WO2020012639A1

WO2020012639A1 - Variable power optical system, optical apparatus, and production method for variable power optical system

Info

Publication number: WO2020012639A1
Application number: PCT/JP2018/026487
Authority: WO
Inventors: 陽子小松原; 武梅田
Original assignee: 株式会社ニコン
Priority date: 2018-07-13
Filing date: 2018-07-13
Publication date: 2020-01-16
Also published as: JP7103417B2; JPWO2020012639A1

Abstract

Provided is a variable power optical system that is compact, has favorable optical performance, and favorably suppresses image shake. The variable power optical system has, in order from an object side, a first lens group that has negative refractive power, a second lens group that has positive refractive power, a third lens group that has negative refractive power, and a fourth lens group that has positive refractive power. During changes in magnification, 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 distance between the third lens group and the fourth lens group changes. The second lens group comprises, in order from the object side, a 2a lens group that has positive refractive power, a 2b lens group that has positive refractive power, and a 2c lens group that has negative refractive power. Image shake is corrected as a result of the 2b lens group being moved such that a component for a direction that is orthogonal to the optical axis is included. During focusing, the third lens group moves in the optical axis direction.

Description

Magnification optical system, optical apparatus, and method of manufacturing magnification optical system

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

Conventionally, miniaturization and improvement of optical performance have been attempted in a variable power optical system used for an interchangeable lens camera or the like (for example, see Patent Document 1). However, there is a demand for better miniaturization and improvement in optical performance, as well as good image blurring.

Patent No. 5781244

The present invention
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power Group 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 fourth lens group change. The distance from the lens group changes,
The second lens group includes, in order from the object side, a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power,
The image blur is corrected by moving the second lens group so as to include a component in a direction perpendicular to the optical axis,
In focusing, the third lens group is a variable power optical system that moves in the optical axis direction.

Also, the present invention
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power A method of manufacturing a variable power optical system having
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 fourth lens group change. The distance between the lens group is configured to change,
The second lens group includes, in order from the object side, a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power. Configured to
Moving the 2b lens group so as to include a component in a direction perpendicular to the optical axis to correct image blur;
This is a method for manufacturing a variable power optical system configured to move the third lens group in the optical axis direction during focusing.

FIG. 1 is a cross-sectional view of the zoom optical system according to Example 1 in a wide-angle end state. 2A and 2B are graphs showing various aberrations of the variable power optical system according to Example 1 in the wide-angle end state and the telephoto end state, respectively. FIG. 3 is a cross-sectional view of the zoom optical system according to Example 2 in a wide-angle end state. 4A and 4B are graphs showing various aberrations of the variable power optical system according to Example 2 in the wide-angle end state and the telephoto end state, respectively. FIG. 5 is a cross-sectional view of the zoom optical system according to Example 3 at the wide-angle end. 6A and 6B are aberration diagrams of the variable power optical system according to Example 3 in the wide-angle end state and the telephoto end state, respectively. FIG. 7 is a cross-sectional view of the zoom optical system according to Example 4 in a wide-angle end state. 8A and 8B are graphs showing various aberrations of the variable power optical system according to Example 4 in the wide-angle end state and the telephoto end state, respectively. FIG. 9 is a sectional view of a variable power optical system according to Example 5 in a wide-angle end state. 10A and 10B are graphs showing various aberrations of the variable power optical system according to Example 5 in the wide-angle end state and the telephoto end state, respectively. FIG. 11 is a sectional view of a variable power optical system according to Example 6 at the wide-angle end. 12A and 12B are graphs showing various aberrations of the variable power optical system according to Example 6 in the wide-angle end state and the telephoto end state, respectively. FIG. 13 is a cross-sectional view of the zoom optical system according to Example 7 at the wide-angle end. 14A and 14B are graphs showing various aberrations of the variable power optical system according to Example 7 in the wide-angle end state and the telephoto end state, respectively. FIG. 15 is a cross-sectional view of the zoom optical system according to Example 8 in the wide-angle end state. 16A and 16B are graphs showing various aberrations of the variable power optical system according to Example 8 in the wide-angle end state and the telephoto end state, respectively. FIG. 17 is a diagram illustrating a configuration of a camera including a variable power optical system. FIG. 18 is a flowchart showing an outline of a method of manufacturing a variable power optical system.

Hereinafter, a method of manufacturing a variable power optical system, an optical device, and a variable power optical system according to an embodiment of the present invention will be described.
The variable power optical system according to the present embodiment includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power. , A fourth lens group having a positive refractive power, and at the time of zooming, the distance between the first lens group and the second lens group changes, and the second lens group and the third lens group And the distance between the third lens group and the fourth lens group changes. The second lens group includes, in order from the object side, a 2a lens group having a positive refractive power, A second b lens group having a negative refractive power and a second c lens group having a negative refractive power.

変 The variable power optical system of the present embodiment realizes variable power by such a configuration, can correct various aberrations favorably, and can realize miniaturization.

Also, with such a configuration, the variable power optical system of the present embodiment corrects image blur by moving the 2b lens group so as to include a component in a direction orthogonal to the optical axis. As a result, image blur due to camera shake can be minimized. In addition, the influence on the peripheral image plane such as the eccentric coma generated when correcting the image blur is reduced by the second a lens group disposed on the front side of the second lens group and the second c lens disposed on the rear side of the second lens group. Good correction can be made in groups.

In addition, with such a configuration, in the variable power optical system of the present embodiment, the third lens group moves in the optical axis direction during focusing. This makes it possible to reduce the size of the drive mechanism of the third lens group, which is the focusing lens group, and to obtain good optical performance from an in-focus object state to a short-distance object focus state.

With the above configuration, the variable power optical system of the present embodiment has a high optical performance capable of favorably suppressing image blur and correcting various aberrations, and has a reduced size. Can be realized.

Further, it is desirable that the variable power optical system of the present embodiment satisfies the following conditional expression (1).
(1) 0.200 <f22 / ft <1.700
However,
f22: focal length of the 2b lens group ft: focal length of the entire variable power optical system in the telephoto end state

Conditional expression (1) is a conditional expression for defining an appropriate range for the ratio of the focal length of the 2b lens group, which is the image stabilizing lens group, to the focal length of the entire zoom optical system in the telephoto end state. It is. By satisfying the conditional expression (1), the variable power optical system of the present embodiment can be downsized and satisfactorily correct coma.

If the corresponding value of the conditional expression (1) of the variable power optical system of the present embodiment exceeds the upper limit, the refractive power of the second lens unit becomes weak, and the shift amount during vibration reduction increases, so that the size reduction is achieved. Not preferred in terms of surface. Further, coma aberration and field curvature are insufficiently corrected. By setting the upper limit of conditional expression (1) to 1.680, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (1) is set to 1.650, 1.630, 1.600, 1.580, 1.550, 1.530,. Preferably, it is 500, 1.480, and more preferably 1.450.

On the other hand, if the corresponding value of the conditional expression (1) of the variable power optical system of the present embodiment is below the lower limit, the refractive power of the 2b lens unit becomes strong, and it is not preferable because the position control during image stabilization becomes difficult. In addition, it becomes difficult to correct eccentric coma and coma aberration. By setting the lower limit of conditional expression (1) to 0.220, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the lower limit of conditional expression (1) is set to 0.240, 0.260, 0.280, 0.300, 0.320, 0.340,. It is preferably 360, 0.380, and more preferably 0.400.

Further, it is desirable that the variable power optical system of the present embodiment satisfies the following conditional expression (2).
(2) 0.150 <f21 / ft <2.000
However,
f21: focal length ft of the 2a-th lens unit: focal length of the entire variable power optical system in the telephoto end state

Conditional expression (2) is a conditional expression that defines an appropriate ratio between the focal length of the 2a-th lens unit and the focal length of the entire variable power optical system in the telephoto end state. The zoom optical system of the present embodiment can favorably correct spherical aberration and coma by satisfying conditional expression (2).

If the corresponding value of the conditional expression (2) of the variable power optical system of the present embodiment exceeds the upper limit, the refractive power of the second-a lens unit becomes weak, and it becomes difficult to correct spherical aberration and coma. By setting the upper limit of conditional expression (2) to 1.800, the effect of the present embodiment can be made more reliable. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (2) is set to 1.500, 1.300, 1.000, 0.980, 0.950, 0.930, 0. Preferably, it is 900, 0.880, and more preferably 0.850.

On the other hand, when the corresponding value of the conditional expression (2) of the variable power optical system according to the present embodiment falls below the lower limit, the refractive power of the second lens subunit increases, and spherical aberration and coma can be favorably corrected. Will be gone. By setting the lower limit of conditional expression (2) to 0.200, the effect of the present embodiment can be made more reliable. In order to further secure the effect of the present embodiment, the lower limit of conditional expression (2) is set to 0.220, 0.240, 0.260, 0.280, 0.300, 0.320, 0. It is preferably 340, 0.350, and more preferably 0.360.

In the zoom optical system according to the present embodiment, it is preferable that the second lens sub-unit is a cemented lens. Thereby, the variable power optical system of the present embodiment can satisfactorily correct chromatic aberration. In particular, arranging the 2a-th lens unit in the second lens unit near the stop is effective for correcting axial chromatic aberration.

は In the zoom optical system according to the present embodiment, it is preferable that the second lens group is a cemented lens. Thereby, the variable power optical system of the present embodiment can satisfactorily correct chromatic aberration. In particular, arranging the second lens group in the second lens group near the stop is effective for correcting axial chromatic aberration.

It is desirable that the zoom optical system of the present embodiment satisfies the following conditional expression (3).
(3) 1.00 <(− fγw) <2.00
However,
fγw: ratio of the amount of movement of the image plane to the amount of movement of the third lens group in the wide-angle end state

Conditional expression (3) is a conditional expression that defines the ratio of the amount of movement of the image plane to the amount of movement of the third lens unit that is the focusing lens unit in the wide-angle end state. The variable power optical system according to the present embodiment satisfies the conditional expression (3) to secure a necessary focus stroke and to reduce the size. Further, from the time of focusing on an object at infinity to the time of focusing on a close object. Can be satisfactorily corrected.

If the corresponding value of the conditional expression (3) of the variable power optical system of the present embodiment exceeds the upper limit, the refractive power of the third lens group, which is the focusing lens group, becomes strong, and it becomes difficult to control the focusing position. Not preferred. In addition, the fluctuation of the curvature of field becomes large, and the correction becomes difficult. By setting the upper limit of conditional expression (3) to 1.90, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (3) is set to 1.80, 1.75, 1.70, 1.68, 1.65, 1.62,. It is preferably 60, 1.58, and more preferably 1.55.

On the other hand, when the corresponding value of the conditional expression (3) of the variable power optical system according to the present embodiment is below the lower limit, the refractive power of the third lens group, which is the focusing lens group, becomes weak, and The amount of movement increases, which is not preferable in terms of miniaturization. In addition, it becomes impossible to satisfactorily correct the field curvature. By setting the lower limit of conditional expression (3) to 1.05, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the lower limit of conditional expression (3) is set to 1.10, 1.15, 1.18, 1.20, 1.21, and 1.22. Is preferred.

Further, it is desirable that the variable power optical system of the present embodiment satisfies the following conditional expression (4).
(4) 0.05 <f21 / f22 <3.00
However,
f21: focal length of the 2a-th lens group f22: focal length of the 2b-th lens group

Conditional expression (4) is a conditional expression for defining an appropriate ratio between the focal length of the second lens subunit and the focal length of the second lens subunit. In the zoom optical system according to the present embodiment, by satisfying the conditional expression (4), the power arrangement of the cemented lens of the second-a lens unit and the cemented lens of the second-b lens unit becomes appropriate, and over the entire zoom range. Chromatic aberration can be corrected well. In particular, arranging the cemented lens of the 2a lens group and the cemented lens of the 2b lens group in the second lens group near the stop is effective for correcting axial chromatic aberration.

When the corresponding value of the conditional expression (4) of the variable power optical system of the present embodiment exceeds the upper limit, the refractive power of the 2a-th lens unit becomes weak and the refractive power of the 2b-th lens unit becomes strong. This is not preferable because the balance of the chromatic aberration correction is lost. In particular, axial chromatic aberration on the telephoto side cannot be corrected well. By setting the upper limit of conditional expression (4) to 2.70, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit value of conditional expression (4) is set to 2.50, 2.20, 2.00, 1.95, 1.90, 1.85, 1. 82, 1.80, and more preferably 1.78.

On the other hand, when the corresponding value of the conditional expression (4) of the variable power optical system according to the present embodiment is below the lower limit, the refractive power of the 2a-th lens unit becomes strong, and the refractive power of the 2b-th lens unit becomes weak. It is not preferable because the balance of the chromatic aberration correction at the time of fluctuation is lost. In particular, axial chromatic aberration on the wide-angle side cannot be satisfactorily corrected. By setting the lower limit of conditional expression (4) to 0.08, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the lower limits of conditional expression (4) are set to 0.10, 0.13, 0.15, 0.18, 0.20, 0.23,. 24, 0.25, and more preferably 0.26.

In addition, it is desirable that the zoom optical system of the present embodiment satisfies the following conditional expression (5).
(5) 0.50 <(− f3) / fw <3.00
However,
f3: focal length of the third lens group fw: focal length of the entire variable power optical system in the wide-angle end state

Conditional expression (5) is a conditional expression that defines the ratio of the focal length of the third lens unit, which is the focusing lens unit, to the focal length of the entire variable power optical system in the wide-angle end state. The variable power optical system according to the present embodiment satisfies the conditional expression (5), secures a necessary focus stroke, reduces the size of the drive mechanism and structure of the focusing lens unit, and further focuses on an object at infinity. In the focal length range from the in-focus state to the in-focus state of a short-distance object, particularly in the focal length range on the wide-angle side, it is possible to satisfactorily correct the fluctuation of the field curvature.

If the corresponding value of the conditional expression (5) of the variable power optical system of the present embodiment exceeds the upper limit, the refractive power of the third lens unit, which is the focusing lens unit, becomes weak, and the amount of movement of the third lens unit increases. This is not preferable in terms of miniaturization. In addition, it becomes difficult to correct the field curvature in the focal length range on the wide-angle side. By setting the upper limit of conditional expression (5) to 2.80, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (5) is set to 2.50, 2.40, 2.30, 2.20, 2.10, 2.00, 1. 95, 1.90, and more preferably 1.85.

On the other hand, when the corresponding value of the conditional expression (5) of the variable power optical system according to the present embodiment falls below the lower limit, the refractive power of the third lens unit, which is the focusing lens unit, becomes strong, and the position control of the focusing lens unit is performed. Is not preferable because it becomes difficult. In addition, the fluctuation of the curvature of field becomes large, and the correction becomes difficult. By setting the lower limit of conditional expression (5) to 0.60, the effect of the present embodiment can be made more reliable. In order to further secure the effect of the present embodiment, the lower limits of conditional expression (5) are set to 0.70, 0.80, 0.90, 0.95, 1.00, 1.05,. It is preferably set to 10, 1.15, and more preferably 1.20.

In addition, it is desirable that the zoom optical system of the present embodiment satisfies the following conditional expression (6).
(6) 0.100 <G2 / TLt <0.500
However,
G2: Length on the optical axis of the second lens group TLt: Length on the optical axis of the entire variable power optical system in the telephoto end state

Conditional expression (6) is a conditional expression for defining an appropriate length on the optical axis of the second lens group. By satisfying conditional expression (6), the variable power optical system according to the present embodiment can achieve downsizing and satisfactorily correct spherical aberration and coma.

と When the corresponding value of conditional expression (6) of the variable power optical system of the present embodiment exceeds the upper limit, the second lens group becomes thick. In this case, the refractive power of the second lens group becomes weaker, the number of lenses that form the second lens group increases, or the thickness of the lenses that form the second lens group increases, resulting in an increase in size. This is not preferred. By setting the upper limit of conditional expression (6) to 0.450, the effect of the present embodiment can be made more reliable. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (6) is set to 0.400, 0.380, 0.350, 0.330, 0.300, 0.280, 0. Preferably, it is 260, 0.250, and more preferably 0.230.

On the other hand, when the corresponding value of the conditional expression (6) of the variable power optical system of the present embodiment falls below the lower limit, the second lens group becomes thin. In this case, the refracting power of the second lens group is increased, or the number of lenses constituting the second lens group is reduced. As a result, spherical aberration and coma cannot be satisfactorily corrected. By setting the lower limit of conditional expression (6) to 0.130, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the lower limit of conditional expression (6) is set to 0.140, 0.150, 0.160, 0.165, 0.170, 0.175, 0.1. It is preferably 180, 0.185, and more preferably 0.190.

In addition, it is desirable that the zoom optical system of the present embodiment satisfies the following conditional expression (7).
(7) 0.020 <G4 / TLt <0.200
However,
G4: Length on the optical axis of the fourth lens group TLt: Length on the optical axis of the entire variable power optical system in the telephoto end state

Conditional expression (7) is a conditional expression for defining an appropriate length on the optical axis of the fourth lens group. By satisfying conditional expression (7), the variable power optical system of the present embodiment can reduce the size and can satisfactorily correct the fluctuation of the curvature of field at the time of zoom fluctuation.

と If the corresponding value of the conditional expression (7) of the variable power optical system of the present embodiment exceeds the upper limit, the fourth lens group becomes thick. In this case, the refractive power of the fourth lens group becomes weak, or the number of lenses that form the fourth lens group increases, or the thickness of the lenses that form the fourth lens group increases, resulting in an increase in size. This is not preferred. By setting the upper limit of conditional expression (7) to 0.180, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (7) is set to 0.150, 0.130, 0.110, 0.100, 0.095, 0.092, 0. 090, 0.088, and more preferably 0.085.

On the other hand, when the corresponding value of the conditional expression (7) of the variable power optical system of the present embodiment is below the lower limit, the fourth lens group becomes thin. In this case, the refracting power of the fourth lens group becomes stronger, or the number of lenses constituting the fourth lens group decreases. As a result, it becomes impossible to satisfactorily correct the field curvature. By setting the lower limit of conditional expression (7) to 0.025, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the lower limits of conditional expression (7) are set to 0.030, 0.035, 0.040, 0.043, 0.045, 0.048, 0. 050, 0.053, and more preferably 0.055.

In the zoom optical system according to the present embodiment, it is preferable that the third lens group includes one lens component and satisfies the following conditional expression (8).
(8) -20.00 <R2f3 / R1f3 <-1.00
However,
R1f3: radius of curvature of the lens surface closest to the object side of the lens component R2f3: radius of curvature of the lens surface closest to the image side of the lens component

Conditional expression (8) is a conditional expression that defines the shape of one lens component constituting the third lens group. By satisfying conditional expression (8), the variable power optical system according to the present embodiment can suppress ghost and flare due to reflection on the lens surface, and can favorably correct curvature of field. The lens component refers to a cemented lens formed by combining two or more lenses, or a single lens.

When the corresponding value of the conditional expression (8) of the zoom optical system according to the present embodiment exceeds the upper limit, the lens component has a sharp concave curvature on the image surface side, and flare easily occurs on the image surface. turn into. By setting the upper limit of conditional expression (8) to -1.05, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limits of conditional expression (8) are set to −1.10, −1.15, −1.20, −1.30, −1.40, −1. It is preferable to set 1.50, −1.60, −1.70 and −1.80.

On the other hand, if the corresponding value of the conditional expression (8) of the variable power optical system of the present embodiment is below the lower limit, the effect of correcting the field curvature is reduced. By setting the lower limit of conditional expression (8) to -19.00, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the lower limits of conditional expression (8) are set to −18.00, −17.00, −16.00, −15.00, −14.00, −14. It is preferable to set them to 13.00, -12.00, -11.00 and -10.00.

は In the zoom optical system of the present embodiment, it is preferable that the third lens group has at least one aspheric surface. As a result, the drive mechanism and structure of the third lens group, which is the focusing lens group, are reduced in size, and the variation in curvature of field from the in-focus object state to the close-distance object state is effectively corrected. be able to.

In addition, it is desirable that the zoom optical system according to the present embodiment satisfies the following conditional expression (9).
(9) -16.00 <(-f23) / ft <5.00
However,
f23: focal length ft of the second lens group c: focal length of the entire variable power optical system in the telephoto end state

The conditional expression (9) is a conditional expression that defines the ratio of the focal length of the second c lens group to the focal length of the entire variable power optical system in the telephoto end state. By satisfying the conditional expression (9), the variable power optical system of the present embodiment can be reduced in size and can properly correct coma aberration and spherical aberration.

と If the corresponding value of the conditional expression (9) of the variable power optical system of the present embodiment exceeds the upper limit, the refractive power of the second lens unit c will be weak, and coma and spherical aberration will be insufficiently corrected. By setting the upper limit of conditional expression (9) to 4.60, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (9) is set to 4.30, 4.00, 3.50, 3.00, 2.80, 2.30, 2.30. 00, 1.80, and more preferably 1.50.

On the other hand, when the corresponding value of the conditional expression (9) of the variable power optical system according to the present embodiment is below the lower limit, the refractive power of the second lens unit c becomes strong, and coma aberration and spherical aberration are overcorrected. By setting the lower limit of conditional expression (9) to 0.10. The effect of the present embodiment can be made more reliable. In order to further secure the effect of the present embodiment, the lower limits of conditional expression (9) are set to 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0. It is preferably 45, 0.48, 0.50, and more preferably 0.53.

In addition, it is desirable that the zoom optical system of the present embodiment satisfies the following conditional expression (10).
(10) 50.0 ° <2ω <120.0 °
However,
2ω: Full field angle of the variable power optical system in the wide-angle end state

Conditional expression (10) is a condition for defining the optimum value of the angle of view. By satisfying conditional expression (10), the variable power optical system of the present embodiment can be reduced in size and satisfactorily corrected for various aberrations.

In order to secure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (10) to 115.0 °. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (10) is set to 110.0 °, 105.0 °, 100.0 °, 95.0 °, 92.0 °, 91 It is preferably set to 0.0 °, 90.0 °, 89.0 °, and more preferably 88.5 °.
In order to secure the effect of the present embodiment, it is preferable to set the lower limit of conditional expression (10) to 55.0 °. In order to further secure the effect of the present embodiment, the lower limit of conditional expression (10) is set to 60.0 °, 65.0 °, 70.0 °, 75.0 °, 78.0 °, 80 It is preferable to set the angle to 0.0 °, 82.0 °, 84.0 °, and more preferably 84.5 °.

In addition, it is desirable that the zoom optical system according to the present embodiment satisfies the following conditional expression (11).
(11) 0.20 <Bfa / fw <0.90
However,
Bfa: air-equivalent back focus of the entire zoom optical system in the wide-angle end state fw: focal length of the entire zoom optical system in the wide-angle end state

The conditional expression (11) is a conditional expression that defines the ratio between the air-equivalent back focus of the entire zoom optical system in the wide-angle end state and the focal length of the entire zoom optical system in the wide-angle end state. . By satisfying conditional expression (11), the variable power optical system of the present embodiment can be reduced in size and can favorably correct various aberrations.

If the value of the conditional expression (11) of the zoom optical system according to the present embodiment exceeds the upper limit, the back focus becomes longer, which is not preferable in miniaturization. By setting the upper limit of conditional expression (11) to 0.85, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (11) is set to 0.80, 0.78, 0.75, 0.73, 0.70, 0.68, 0. It is preferably 67, 0.66, and more preferably 0.65.

On the other hand, if the corresponding value of the conditional expression (11) of the variable power optical system of the present embodiment is below the lower limit, the back focus becomes short, and there is a concern of interference with the camera mechanism. By setting the lower limit of conditional expression (11) to 0.25, the effect of the present embodiment can be further ensured. In order to further secure the effect of the present embodiment, the upper limit of conditional expression (11) is set to 0.30, 0.35, 0.40, 0.42, 0.45, 0.48, 0. It is preferably 50, 0.52, and more preferably 0.55.

光学 The optical apparatus of the present embodiment has the variable power optical system having the above-described configuration. Accordingly, it is possible to realize an optical device having high optical performance capable of satisfactorily suppressing image blur and satisfactorily correcting various aberrations, and achieving downsizing.

The method of manufacturing the variable power optical system according to the present embodiment includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power. A method of manufacturing a variable power optical system having a lens group and a fourth lens group having a positive refractive power, wherein a distance between the first lens group and the second lens group changes during zooming. The distance between the second lens group and the third lens group is changed, and the distance between the third lens group and the fourth lens group is changed. In order from the second lens group having a positive refractive power, a second lens group having a positive refractive power, a second lens group having a negative refractive power, and a second lens group having a negative refractive power. Is moved so as to include a component in a direction perpendicular to the optical axis. Configured, during focusing, the third lens group is a manufacturing method of the variable magnification optical system configured to move in the optical axis direction.

Thereby, it is possible to manufacture a variable-magnification optical system having high optical performance capable of favorably suppressing image blur and satisfactorily correcting various aberrations, and achieving downsizing.

Hereinafter, a variable power optical system according to a numerical example of the embodiment will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a cross-sectional view of the variable power optical system according to Example 1 in a wide-angle end state. Arrows in FIG. 1 and FIGS. 3, 5, 7, 9, 11, and 13 to be described later indicate each lens at the time of zooming from the wide-angle end state (W) to the telephoto end state (T). The movement locus of the group is shown.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, 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 negative meniscus lens L11 is an aspheric lens in which a resin layer provided on the image side glass lens surface is formed in an aspheric shape.

The second lens group G2 includes, in order from the object side, a second-a lens group G2a having a positive refractive power, an aperture stop S, a second-b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power. 2c lens group G2c.

The second-a lens group G2a is composed of a cemented positive lens composed of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspheric lens having an aspheric lens surface on the object side.
The second-b lens unit G2b includes a cemented positive lens formed by a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The 2c-th lens unit G2c includes a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspheric lens having an aspheric lens surface on the object side.

The third lens group G3 includes a biconcave negative lens L31. The negative lens L31 is an aspheric lens in which the lens surface on the object side and the lens surface on the image side have an aspheric shape.
The fourth lens group G4 includes a positive meniscus lens L41 having a concave surface facing the object side.

(4) On the image plane I, an image pickup device (not shown) composed of a CCD, a CMOS, or the like is arranged.

With the above configuration, the zoom optical system according to the present embodiment reduces the distance between the first lens group G1 and the second lens group G2 when zooming from the wide-angle end state to the telephoto end state, The first lens group G1 and the second lens group G2 are arranged such that the distance between the second lens group G2 and the third lens group G3 increases, and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 moves along the optical axis. Specifically, the first lens group G1 once moves to the image side and then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. During zooming, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable power optical system according to the present embodiment focuses from an object at infinity to an object at a short distance by moving the third lens group G3 to the image side along the optical axis.

The variable power optical system according to this embodiment moves the second lens group G2b as the image stabilizing lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blur occurs, that is, image stabilization. I do.

Table 1 below shows values of specifications of the variable power optical system according to the present example.
In Table 1, f indicates the focal length, and BF indicates 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.
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 interval (the interval between the nth surface (n is an integer) and the (n + 1) th surface), and νd is the d line ( Abbe number for a wavelength of 587.6 nm), nd indicates a refractive index for a d-line (wavelength 587.6 nm), and ng indicates a refractive index for a g-line (wavelength 435.8 nm). OP is an object plane, dn (n is an integer) is a variable surface interval, S is an aperture stop, and I is an image plane. Note that the radius of curvature r = ∞ indicates a plane. The description of the refractive index nd of air = 1.0000 is omitted. When the lens surface is an aspherical surface, “*” is added to the surface number, and the paraxial radius of curvature is shown in the column of the radius of curvature r.

[Aspherical surface data] shows an aspherical surface coefficient and a conical constant when the shape of the aspherical surface shown in [surface data] is represented by the following equation.
S (y) = (y ² / R) / [1+ {1-κ (y / R) ² } ^1/2 ]
^{^{+ C4y 4 + C6y 6 + C8y}} 8 + C 10y 10
Here, y is the height in the direction perpendicular to the optical axis, S (y) is the sag amount which is the distance along the optical axis from the tangent plane of the vertex of the aspheric surface at the height y to the aspheric surface, κ Is the conic constant, C4, C6, C8, C10, C12, and C14 are the aspherical coefficients, and R is the paraxial radius of curvature, which is the radius of curvature of the reference spherical surface. Note that “E−n” (n: an integer) indicates “× 10 ⁻ⁿ ”, and “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”. The second-order aspheric coefficient C2 is 0, and the description is omitted.

In [various data], f is the focal length of the entire optical system, FNo is the F number, 2ω is the angle of view (unit is “°”), Ymax is the maximum image height, and TL is the variable power optical system according to the present embodiment. BF indicates 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. W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

In [variable interval data], f indicates the focal length of the entire optical system, and dn (n is an integer) indicates the variable interval between the n-th surface and the (n + 1) -th surface. W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.
[Lens group data] shows the starting surface number ST and the focal length f of each lens group.
[Conditional expression corresponding value] shows the corresponding value of each conditional expression.

Here, “mm” is generally used as the unit of the focal length f, the radius of curvature r, and other lengths described in Table 1. However, the optical system is not limited to this, since the same optical performance can be obtained even if the optical system is enlarged or reduced proportionally.
The reference numerals in Table 1 described above are used in the same manner in the tables of the respective embodiments described later.

(Table 1) First Example [Surface Data]
mr d νd nd ng
OP ∞
1) 125.7973 1.20 42.73 1.834810 1.859557
2) 13.4148 0.10 36.64 1.560930 1.580890
* 3) 12.2663 4.97
4) 17.5162 2.47 20.88 1.922860 1.982814
5) 25.3582 (d5)

* 6) 19.6694 1.00 37.28 1.834410 1.863105
7) 14.6517 3.30 52.33 1.755000 1.772953
8) 162.3331 1.50
9) (S) ∞ 1.90
10) 9.4378 0.70 32.32 1.953747 1.992060
11) 6.7335 4.00 81.61 1.496997 1.504509
12) -32.9446 1.40
* 13) 18.1461 0.90 45.45 1.801387 1.823574
14) 9.6929 (d14)

* 15) -34.3749 1.00 45.45 1.801387 1.823574
* 16) 40.0000 (d16)

17) -176.2842 4.50 32.32 1.953747 1.992060
18) -28.4688 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 5.57659E-05 1.55222E-07 -1.40739E-10 6.89982E-13
6 1.0000 -1.51464E-05 -2.85919E-08 -4.84293E-10 -8.67521E-12
13 1.0000 -7.39652E-05 -1.64020E-06 1.08994E-07 -1.80154E-09
15 1.0000 -2.45378E-04 2.50287E-06 -2.00932E-08 1.64201E-10
16 1.0000 -2.07691E-04 2.92258E-06 -2.50531E-08 1.04781E-10

[Various data]
Zoom ratio 2.94
W M T
f 16.48 35.00 48.50
FNo 3.61 5.25 6.36
2ω 88.11 42.86 32.15
Ymax 14.20 14.20 14.20
TL 71.96 65.66 69.91
BF 9.90 9.90 9.90

[Variable interval data]
W M T
f 16.48 35.00 48.50
d5 24.17 6.25 2.00
d14 5.33 10.82 13.69
d16 3.62 9.75 14.82

[Lens group data]
ST f
G1 1 -26.45
G2 6 17.88
G3 15 -22.93
G4 17 35.08
G2a 6 30.39
G2b 10 20.50
G2c 13 -27.26

[Values for conditional expressions]
(1) f22 / ft = 0.423
(2) f21 / ft = 0.627
(3) (−fγw) = 1.300
(4) f21 / f22 = 1.482
(5) (−f3) /fw=1.392
(6) G2 / TLt = 0.210
(7) G4 / TLt = 0.064
(8) R2f3 / R1f3 = -1.164
(9) (−f23) /ft=0.562
(10) 2ω = 88.110
(11) Bfa / fw = 0.601

FIGS. 2A and 2B are graphs showing various aberrations of the variable power optical system according to Example 1 in the wide-angle end state and the telephoto end state, respectively.

収差 In each aberration diagram, FNO represents an F-number, and A represents a light incident angle, that is, a half angle of view (unit is “°”). The spherical aberration diagram shows the value of the F-number FNO with respect to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum value of the half angle of view A, and the coma diagram shows the value of each half angle of view. In each aberration diagram, d indicates aberration at d line (wavelength 587.6 nm), g indicates aberration at g line (wavelength 435.8 nm), and those without d and g indicate aberration at d line. In the astigmatism diagram, a solid line indicates a sagittal image plane, and a broken line indicates a meridional image plane. The coma aberration diagram shows the coma aberration at each half angle of view A. Note that the same reference numerals as in the present embodiment are used in the aberration diagrams of each embodiment described later.

From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state.

(Second embodiment)
FIG. 3 is a cross-sectional view of the zoom optical system according to Example 2 in a wide-angle end state.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The second-a lens group G2a is composed of a cemented positive lens composed of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspheric lens having an aspheric lens surface on the object side.
The second-b lens unit G2b includes a cemented positive lens including a negative meniscus lens L23 having a convex surface facing the object side and a positive meniscus lens L24 having a convex surface facing the object side.
The 2c-th lens group G2c includes a biconcave negative lens L25. The negative lens L25 is an aspheric lens having an aspheric lens surface on the object side.

The variable power optical system according to the present embodiment focuses from an object at infinity to an object at a short distance by moving the third lens group G3 toward the object image along the optical axis.

表 Table 2 below shows values of specifications of the variable power optical system according to the present example.

(Table 2) Second Example [Surface Data]
mr d νd nd ng
OP ∞
1) 234.3978 1.20 42.73 1.834810 1.859557
2) 13.5837 0.20 36.64 1.560930 1.580890
* 3) 12.5840 4.97
4) 19.3856 2.47 20.88 1.922860 1.982814
5) 30.2795 (d5)

* 6) 12.2620 1.00 37.28 1.834410 1.863105
7) 7.4723 3.30 52.33 1.755000 1.772953
8) 37.8448 1.50
9) (S) ∞ 2.10
10) 10.8585 0.70 32.32 1.953747 1.992060
11) 7.4800 4.00 81.61 1.496997 1.504509
12) 48.7880 1.40
* 13) -222.1192 0.90 45.45 1.801387 1.823574
14) 322.4924 (d14)

* 15) -22.1912 1.00 45.45 1.801387 1.823574
* 16) 150.0000 (d16)

17) -140.0701 4.15 32.32 1.953747 1.992060
18) -28.8384 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 4.03793E-05 7.56897E-08 -3.47835E-10 4.74887E-13
6 1.0000 -5.40717E-06 -1.52719E-07 3.78212E-09 -3.33602E-11
13 1.0000 -1.53164E-04 4.41893E-07 -9.85968E-08 2.04214E-09
15 1.0000 2.96657E-05 -2.21789E-07 1.10487E-08 -4.19378E-11
16 1.0000 6.42683E-05 -2.63833E-07 5.05296E-09 -2.24350E-11

[Various data]
Zoom ratio 2.94
W M T
f 16.48 35.00 48.50
FNo 3.52 5.08 6.31
2ω 88.00 42.70 31.75
Ymax 14.20 14.20 14.20
TL 72.25 65.75 69.84
BF 9.90 9.90 9.90

[Variable interval data]
W M T
f 16.48 35.00 48.50
d5 24.58 6.37 2.00
d14 5.33 11.53 14.97
d16 3.55 9.06 13.53

[Lens group data]
ST f
G1 1 -25.80
G2 6 18.42
G3 15 -24.06
G4 17 37.40
G2a 6 24.53
G2b 10 51.00
G2c 13 -164.01

[Values for conditional expressions]
(1) f22 / ft = 1.052
(2) f21 / ft = 0.506
(3) (−fγw) = 1.250
(4) f21 / f22 = 0.481
(5) (−f3) /fw=1.460
(6) G2 / TLt = 0.213
(7) G4 / TLt = 0.059
(8) R2f3 / R1f3 = -6.759
(9) (−f23) /ft=3.382
(10) 2ω = 88.000
(11) Bfa / fw = 0.601

4A and 4B are graphs showing various aberrations of the variable power optical system according to Example 2 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

(Third embodiment)
FIG. 5 is a cross-sectional view of the zoom optical system according to Example 3 at the wide-angle end.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The third lens group G3 includes a biconcave negative lens L31. The negative lens L31 is an aspheric lens in which the lens surface on the object side and the lens surface on the image side have an aspheric shape.
The fourth lens group G4 includes a positive meniscus lens L41 having a concave surface facing the object side, and a biconvex positive lens L42.

表 Table 3 below shows values of specifications of the variable power optical system according to the present example.

(Table 3) Third Example [Surface Data]
mr d νd nd ng
OP ∞
1) 415.8197 1.20 42.73 1.834810 1.859557
2) 13.9397 0.20 36.64 1.560930 1.580890
* 3) 12.2524 5.76
4) 23.3129 2.50 20.88 1.922860 1.982814
5) 45.3700 (d5)

* 6) 14.1993 1.00 37.28 1.834410 1.863105
7) 8.4743 3.30 52.33 1.755000 1.772953
8) 69.9056 1.50
9) (S) ∞ 2.30
10) 12.4272 0.70 32.32 1.953747 1.992060
11) 8.3425 4.10 81.61 1.496997 1.504509
12) -66.3702 1.20
* 13) 25.4896 0.90 45.45 1.801387 1.823574
14) 13.6978 (d14)

* 15) -29.0995 1.00 45.45 1.801387 1.823574
* 16) 117.1841 (d16)

17) -116.7933 3.27 32.32 1.953747 1.992060
18) -36.3587 0.50
19) 971.6152 2.00 32.32 1.953747 1.992060
20) -167.5953 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 2.01514E-05 7.60272E-08 -8.33546E-10 1.57294E-12
6 1.0000 -1.19935E-05 -7.39414E-08 1.06814E-09 -8.74368E-12
13 1.0000 -9.48763E-05 -1.20944E-07 -3.50716E-08 7.10609E-10
15 1.0000 -1.33067E-04 2.79113E-06 -1.66578E-08 -3.03507E-11
16 1.0000 -9.59859E-05 2.68605E-06 -2.60631E-08 8.24910E-11

[Various data]
Zoom ratio 2.94
W M T
f 16.48 35.00 48.50
FNo 3.62 5.37 6.60
2ω 85.97 42.77 31.70
Ymax 14.20 14.20 14.20
TL 74.46 70.08 74.92
BF 9.55 9.55 9.55

[Variable interval data]
W M T
f 16.48 35.00 48.50
d5 24.44 6.57 2.05
d14 5.30 10.52 13.64
d16 3.74 12.01 17.71

[Lens group data]
ST f
G1 1 -26.74
G2 6 19.27
G3 15 -29.00
G4 17 39.98
G2a 6 24.85
G2b 10 33.00
G2c 13 -38.25

[Values for conditional expressions]
(1) f22 / ft = 0.680
(2) f21 / ft = 0.512
(3) (−fγw) = 1.250
(4) f21 / f22 = 0.753
(5) (−f3) /fw=1.760
(6) G2 / TLt = 0.200
(7) G4 / TLt = 0.077
(8) R2f3 / R1f3 = -4.027
(9) (−f23) /ft=0.789
(10) 2ω = 85.970
(11) Bfa / fw = 0.579

6A and 6B are aberration diagrams of the variable power optical system according to Example 3 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

(Fourth embodiment)
FIG. 7 is a cross-sectional view of the zoom optical system according to Example 4 at the wide-angle end.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The second lens group G2 includes, in order from the object side, a second-a lens group G2a having a positive refractive power, an aperture stop S, a second-b lens group G2b having a positive refractive power, and a second lens group G2b having a positive refractive power. 2c lens group G2c.

The second-a lens group G2a is composed of a cemented positive lens composed of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspheric lens having an aspheric lens surface on the object side.
The second-b lens unit G2b includes a cemented positive lens formed by a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second lens group G2c includes a positive meniscus lens L25 having a convex surface facing the object side. The positive meniscus lens L25 is an aspheric lens having an aspheric lens surface on the object side.

With the above configuration, the zoom optical system according to the present embodiment reduces the distance between the first lens group G1 and the second lens group G2 when zooming from the wide-angle end state to the telephoto end state, The first lens group G1 and the second lens group G2 are arranged such that the distance between the second lens group G2 and the third lens group G3 increases, and the distance between the third lens group G3 and the fourth lens group G4 increases. Then, the third lens group G3 and the fourth lens group G4 move along the optical axis. Specifically, the first lens group G1 once moves to the image side and then moves to the object side, the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, and the fourth lens group G3 moves to the object side. The lens group G4 once moves to the object side, and then moves to the image side.

Table 4 below shows the values of the specifications of the variable power optical system according to this example.

(Table 4) Fourth Embodiment [Surface Data]
mr d νd nd ng
OP ∞
1) 169.1820 1.20 42.73 1.834810 1.859557
2) 13.8308 0.10 36.64 1.560930 1.580890
* 3) 12.7005 4.70
4) 18.7978 2.47 20.88 1.922860 1.982814
5) 28.2383 (d5)

* 6) 15.6168 1.10 37.28 1.834410 1.863105
7) 10.3108 3.00 52.33 1.755000 1.772953
8) 202.8228 1.50
9) (S) ∞ 2.30
10) 57.1584 1.10 32.32 1.953747 1.992060
11) 15.9047 3.50 81.61 1.496997 1.504509
12) -19.4256 1.40
* 13) 9.6189 1.10 45.45 1.801387 1.823574
14) 9.2769 (d14)

* 15) -22.2675 1.10 45.45 1.801387 1.823574
* 16) 150.0000 (d16)

17) -114.9236 4.0000 32.32 1.953747 1.992060
18) -30.5298 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 4.01896E-05 8.69299E-08 -1.62310E-10 -1.75455E-13
6 1.0000 -2.32045E-05 -3.43812E-07 7.11770E-09 -8.59494E-11
13 1.0000 -4.01902E-05 4.96254E-07 -5.88669E-08 1.11602E-09
15 1.0000 5.77251E-05 -2.91771E-06 5.88232E-08 -3.04864E-10
16 1.0000 1.05257E-04 -2.44529E-06 4.19957E-08 -2.44101E-10

[Various data]
Zoom ratio 2.95
W M T
f 16.48 34.95 48.56
FNo 3.49 5.18 6.72
2ω 87.61 43.00 32.11
Ymax 14.20 14.20 14.20
TL 72.45 67.01 71.17
BF 9.55 9.89 8.71

[Variable interval data]
W M T
f 16.48 34.95 48.56
d5 23.92 5.99 2.00
d14 7.15 11.38 13.40
d16 3.26 11.18 18.49

[Lens group data]
ST f
G1 1 -26.46
G2 6 18.55
G3 15 -24.13
G4 17 42.61
G2a 6 23.44
G2b 10 70.00
G2c 13 755.63

[Values for conditional expressions]
(1) f22 / ft = 1.442
(2) f21 / ft = 0.483
(3) (−fγw) = 1.260
(4) f21 / f22 = 0.335
(5) (−f3) /fw=1.466
(6) G2 / TLt = 0.111
(7) G4 / TLt = 0.056
(8) R2f3 / R1f3 = -6.736
(9) (-f23) /ft=-15.561
(10) 2ω = 87.610
(11) Bfa / fw = 0.580

8A and 8B are graphs showing various aberrations of the variable power optical system according to Example 4 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

(Fifth embodiment)
FIG. 9 is a sectional view of a variable power optical system according to Example 5 in a wide-angle end state.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The third lens group G3 includes a biconcave negative lens L31. The negative lens L31 is an aspheric lens in which the lens surface on the object side and the lens surface on the image side have an aspheric shape.
The fourth lens group G4 includes a biconvex positive lens L41.

Table 5 below shows the values of the specifications of the variable power optical system according to this example.

(Table 5) Fifth Embodiment [Surface Data]
mr d νd nd ng
OP ∞
1) 149.5188 1.20 42.73 1.834810 1.859557
2) 13.5237 0.10 36.64 1.560930 1.580890
* 3) 12.2879 4.97
4) 18.9482 2.47 20.88 1.922860 1.982814
5) 28.9505 (d5)

* 6) 13.5032 1.00 37.28 1.834410 1.863105
7) 11.0874 3.30 54.61 1.729160 1.745716
8) 22.3650 1.50
9) (S) ∞ 1.92
10) 8.9895 0.70 32.32 1.953747 1.992060
11) 6.4452 4.40 81.61 1.496997 1.504509
12) -92.6886 1.50
* 13) 12.5893 0.90 45.45 1.801387 1.823574
14) 10.8067 (d14)

* 15) -25.9570 1.00 45.45 1.801387 1.823574
* 16) 50.0000 (d16)

17) 9009.6763 4.17 32.32 1.953747 1.992060
18) -37.5109 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 4.47610E-05 3.37093E-08 2.20559E-10 -1.76168E-12
6 1.0000 -6.44422E-06 -3.63219E-07 1.03860E-08 -1.25875E-10
13 1.0000 -1.14297E-04 6.12084E-07 -7.62496E-08 2.35513E-09
15 1.0000 -1.32259E-04 3.59497E-06 -3.34480E-08 6.16335E-11
16 1.0000 -8.78501E-05 3.61823E-06 -5.19557E-08 2.89309E-10

[Various data]
Zoom ratio 2.94
W M T
f 16.48 35.00 48.50
FNo 3.55 5.17 6.40
2ω 87.39 42.95 31.90
Ymax 14.20 14.20 14.20
TL 72.45 67.65 72.40
BF 10.45 10.45 10.45

[Variable interval data]
W M T
f 16.48 35.00 48.50
d5 23.92 6.34 2.00
d14 5.33 9.36 11.50
d16 3.62 12.37 18.77

[Lens group data]
ST f
G1 1 -26.19
G2 6 17.89
G3 15 -21.20
G4 17 39.18
G2a 6 41.00
G2b 10 23.54
G2c 13 -122.82

[Values for conditional expressions]
(1) f22 / ft = 0.485
(2) f21 / ft = 0.845
(3) (−fγw) = 1.530
(4) f21 / f22 = 1.742
(5) (−f3) /fw=1.286
(6) G2 / TLt = 0.210
(7) G4 / TLt = 0.058
(8) R2f3 / R1f3 = -1.926
(9) (−f23) /ft=2.532
(10) 2ω = 87.390
(11) Bfa / fw = 0.634

10A and 10B are graphs showing various aberrations of the variable power optical system according to Example 5 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

(Sixth embodiment)
FIG. 11 is a cross-sectional view of the zoom optical system according to Example 6 in the wide-angle end state.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The 2a-th lens group G2a is composed of a cemented positive lens composed of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22. The negative meniscus lens L21 is an aspheric lens having an aspheric lens surface on the object side.
The second-b lens unit G2b includes a cemented positive lens formed by a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The 2c-th lens unit G2c includes a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspheric lens having an aspheric lens surface on the object side.

The third lens group G3 includes a biconcave negative lens L31. The negative lens L31 is an aspheric lens in which the lens surface on the object side and the lens surface on the image side have an aspheric shape.
The fourth lens group G4 includes a negative meniscus lens L41 having a concave surface facing the object side, and a positive meniscus lens L42 having a concave surface facing the object side.

表 Table 6 below shows values of specifications of the variable power optical system according to this example.

(Table 6) Sixth embodiment [Surface data]
mr d νd nd ng
OP ∞
1) 100.8418 1.20 42.73 1.834810 1.859557
2) 12.6574 0.20 36.64 1.560930 1.580890
* 3) 10.9951 7.05
4) 21.4532 2.40 20.88 1.922860 1.982814
5) 34.1160 (d18)

* 6) 14.6028 1.00 40.10 1.851348 1.878369
7) 9.8130 3.50 52.33 1.755000 1.772953
8) -124.9828 1.50
9) (S) ∞ 1.80
10) 31.6130 0.70 32.32 1.953747 1.992060
11) 11.2300 4.50 81.61 1.496997 1.504509
12) -20.4731 1.20
* 13) 34.6235 0.90 45.45 1.801387 1.823574
14) 18.4344 (d14)

* 15) -25.6503 1.00 45.45 1.801387 1.823574
* 16) 390.0000 (d16)

17) -25.2964 1.50 32.32 1.953747 1.992060
18) -32.1124 0.64
19) -1068.6691 4.20 35.25 1.910822 1.944117
20) -34.4895 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 3.08194E-05 2.92185E-07 -3.02179E-09 9.34877E-12
6 1.0000 -3.64228E-05 -1.27201E-07 2.00483E-09 -3.50116E-11
13 1.0000 -6.42989E-05 -9.13900E-07 2.69556E-08 -7.03374E-10
15 1.0000 2.23810E-04 -8.52167E-06 1.38799E-07 -7.68675E-10
16 1.0000 2.33871E-04 -7.26776E-06 1.11301E-07 -6.25541E-10

[Various data]
Zoom ratio 2.94
W M T
f 16.48 35.00 48.50
FNo 3.70 5.59 6.81
2ω 85.43 43.27 32.13
Ymax 14.20 14.20 14.20
TL 76.46 71.98 77.00
BF 9.56 9.56 9.56

[Variable interval data]
W M T
f 16.48 35.00 48.50
d5 23.90 6.32 2.00
d14 5.30 9.97 12.52
d16 4.41 12.84 19.09

[Lens group data]
ST f
G1 1 -24.38
G2 6 18.89
G3 15 -30.00
G4 17 50.67
G2a 6 18.50
G2b 10 68.10
G2c 13 -50.44

[Values for conditional expressions]
(1) f22 / ft = 1.404
(2) f21 / ft = 0.381
(3) (−fγw) = 1.230
(4) f21 / f22 = 0.272
(5) (−f3) /fw=1.821
(6) G2 / TLt = 0.196
(7) G4 / TLt = 0.082
(8) R2f3 / R1f3 = -15.205
(9) (−f23) /ft=1.040
(10) 2ω = 85.430
(11) Bfa / fw = 0.580

12A and 12B are graphs showing various aberrations of the variable power optical system according to Example 6 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

(Seventh embodiment)
FIG. 13 is a sectional view of the zoom optical system according to Example 7 in the wide-angle end state.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

The second-a lens group G2a is composed of a cemented positive lens composed of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspheric lens having an aspheric lens surface on the object side.
The second-b lens unit G2b includes a cemented positive lens formed by a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c includes a negative meniscus lens L25 having a convex surface facing the object side, and a negative meniscus lens L26 having a convex surface facing the object side. The negative meniscus lens L25 is an aspheric lens having an aspheric lens surface on the object side.

表 Table 7 below shows values of specifications of the variable power optical system according to the present example.

(Table 7) Seventh embodiment [Surface data]
mr d νd nd ng
OP ∞
1) 318.1940 1.2000 42.73 1.834810 1.859557
2) 13.3339 0.1146 36.64 1.560930 1.580890
* 3) 11.8585 4.9800
4) 20.3293 2.5326 20.88 1.922860 1.982814
5) 36.1595 (d5)

* 6) 16.0234 1.0000 37.28 1.834410 1.863105
7) 11.8242 3.3000 52.33 1.755000 1.772953
8) 46.9472 1.5000
9) (S) ∞ 2.1000
10) 10.4476 0.7000 32.32 1.953747 1.992060
11) 7.2259 4.0000 81.61 1.496997 1.504509
12) -29.7417 1.4000
* 13) 15.1738 0.8000 45.45 1.801387 1.823574
14) 10.8696 0.6000
15) 151.5835 0.8000 47.35 1.788000 1.808889
16) 48.2029 (d16)

* 17) -21.9436 1.0000 45.45 1.801387 1.823574
* 18) 250.0319 (d18)

19) -412.1948 4.5000 32.32 1.953747 1.992060
20) -31.6185 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 3.36194E-05 6.64302E-08 -5.94762E-10 7.09446E-13
6 1.0000 -1.51373E-05 -1.50803E-07 2.94929E-09 -4.78160E-11
13 1.0000 -8.76066E-05 2.15101E-07 -3.75172E-08 1.39218E-09
17 1.0000 4.14606E-05 2.35903E-07 -2.11292E-08 3.33497E-10
18 1.0000 7.60623E-05 -2.20545E-07 -8.35741E-09 1.26712E-10

[Various data]
Zoom ratio 2.95
W M T
f 16.45 35.00 48.50
FNo 3.67 5.42 6.52
2ω 86.08 42.51 31.54
Ymax 14.20 14.20 14.20
TL 73.45 69.38 73.24
BF 10.05 10.05 10.05

[Variable interval data]
W M T
f 16.45 35.00 48.50
d5 23.92 6.72 2.05
d16 5.33 10.92 14.92
d18 3.62 11.16 15.15

[Lens group data]
ST f
G1 1 -25.63
G2 6 18.70
G3 17 -25.13
G4 19 35.70
G2a 6 31.95
G2b 10 22.24
G2c 13 -33.00

[Values for conditional expressions]
(1) f11 / f1 = 0.599
(2) f12 / (− f1) = 1.823
(3) f22 / ft = 0.459
(4) f21 / ft = 0.659
(5) (−fγw) = 1.180
(6) f21 / f22 = 1.437
(7) (−f3) /fw=1.528
(8) G2 / TLt = 0.221
(9) G4 / TLt = 0.061
(10) R2f3 / R1f3 = -11.394
(11) (−f23) /ft=0.687
(12) 2ω = 86.080
(13) Bfa / fw = 0.611

14A and 14B are graphs showing various aberrations of the variable power optical system according to Example 7 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

(Eighth embodiment)
FIG. 15 is a cross-sectional view of the zoom optical system according to Example 8 in the wide-angle end state.
The variable power optical system according to this example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group G2 having a negative refractive power. It comprises a lens group G3 and a fourth lens group G4 having a positive refractive power.

(Table 7) Seventh embodiment [Surface data]
mr d νd nd ng
OP ∞
1) 164.2409 1.20 42.73 1.834810 1.859557
2) 13.2012 0.12 36.64 1.560930 1.580890
* 3) 11.5762 4.97
4) 19.9548 2.43 20.88 1.922860 1.982810
5) 34.9021 (d5)

* 6) 14.5813 0.90 37.28 1.834410 1.863100
7) 9.2500 3.36 52.34 1.755000 1.772953
8) 52.3705 1.60
9) (S) ∞ 2.00
10) 11.1735 0.70 32.33 1.953750 1.992059
11) 7.6414 4.00 81.61 1.497000 1.504510
12) -45.2316 1.40
* 13) 19.2894 0.90 45.25 1.795256 1.817388
14) 11.9890 (d14)

* 15) -29.6878 1.00 45.46 1.801390 1.823570
* 16) 56.3004 (d16)

17) -345.3773 4.20 32.33 1.953750 1.992059
18) -32.7802 (BF)
I ∞

[Aspheric data]
m K C 4 C 6 C 8 C10
3 0.0000 3.80785E-05 3.24996E-08 -7.75872E-11 -1.57872E-12
6 1.0000 -1.40463E-05 -4.76006E-08 2.18077E-10 -1.70904E-11
13 1.0000 -8.28392E-05 -8.50079E-07 1.22452E-08 -3.42932E-11
15 1.0000 -1.28382E-04 4.23515E-06 -9.86336E-08 1.12907E-09
16 1.0000 -8.33049E-05 3.48272E-06 -6.94588E-08 6.14665E-10

[Various data]
Zoom ratio 2.95
W M T
f 16.46 35.04 48.50
FNo 3.56 5.35 6.36
2ω 84.69 42.54 31.81
Ymax 14.20 14.20 14.20
TL 71.75 66.94 71.27
BF 10.05 10.05 10.05

[Variable interval data]
W M T
f 16.46 35.04 48.50
d5 23.92 6.40 2.00
d14 5.34 10.17 13.02
d16 3.66 11.54 16.92

[Lens group data]
ST f
G1 1 -26.32
G2 6 18.31
G3 15 -24.13
G4 17 37.73
G2a 6 27.61
G2b 10 26.84
G2c 13 -42.13

[Values for conditional expressions]
(1) f22 / ft = 0.553
(2) f21 / ft = 0.569
(3) (−fγw) = 1.250
(4) f21 / f22 = 1.029
(5) (−f3) /fw=1.466
(6) G2 / TLt = 0.208
(7) G4 / TLt = 0.059
(8) R2f3 / R1f3 = -1.896
(9) (-f23) /ft=0.869
(10) 2ω = 84.690
(11) Bfa / fw = 0.638

16A and 16B are graphs showing various aberrations of the variable power optical system according to Example 8 in the wide-angle end state and the telephoto end state, respectively.
From the various aberration diagrams, it can be seen that the variable power optical system according to the present example has excellent imaging performance by favorably correcting various aberrations from the wide-angle end state to the telephoto end state.

According to each of the above embodiments, a variable-magnification optical system having high optical performance capable of satisfactorily correcting image aberrations from the wide-angle end state to the telephoto end state, and achieving miniaturization is provided. Can be realized.

The above embodiments are merely examples of the present invention, and the present invention is not limited to these embodiments. The following contents can be appropriately adopted as long as the optical performance of the variable power optical system of the present embodiment is not impaired.

Although a numerical example of the variable power optical system according to the present embodiment has a four-group configuration, the present embodiment is not limited to this, and a variable power optical system having another group configuration (for example, five groups) is configured. You can also. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image side of the variable power optical system of each of the above embodiments may be used. Alternatively, a lens or a lens group may be added between adjacent lens groups.

In each of the above embodiments, the third lens is a 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, for example, an ultrasonic motor, a stepping motor, a VCM motor, or the like.

In each of the above embodiments, the 2b lens group is a vibration-proof lens group. However, the present invention is not limited to this, and any or all of the lens groups may be used as a vibration-proof lens group perpendicular to the optical axis. It is also possible to adopt a configuration in which vibration is prevented by moving the component so as to include a directional component, or by rotating (swinging) in an in-plane direction including the optical axis.

The aperture stop of the variable power optical system in each of the above embodiments may be configured so that a role is substituted by a lens frame without providing a member as an aperture stop.

Also, the lens surface of the lens constituting the variable power optical system of each of the above embodiments may be spherical, flat, or aspheric. When the lens surface is a spherical surface or a flat surface, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is displaced, it is preferable because the deteriorating performance is small. When the lens surface is an aspherical surface, any of an aspherical surface by grinding, a glass molded aspherical surface obtained by molding glass into an aspherical shape by a mold, and a composite aspherical surface formed by forming a resin provided on a glass surface into an aspherical shape are used. Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In addition, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the zoom optical system in each of the above embodiments. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.

Next, a camera equipped with a variable power optical system according to the present embodiment will be described with reference to FIG.
FIG. 17 is a diagram illustrating a configuration of a camera including a variable power optical system according to the present embodiment.
As shown in FIG. 17, a camera 1 is an interchangeable lens mirrorless camera provided with the variable power optical system according to the first embodiment as the taking lens 2.

In the camera 1, light from an object (not shown) not shown is condensed by a photographing lens 2, and passes through an OLPF (Optical low pass filter) not shown on an imaging surface of an imaging unit 3. To form a subject image. Then, the subject image is photoelectrically converted by a photoelectric conversion element provided in the imaging unit 3, and an image of the subject is generated. This image is displayed on an EVF (Electronic view finder) 4 provided in the camera 1. Thus, the photographer can observe the subject via the EVF 4.
When the release button (not shown) is pressed by the photographer, the image of the subject generated by the imaging unit 3 is stored in the memory (not shown). In this way, the photographer can photograph the subject with the camera 1.

Here, as described above, the variable power optical system according to the first embodiment mounted on the camera 1 as the photographing lens 2 suppresses the image blur satisfactorily and improves various aberrations from the wide-angle end state to the telephoto end state. It has high optical performance that can be corrected to a small size, and is downsized. That is, the camera 1 has high optical performance capable of favorably suppressing image blur, favorably correcting various aberrations, and realizing miniaturization. Note that the same effects as those of the camera 1 can be obtained even if a camera equipped with the variable power optical system according to the second to eighth embodiments as the taking lens 2 is configured. Further, even when the variable power optical system according to each of the above-described embodiments is mounted on a single-lens reflex camera that has a quick return mirror and observes a subject with a viewfinder optical system, the same effect as that of the camera 1 can be obtained. it can.

Next, an outline of a method of manufacturing the variable power optical system of the present embodiment will be described with reference to FIG.
FIG. 18 is a flowchart showing an outline of the method of manufacturing the optical system according to the present embodiment.
The method of manufacturing an optical system according to the present embodiment shown in FIG. 18 includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a negative lens power. A method of manufacturing a variable power optical system having a third lens group and a fourth lens group having a positive refractive power, including the following steps S1 to S4.

Step S1: At the time of 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 The distance from the fourth lens group is changed.
Step S2: the second lens group includes, in order from the object side, a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power. It consists of.
Step S3: Image blur is corrected by moving the 2b lens group so as to include a component in a direction perpendicular to the optical axis.
Step S4: At the time of focusing, the third lens group is configured to move in the optical axis direction.

According to the manufacturing method of the variable power optical system according to the present embodiment, the variable power optical system has high optical performance capable of favorably suppressing image blur and excellently correcting various aberrations, and is reduced in size. A system can be manufactured.

G1 first lens group G2 second lens group G3 third lens group G4 fourth lens group G2a 2a lens group
G2b 2b lens group G2c 2c lens group S Aperture stop I Image plane 1 Camera 2 Photographing lens

Claims

In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power Group 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 fourth lens group change. The distance from the lens group changes,
The second lens group includes, in order from the object side, a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power,
The image blur is corrected by moving the second lens group so as to include a component in a direction perpendicular to the optical axis,
A variable power optical system in which the third lens group moves in the optical axis direction during focusing.
The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
0.200 <f22 / ft <1.700
However,
f22: focal length of the 2b lens group ft: focal length of the entire variable power optical system in the telephoto end state
3. The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
0.150 <f21 / ft <2.000
However,
f21: focal length ft of the 2a-th lens unit: focal length of the entire variable power optical system in the telephoto end state
4. The variable power optical system according to claim 1, wherein the 2a-th lens unit includes a cemented lens. 5.
The variable power optical system according to any one of claims 1 to 4, wherein the 2b lens group is a cemented lens.
The variable power optical system according to any one of claims 1 to 5, wherein the following conditional expression is satisfied.
1.00 <(− fγw) <2.00
However,
fγw: ratio of the amount of movement of the image plane to the amount of movement of the third lens group in the wide-angle end state
The variable power optical system according to any one of claims 1 to 6, wherein the following conditional expression is satisfied.
0.05 <f21 / f22 <3.00
However,
f21: focal length of the 2a-th lens group f22: focal length of the 2b-th lens group
The variable power optical system according to any one of claims 1 to 7, wherein the following conditional expression is satisfied.
0.50 <(− f3) / fw <3.00
However,
f3: focal length of the third lens group fw: focal length of the entire variable power optical system in the wide-angle end state
9. The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
0.100 <G2 / TLt <0.500
However,
G2: Length on the optical axis of the second lens group TLt: Length on the optical axis of the entire variable power optical system in the telephoto end state
The variable power optical system according to any one of claims 1 to 9, wherein the following conditional expression is satisfied.
0.020 <G4 / TLt <0.200
However,
G4: Length on the optical axis of the fourth lens group TLt: Length on the optical axis of the entire variable power optical system in the telephoto end state
The variable-power optical system according to any one of claims 1 to 10, wherein the third lens group includes one lens component and satisfies the following conditional expression.
-20.00 <R2f3 / R1f3 <-1.00
However,
R1f3: radius of curvature of the lens surface closest to the object side of the lens component R2f3: radius of curvature of the lens surface closest to the image side of the lens component
The variable power optical system according to any one of claims 1 to 11, wherein the third lens group has at least one aspheric surface.
The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
−16.00 <(− f23) / ft <5.00
However,
f23: focal length ft of the second lens group c: focal length of the entire variable power optical system in the telephoto end state
14. The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
50.0 ° <2ω <120.0 °
However,
2ω: Full field angle of the variable power optical system in the wide-angle end state
The variable power optical system according to claim 1, wherein the following conditional expression is satisfied.
0.20 <Bfa / fw <0.90
However,
Bfa: air-equivalent back focus of the entire zoom optical system in the wide-angle end state fw: focal length of the entire zoom optical system in the wide-angle end state
An optical apparatus comprising the variable power optical system according to any one of claims 1 to 15.
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power A method of manufacturing a variable power optical system having
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 fourth lens group change. The distance between the lens group is configured to change,
The second lens group includes, in order from the object side, a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power. Configured to
Moving the 2b lens group so as to include a component in a direction perpendicular to the optical axis to correct image blur;
A method of manufacturing a variable power optical system, wherein the third lens group moves in the optical axis direction during focusing.