRt = -76.170
fRPF = 23.675 fRPR = 80.136
βRw=-0.471 βRt=-0.612
WMT
f 29.700 38.000 48.600
FNO 4.620 5.500 6.630
ω 36.950 30.400 23.770
Y 20.030 21.600 21.600
TL 53.000 53.500 56.560
Bf 9.350 9.350 9.350
[Lens specifications]
Surface number R D nd νd
1* -31.73727 0.70000 1.497103 81.56
2* 29.09010 0.44719
3 43.66364 1.20961 2.000690 25.46
4 122.92529 (D4)
5 ∞ 0.75000 (Aperture S)
6* 12.35536 1.63881 1.497103 81.56
7* 57.04352 0.10000
8 12.73259 1.70614 1.496997 81.61
9 197.72930 0.10000
10 13.90270 0.60000 1.784720 25.64
11 8.83064 (D11)
12 -12.80974 0.55000 1.749500 35.25
13 -617.21941 0.10000
14 71.30483 5.01710 1.820980 42.50
15* -13.72803 (D15)
16 -13.40787 1.10000 1.563840 60.71
17* -68.71419 (D17)
18 -45.00000 3.23796 1.902650 35.77
19* -28.68872 Bf
[Aspheric data]
1st surface κ=1.0000, A4=6.95146E-06, A6=7.90721E-08, A8=-4.86954E-10, A10=0.00000E+00
Second surface κ=1.0000, A4=-1.21033E-05, A6=4.19563E-08, A8=0.00000E+00, A10=0.00000E+00
6th surface κ=1.0000, A4=-3.26113E-05, A6=5.99810E-07, A8=0.00000E+00, A10=0.00000E+00
7th surface κ=1.0000, A4=4.51406E-05, A6=7.80522E-07, A8=0.00000E+00, A10=0.00000E+00
15th surface κ=1.0000, A4=5.20915E-05, A6=1.39991E-07, A8=0.00000E+00, A10=0.00000E+00
17th surface κ=1.0000, A4=-3.68987E-05, A6=7.05431E-08, A8=0.00000E+00, A10=0.00000E+00
19th surface κ=1.0000, A4=2.55064E-06, A6=1.13229E-08, A8=0.00000E+00, A10=0.00000E+00
[Variable interval data]
Infinity focus
WMT
Focal length 29.700 38.000 48.600
Object distance ∞ ∞ ∞
D4 8.70643 4.12083 0.50000
D11 6.88074 8.48181 10.47382
D15 10.10609 7.59408 5.07986
D17 0.70000 6.69783 13.89998
close-range focus
WMT
Magnification -0.09550 -0.12308 -0.15793
Object distance 300.0000 300.0000 300.0000
D4 8.70643 4.12083 0.50000
D11 3.91794 4.80666 5.95890
D15 13.06889 11.26923 9.59478
D17 0.70000 6.69783 13.89998
[Lens group data]
Group Starting surface Focal length
G1 1 -56.116
G2 6 23.675
G3 12 42.997
G4 16 -29.758
G5 18 80.136

FIG. 6A is a diagram of various aberrations in the wide-angle end state of the variable power optical system according to the third embodiment when focusing on infinity. FIG. 6B is a diagram of various aberrations in the telephoto end state of the variable power optical system according to the third embodiment when focusing at infinity. From the various aberration diagrams, it can be seen that the variable magnification optical system according to the third example has various aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

(Fourth embodiment)
A fourth embodiment will be described with reference to FIGS. 7 to 8 and Table 4. FIG. FIG. 7 is a diagram showing the lens configuration of a variable-magnification optical system according to the fourth embodiment. The variable magnification optical system ZL(4) according to the fourth embodiment includes a first lens group G1 having negative refractive power, an aperture diaphragm S, and a positive refractive power, which are arranged in order from the object side along the optical axis. , a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. be. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are aligned with the optical axis. , and the distance between adjacent lens groups changes. During zooming, the aperture diaphragm S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 is fixed with respect to the image plane I.

The first lens group G1 is composed of a biconcave negative lens L11 and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The negative lens L11 has aspheric lens surfaces on both sides.

The second lens group G2 includes a positive meniscus lens L21 with a convex surface facing the object side, a biconvex positive lens L22, and a negative meniscus lens with a convex surface facing the object side, which are arranged in order from the object side along the optical axis. and a lens L23. The positive meniscus lens L21 has aspheric lens surfaces on both sides. The positive lens L22 has an aspheric lens surface on the object side.

The third lens group G3 is composed of a negative meniscus lens L31 having a concave surface facing the object side and a positive meniscus lens L32 having a concave surface facing the object side, which are arranged in order from the object side along the optical axis. The positive meniscus lens L32 has an aspheric lens surface on the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 having a concave surface facing the object side. The negative meniscus lens L41 has an aspheric lens 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. The positive meniscus lens L51 has an aspheric lens surface on the image side. An image plane I is arranged on the image side of the fifth lens group G5.

In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute a rear group GR having positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE arranged closest to the image side of the rear group GR. The entire third lens group G3 constitutes a focusing group GF that moves along the optical axis during focusing. During focusing from an infinity object to a short distance object, the focusing group GF (the entirety of the third lens group G3) moves along the optical axis toward the object side. The fourth lens group G4 (negative meniscus lens L41) and the fifth lens group G5 (positive meniscus lens L51) form an image-side lens group GFR consisting of lenses arranged closer to the image side than the focusing group GF. Configure.

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

(Table 4)
[Overall specifications]
Zoom ratio = 1.636
fF = 39.607
fRw = 14.368 fRt = 19.725
fFRw = -38.346 fFRt = -47.636
fRPF = 19.063 fRPR = 92.773
βRw=-0.520 βRt=-0.827
WMT
f 29.700 38.100 48.600
FNO 4.860 5.710 6.670
ω 36.990 30.866 24.530
Y 19.910 21.600 21.600
TL 53.000 53.500 56.560
Bf 9.350 9.350 9.350
[Lens specifications]
Surface number R D nd νd
1* -30.22701 0.70000 1.592450 66.92
2* 36.12436 0.25453
3 30.95344 1.15584 1.922860 20.88
4 46.70993 (D4)
5 ∞ 0.75000 (Aperture S)
6* 9.39854 2.20000 1.592550 67.86
7* 27.34671 0.51079
8* 25.75786 2.17114 1.497103 81.56
9 -22.85474 0.10000
10 18.36723 0.60000 1.805180 25.45
11 10.11386 (D11)
12 -10.75318 0.55000 1.647690 33.72
13 -29.87660 0.90072
14 -112.83117 3.80151 1.806040 40.74
15* -13.08031 (D15)
16* -13.03175 1.10000 1.592550 67.86
17-123.29153 (D17)
18 -47.94418 3.31541 1.806040 40.74
19* -30.11543 Bf
[Aspheric data]
1st surface κ=1.0000, A4=2.22481E-05, A6=1.01445E-07, A8=-4.79173E-10, A10=0.00000E+00
Second surface κ=1.0000, A4=1.60025E-05, A6=1.58116E-07, A8=0.00000E+00, A10=0.00000E+00
6th surface κ=1.0000, A4=3.49725E-04, A6=3.83667E-06, A8=0.00000E+00, A10=0.00000E+00
7th surface κ=1.0000, A4=1.47564E-03, A6=-3.55272E-06, A8=0.00000E+00, A10=0.00000E+00
8th surface κ=1.0000, A4=9.92751E-04, A6=-1.52345E-05, A8=0.00000E+00, A10=0.00000E+00
15th surface κ=1.0000, A4=4.70062E-05, A6=1.55390E-07, A8=0.00000E+00, A10=0.00000E+00
16th surface κ=1.0000, A4=6.63363E-05, A6=4.07593E-08, A8=0.00000E+00, A10=0.00000E+00
19th surface κ=1.0000, A4=1.37067E-05, A6=-3.22794E-08, A8=0.00000E+00, A10=0.00000E+00
[Variable interval data]
Infinity focus
WMT
Focal length 29.700 38.100 48.600
Object distance ∞ ∞ ∞
D4 8.46288 4.50520 0.78230
D11 6.58757 6.69428 7.03152
D15 6.16194 5.33365 5.04300
D17 3.03775 8.84685 14.68335
close-range focus
WMT
Magnification -0.09468 -0.12283 -0.15875
Object distance 300.0000 300.0000 300.0000
D4 8.46288 4.50520 0.78230
D11 3.98574 3.68930 3.48054
D15 8.76377 8.33863 8.59397
D17 3.03775 8.84685 14.68335
[Lens group data]
Group Starting surface Focal length
G1 1 -38.500
G2 6 19.063
G3 12 39.607
G4 16 -24.684
G5 18 92.773

FIG. 8A is a diagram of various aberrations in the wide-angle end state of the variable power optical system according to the fourth embodiment when focusing on infinity. FIG. 8B is a diagram of various aberrations in the telephoto end state of the variable power optical system according to the fourth example when focusing on infinity. From the various aberration diagrams, it can be seen that the variable magnification optical system according to the fourth example has various aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

(Fifth embodiment)
A fifth embodiment will be described with reference to FIGS. 9 to 10 and Table 5. FIG. FIG. 9 is a diagram showing the lens configuration of the variable power optical system according to the fifth embodiment. The variable magnification optical system ZL(5) according to the fifth embodiment includes a first lens group G1 having negative refractive power, an aperture diaphragm S, and a positive refractive power, which are arranged in order from the object side along the optical axis. , a third lens group G3 having positive refractive power, a fourth lens group G4 having negative refractive power, and a fifth lens group G5 having positive refractive power. be. When zooming from the wide-angle end state (W) to the telephoto end state (T), the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are aligned with the optical axis. , and the distance between adjacent lens groups changes. During zooming, the aperture diaphragm S moves along the optical axis together with the second lens group G2, and the position of the fifth lens group G5 is fixed with respect to the image plane I.

The first lens group G1 is composed of a biconcave negative lens L11 and a positive meniscus lens L12 having a convex surface facing the object side, which are arranged in order from the object side along the optical axis. The negative lens L11 has aspheric lens surfaces on both sides.

The second lens group G2 includes biconvex positive lenses L21 arranged in order from the object side along the optical axis.
and a negative meniscus lens L22 having a convex surface facing the object side. The positive lens L21 has aspheric lens surfaces on both sides.

The third lens group G3 is composed of a negative meniscus lens L31 having a concave surface facing the object side and a biconvex positive lens L32, which are arranged in order from the object side along the optical axis. The positive lens L32 has an aspheric lens surface on the image side.

The fourth lens group G4 is composed of a negative meniscus lens L41 having a convex surface facing the object side and a negative meniscus lens L42 having a concave surface facing the object side, which are arranged in order from the object side along the optical axis. The negative meniscus lens L42 has an aspheric lens surface on the image side.

The fifth lens group G5 is composed of a positive meniscus lens L51 having a concave surface facing the object side. The positive meniscus lens L51 has an aspheric lens surface on the image side. An image plane I is arranged on the image side of the fifth lens group G5.

In this embodiment, the second lens group G2, the third lens group G3, the fourth lens group G4, and the fifth lens group G5 constitute a rear group GR having positive refractive power as a whole. The fifth lens group G5 corresponds to the final lens group GE arranged closest to the image side of the rear group GR. The entire third lens group G3 constitutes a focusing group GF that moves along the optical axis during focusing. During focusing from an infinity object to a close object, the focusing group GF (the entirety of the third lens group G3) moves along the optical axis toward the object side. Also, the fourth lens group G4 (negative meniscus lens L41 and negative meniscus lens L42) and the fifth lens group G5 (positive meniscus lens L51) are lenses arranged closer to the image side than the focusing group GF. This constitutes a side lens group GFR.

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 = 1.636
fF = 31.496
fRw = 18.762 fRt = 37.924
fFRw = -36.619 fFRt = -56.429
fRPF = 23.697 fRPR = 68.376
βRw=-0.461 βRt=-0.831
WMT
f 29.700 38.000 48.600
FNO 4.580 5.430 6.500
ω 37.080 30.530 24.080
Y 20.040 21.600 21.600
TL 54.950 55.910 59.420
Bf 9.400 9.400 9.400
[Lens specifications]
Surface number R D nd νd
1* -42.08161 0.70000 1.592550 67.86
2* 19.04481 0.7948
3 24.04182 1.50000 1.850260 32.35
4 76.98855 (D4)
5 ∞ 0.75000 (Aperture S)
6* 10.14764 2.30492 1.497103 81.56
7* -41.88647 0.10000
8 10.76220 0.85000 1.846660 23.80
9 8.06657 (D9)
10 -9.84224 0.60000 1.647690 33.72
11 -30.44625 1.18506
12 302.30818 3.12363 1.773870 47.25
13* -12.17516 (D13)
14 69.03850 1.05590 1.667550 41.87
15 23.59872 10.14456
16 -13.80249 1.10000 1.603000 65.44
17* -33.16908 (D17)
18 -500.00000 4.50318 1.804400 39.61
19* -49.74990 Bf
[Aspheric data]
1st surface κ=1.0000, A4=-4.37082E-07, A6=1.20726E-08, A8=-7.58568E-11, A10=0.00000E+00
Second surface κ=1.0000, A4=-1.47336E-05, A6=-1.76298E-08, A8=0.00000E+00, A10=0.00000E+00
6th surface κ=1.0000, A4=-7.82571E-05, A6=-4.39086E-07, A8=0.00000E+00, A10=0.00000E+00
7th surface κ=1.0000, A4=2.97493E-05, A6=-3.34092E-08, A8=0.00000E+00, A10=0.00000E+00
13th surface κ=1.0000, A4=6.63179E-05, A6=2.88117E-07, A8=0.00000E+00, A10=0.00000E+00
17th surface κ=1.0000, A4=-2.73274E-05, A6=1.19063E-08, A8=0.00000E+00, A10=0.00000E+00
19th surface κ=1.0000, A4=2.70508E-06, A6=-2.22490E-09, A8=0.00000E+00, A10=0.00000E+00
[Variable interval data]
Infinity focus
WMT
Focal length 29.700 38.000 48.600
Object distance ∞ ∞ ∞
D4 9.13726 4.49172 0.75000
D9 4.33920 4.81383 5.20970
D13 2.65195 1.72334 0.90000
D17 0.70000 6.76704 14.44365
close-range focus
WMT
Magnification -0.09640 -0.12487 -0.16166
Object distance 300.0000 300.0000 300.0000
D4 9.13726 4.49172 0.75000
D9 2.82451 3.00662 3.08197
D13 4.14864 3.53055 3.02772
D17 0.70000 6.76704 14.44365
[Lens group data]
Group Starting surface Focal length
G1 1 -49.718
G2 6 23.697
G3 10 31.496
G4 14 -20.966
G5 18 68.376

FIG. 10A is a diagram of various aberrations in the wide-angle end state of the variable power optical system according to the fifth embodiment when focusing on infinity. FIG. 10B is a diagram of various aberrations in the telephoto end state of the variable magnification optical system according to the fifth embodiment when focusing at infinity. From the various aberration diagrams, it can be seen that the variable power optical system according to the fifth example has various aberrations well corrected from the wide-angle end state to the telephoto end state, and has excellent imaging performance.

Next, a table of [value corresponding to conditional expression] is shown below. This table collectively shows the values corresponding to each conditional expression (1) to (14) for all examples (first to fifth examples).
Conditional expression (1) 0.50<ft/fF<10.00
Conditional expression (2) 0.30<fw/fF<7.00
Conditional expression (3) 1.30<f2/(-X2)<2.50
Conditional expression (4) 1.00<βRt/βRw<2.25
Conditional expression (5) 0.30<(-fFRw)/fF<7.00
Conditional expression (6) 0.30<(-fFRt)/fF<7.00
Conditional expression (7) 0.20<fRPF/fF<3.00
Conditional expression (8) 0.15<fRw/fF<4.00
Conditional expression (9) 0.15<fRt/fF<5.00
Conditional expression (10) 0.10<fRPF/fRPR<0.60
Conditional expression (11) 0.05<Bfw/fRPR<0.35
Conditional expression (12) 60.00°<2ωw<90.00°
Conditional expression (13) 1.50<(-f1)/fRw<3.00
Conditional expression (14) 0.50<(-f1)/fRt<2.50

[Conditional Expression Corresponding Value] (First to Third Examples)
Conditional expression 1st embodiment 2nd embodiment 3rd embodiment (1) 1.241 1.845 1.130
(2) 0.758 1.128 0.691
(3) 1.900 1.729 2.012
(4) 1.636 1.338 1.300
(5) 1.060 1.128 1.246
(6) 1.529 2.040 1.772
(7) 0.535 0.824 0.551
(8) 0.577 0.988 0.654
(9) 0.742 2.210 1.114
(10) 0.298 0.392 0.295
(11) 0.133 0.170 0.117
(12) 73.635 73.209 73.904
(13) 2.130 2.025 1.996
(14) 1.656 0.906 1.171
[Conditional Expression Corresponding Value] (Fourth and Fifth Examples)
Conditional expression 4th embodiment 5th embodiment (1) 1.227 1.543
(2) 0.750 0.943
(3) 1.738 1.842
(4) 1.592 1.802
(5) 0.968 1.163
(6) 1.203 1.792
(7) 0.481 0.752
(8) 0.363 0.596
(9) 0.498 1.204
(10) 0.205 0.347
(11) 0.101 0.138
(12) 73.971 74.162
(13) 2.680 2.650
(14) 1.952 1.311

According to each of the above embodiments, it is possible to realize a variable power optical system that is compact and has good optical performance.

Each of the above embodiments shows one specific example of the present invention, and the present invention 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-magnification optical system of this embodiment.

As an example of the variable-magnification optical system of the present embodiment, a five-group configuration is shown, but the present application is not limited to this, and a variable-magnification optical system having other group configurations (for example, six groups, seven groups, etc.) may be configured. You can also Specifically, a configuration in which a lens or lens group is added to the most object side or most image plane side of the variable power optical system of the present embodiment 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.

A single lens group, a plurality of lens groups, or a partial lens group may be moved along the optical axis to serve as a focusing lens group for focusing from an object at infinity to an object at a short distance. The focusing lens group can also be applied to autofocus, and is also suitable for motor drive (using an ultrasonic motor or the like) for autofocus.

Image blurring caused by camera shake is corrected by moving the lens group or partial lens group so that it has a component in the direction perpendicular to the optical axis, or rotating (oscillating) in the plane including the optical axis. It may be used as an anti-vibration lens group.

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 with 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 first lens group and the second 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.

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

Claims (22)

Consisting of a first lens group having a negative refractive power and a rear group having at least one lens group arranged in order from the object side along the optical axis,
When zooming, the distance between adjacent lens groups changes,
at least a portion of any lens group in the at least one lens group of the rear group is a focusing group having a positive refractive power that moves along an optical axis during focusing;
A variable magnification optical system that satisfies the following conditional expressions.
0.50<ft/fF<10.00
where ft is the focal length of the variable magnification optical system in the telephoto end state fF is the focal length of the focusing group Consisting of a first lens group having a negative refractive power and a rear group having at least one lens group arranged in order from the object side along the optical axis,
When zooming, the distance between adjacent lens groups changes,
at least a portion of any lens group in the at least one lens group of the rear group is a focusing group having a positive refractive power that moves along an optical axis during focusing;
A variable magnification optical system that satisfies the following conditional expressions.
0.30<fw/fF<7.00
where fw is the focal length of the variable magnification optical system in the wide-angle end state, fF is the focal length of the focusing group the at least one lens group of the rear group includes a second lens group having a positive refractive power disposed closest to the object side of the rear group;
3. A variable-magnification optical system according to claim 1, which satisfies the following conditional expression.
1.30<f2/(-X2)<2.50
where f2 is the focal length of the second lens group X2 is the amount of movement of the second lens group during zooming from the wide-angle end state to the telephoto end state (the amount of movement toward the image side is a positive value) 4. A variable-magnification optical system according to claim 1, which satisfies the following conditional expressions.
1.00<βRt/βRw<2.25
where βRt: lateral magnification of the rear group in the telephoto end state βRw: lateral magnification of the rear group in the wide-angle end state 5. A variable-magnification optical system according to claim 1, which satisfies the following conditional expressions.
0.30<(-fFRw)/fF<7.00
where fFRw is the focal length of a lens group composed of lenses arranged closer to the image side than the focusing group in the wide-angle end state 6. A variable-magnification optical system according to claim 1, which satisfies the following conditional expressions.
0.30<(-fFRt)/fF<7.00
where fFRt is the focal length of a lens group composed of lenses arranged closer to the image side than the focusing group in the telephoto end state 7. The variable power optical system according to claim 1, which satisfies the following conditional expressions.
0.20<fRPF/fF<3.00
However, fRPF: the focal length of the lens group closest to the object side among the at least one lens group of the rear group and having positive refractive power 8. A variable magnification optical system according to claim 1, which satisfies the following conditional expressions.
0.15<fRw/fF<4.00
where fRw is the focal length of the rear group in the wide-angle end state 9. A variable-magnification optical system according to claim 1, which satisfies the following conditional expressions.
0.15<fRt/fF<5.00
where fRt is the focal length of the rear group in the telephoto end state The variable power optical system according to any one of claims 1 to 9, wherein said at least one lens group in said rear group comprises a plurality of lens groups. 11. The zooming according to any one of claims 1 to 10, wherein the at least one lens group of the rear group includes a second lens group having positive refractive power disposed closest to the object side of the rear group. Optical system. The variable magnification optical system according to any one of claims 1 to 11, wherein said at least one lens group of said rear group includes a final lens group having positive refractive power disposed closest to the image side of said rear group. system. 13. The variable magnification optical system according to claim 1, which satisfies the following conditional expressions.
0.10<fRPF/fRPR<0.60
However, fRPF: Of the at least one lens group of the rear group, the focal length of the lens group closest to the object side among the lens groups having positive refractive power fRPR: Of the at least one lens group of the rear group, The focal length of the lens group closest to the image side in the lens group with positive refractive power 14. The variable magnification optical system according to any one of claims 1 to 13, which satisfies the following conditional expressions.
0.05<Bfw/fRPR<0.35
where Bfw: the back focus of the variable power optical system in the wide-angle end state fRPR: the focal length of the lens group closest to the image side among the at least one lens group of the rear group and having positive refractive power The variable power optical system according to any one of claims 1 to 14, wherein the lens in the rear group that is closest to the object side is a positive lens. 16. The variable power optical system according to any one of claims 1 to 15, further comprising a diaphragm disposed between said first lens group and said rear group. 17. The variable magnification optical system according to claim 1, which satisfies the following conditional expressions.
60.00°<2ωw<90.00°
where 2ωw: the total angle of view of the variable-magnification optical system in the wide-angle end state 18. The variable magnification optical system according to claim 1, which satisfies the following conditional expressions.
1.50<(-f1)/fRw<3.00
where f1: focal length of the first lens group fRw: focal length of the rear group in the wide-angle end state 19. The variable magnification optical system according to any one of claims 1 to 18, which satisfies the following conditional expressions.
0.50<(-f1)/fRt<2.50
where f1: focal length of the first lens group fRt: focal length of the rear group in the telephoto end state An optical instrument comprising the variable magnification optical system according to any one of claims 1 to 19. A method for manufacturing a variable power optical system comprising a first lens group having negative refractive power and a rear group having at least one lens group arranged in order from the object side along an optical axis, the method comprising:
When zooming, the distance between adjacent lens groups changes,
at least a portion of any lens group in the at least one lens group of the rear group is a focusing group having a positive refractive power that moves along an optical axis during focusing;
In order to satisfy the following conditional expression,
A method of manufacturing a variable-magnification optical system in which each lens is arranged in a lens barrel.
0.50<ft/fF<10.00
where ft is the focal length of the variable magnification optical system in the telephoto end state fF is the focal length of the focusing group A method for manufacturing a variable power optical system comprising a first lens group having negative refractive power and a rear group having at least one lens group arranged in order from the object side along an optical axis, the method comprising:
When zooming, the distance between adjacent lens groups changes,
at least a portion of any lens group in the at least one lens group of the rear group is a focusing group having a positive refractive power that moves along an optical axis during focusing;
In order to satisfy the following conditional expression,
A method of manufacturing a variable-magnification optical system in which each lens is arranged in a lens barrel.
0.30<fw/fF<7.00
where fw is the focal length of the variable magnification optical system in the wide-angle end state, fF is the focal length of the focusing group

Images