JP2020177057A - Zoom optical system, optical device, and method of manufacturing zoom optical system - Google Patents

Abstract

To provide a zoom optical system which effectively suppresses aberration variation while zooming, an optical device, and a method of manufacturing the zoom optical system.SOLUTION: A zoom optical system used for optical devices such as cameras is provided, comprising, in order from the object side, a first lens group G1 having positive refractive power, a second lens group G2 having negative refractive power, a third lens group G3 having positive refractive power, a fourth lens group G4 having positive refractive power, and at least one lens group located on the image side of the fourth lens group. While zooming, the first lens group is stationary with respect to an image plane and distances between adjacent lens groups change. An aperture stop S is located on the image side of the fourth lens group. The zoom optical system is configured to satisfy a condition expressed as: 0.70<(-f2)/Δx2<1.50, where f2 represents a focal length of the second lens group, and Δx2 represents a displacement of the second lens group from the wide-angle end to the telephoto end when the movement toward the image side is defined as positive.SELECTED DRAWING: Figure 1

Description

The present invention relates to a variable magnification optical system, an optical instrument, and a method for manufacturing the variable magnification optical system.

Conventionally, variable magnification optical systems suitable for photographic cameras, electronic still cameras, video cameras and the like have been proposed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2016-224180

The variable magnification optical system of the present disclosure includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refraction in order from the object side. It has a fourth lens group having power and at least one lens group located on the image side of the fourth lens group, and the first lens group is fixed to the image plane and adjacent to each other at the time of scaling. The distance between each lens group changes, and an aperture aperture is provided on the image side of the fourth lens group, satisfying the following conditional expression.
(1) 0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance from the wide-angle end state to the telephoto end state of the second lens group when the movement to the image side is positive.

The method for manufacturing the variable magnification optical system of the present disclosure includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. It is a method for manufacturing a variable magnification optical system having a fourth lens group having a positive refractive power and at least one lens group located on the image side of the fourth lens group, and satisfies the following conditional expression (1). The first lens group is fixed to the image plane at the time of scaling, the distance between adjacent lens groups changes, and the aperture aperture is provided on the image side of the fourth lens group. ..
(1) 0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance from the wide-angle end state to the telephoto end state of the second lens group when the movement to the image side is positive.

FIG. 1 is a cross-sectional view of the variable magnification optical system of the first embodiment in the wide-angle end state (W) and the telephoto end state (T). FIG. 2A is a diagram of various aberrations when the variable-magnification optical system of the first embodiment is in focus at the wide-angle end state, and FIG. 2B is an intermediate diagram of the variable-magnification optical system of the first embodiment. FIG. 2C is an aberration diagram at the time of focusing on an infinity object in a focal length state, and FIG. 2C is an aberration diagram at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the first embodiment. FIG. 3 is a cross-sectional view of the variable magnification optical system of the second embodiment in the wide-angle end state (W) and the telephoto end state (T). FIG. 4A is a diagram of various aberrations at the time of focusing on an infinity object in the wide-angle end state of the variable magnification optical system of the second embodiment, and FIG. 4B is an intermediate diagram of the variable magnification optical system of the second embodiment. FIG. 4C is an aberration diagram at the time of focusing on an infinity object in a focal length state, and FIG. 4C is an aberration diagram at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the second embodiment. FIG. 5 is a cross-sectional view of the variable magnification optical system of the third embodiment in the wide-angle end state (W) and the telephoto end state (T). FIG. 6A is a diagram of various aberrations at the time of focusing an object at infinity in the wide-angle end state of the variable magnification optical system of the third embodiment, and FIG. 6B is an intermediate of the variable magnification optical system of the third embodiment. FIG. 6C is an aberration diagram at the time of focusing an infinity object in a focal length state, and FIG. 6C is an aberration diagram at the time of focusing an infinity object in a telephoto end state of the variable magnification optical system of the third embodiment. FIG. 7 is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the wide-angle end state (W) and the telephoto end state (T). FIG. 8A is a diagram of various aberrations at the time of focusing an object at infinity in the wide-angle end state of the variable magnification optical system of the fourth embodiment, and FIG. 8B is an intermediate of the variable magnification optical system of the fourth embodiment. FIG. 8C is a diagram of various aberrations at the time of focusing on an infinity object in a focal length state, and FIG. 8C is a diagram of various aberrations at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the fourth embodiment. FIG. 9 is a cross-sectional view of the variable magnification optical system of the fifth embodiment in the wide-angle end state (W) and the telephoto end state (T). FIG. 10A is a diagram of various aberrations at the time of focusing an object at infinity in the wide-angle end state of the variable magnification optical system of the fifth embodiment, and FIG. 10B is an intermediate of the variable magnification optical system of the fifth embodiment. FIG. 10 (c) is a diagram of various aberrations at the time of focusing on an infinity object in a focal length state, and FIG. 10 (c) is a diagram of various aberrations at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the fifth embodiment. FIG. 11 is a cross-sectional view of the variable magnification optical system of the sixth embodiment in the wide-angle end state (W) and the telephoto end state (T). FIG. 12 (a) is a diagram of various aberrations at the time of focusing on an infinity object in the wide-angle end state of the variable magnification optical system of the sixth embodiment, and FIG. 12 (b) is an intermediate diagram of the variable magnification optical system of the sixth embodiment. FIG. 12 (c) is a diagram of various aberrations when the object is in focus at infinity in the focal length state, and FIG. 12 (c) is a diagram of various aberrations when the object is in focus at infinity in the telephoto end state of the variable magnification optical system of the sixth embodiment. It is a schematic diagram of the camera provided with the variable magnification optical system of this embodiment. It is a flowchart which shows the outline of the manufacturing method of the variable magnification optical system of this embodiment.

Hereinafter, a method for manufacturing the variable magnification optical system, the optical device, and the variable magnification optical system according to the embodiment of the present application will be described.

In the variable magnification optical system of the present embodiment, in order from the object side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, and the positive It has a fourth lens group having an optical power and at least one lens group located on the image side of the fourth lens group. In the variable magnification optical system of the present embodiment, the first lens group is fixed to the image plane at the time of magnification change, the distance between adjacent lens groups changes, and the aperture aperture is closer to the image side than the fourth lens group. And satisfy the following conditional expression.
(1) 0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance of the second lens group from the wide-angle end state to the telephoto end state when the movement toward the image side is positive.

Under such a configuration, the variable magnification optical system of the present embodiment can effectively suppress aberration fluctuations during magnification change.

In the variable magnification optical system of the present embodiment, the ratio of the focal length of the second lens group to the moving distance of the second lens group is made larger than the lower limit in the equation (1), so that the negative of the second lens group is negative. The power can be reduced, and it becomes easier to balance the aberration correction. Further, by setting the lower limit value of the conditional expression (1) to 0.75, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (1) are set to 0.80, 0.85, 0.90, 0.93, 0.95, 0.98, 1. It is preferably 00, 1.03, 1.05, 1.08, and further 1.10.

In the variable magnification optical system of the present embodiment, the moving distance of the second lens group is set by making the ratio of the focal length of the second lens group to the moving distance of the second lens group smaller than the upper limit in the equation (1). Can be made relatively large, and it becomes easier to balance the aberration correction. Further, by setting the upper limit value of the conditional expression (1) to 1.45, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (1) are set to 1.40, 1.35, 1.30, 1.28, 1.25, 1.23, 1. It is preferably 20, 1.18, and further 1.15.

In the variable magnification optical system of the present embodiment, the position of the aperture diaphragm is on the image side of the fourth lens group. With this configuration, the variable magnification optical system of the present embodiment can satisfactorily correct various aberrations including spherical aberration. Further, since the diameter of the luminous flux on the image side is relatively smaller than that of the fourth lens group, the variable magnification optical system of the present embodiment can shorten the opening / closing time of the diaphragm, and as a result, increase the continuous shooting speed. Can be done.

In the variable magnification optical system of the present embodiment, the length of the entire optical system becomes constant at the time of magnification change or focusing by fixing the first lens group, so that the aberration fluctuation at the time of magnification change or focusing is reduced. Can be preferred. Usability is improved in the variable magnification optical system of the present embodiment.

With the above configuration, it is possible to realize an optical system having good optical performance capable of satisfactorily correcting various aberrations.

The variable magnification optical system of the present embodiment preferably satisfies the following conditional expression.
(2) 1.50 <f1 / f3 <3.00
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group

In the variable magnification optical system of the present embodiment, the residual aberration of the third lens group is reduced by making the ratio of the focal length of the first lens group to the moving distance of the third lens group smaller than the upper limit value in the equation (2). Since the components can be easily suppressed, it becomes easier to correct the aberration in the entire range at the time of scaling. Further, by setting the upper limit value of the conditional expression (2) to 2.90, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (2) is set to 2.70, 2.60, 2.55, 2.50, 2.45, 2.40, 2. It is preferably 38, 2.35, and more preferably 2.33.

In the variable magnification optical system of the present embodiment, the residual aberration of the third lens group is increased by making the ratio of the focal length of the first lens group to the moving distance of the third lens group larger than the lower limit in the equation (2). Since the components can be easily suppressed, it becomes easier to correct the aberration on the telephoto side. Further, by setting the lower limit value of the conditional expression (2) to 1.60, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit of the conditional expression (2) is set to 1.70, 1.75, 1.80, 1.85, 1.90, 1.93, 1. It is preferably 95, 1.98, and more preferably 2.00.

In the variable magnification optical system of the present embodiment, it is preferable that at least the fourth lens group moves during focusing. The variable magnification optical system of the present embodiment is preferable because it can reduce fluctuations in various aberrations such as spherical aberration during focusing. Further, the variable magnification optical system of the present embodiment can increase the focusing speed by focusing by moving the relatively lightweight fourth lens group.

The variable magnification optical system of the present embodiment preferably satisfies the following conditional expression.
(3) 2.50 <f1 / (-f2) <4.50
However,
f1: Focal length of the first lens group f2: Focal length of the second lens group

In the variable magnification optical system of the present embodiment, the aberration on the telephoto side can be corrected by making the ratio of the focal length of the first lens group to the focal length of the second lens group larger than the lower limit in the equation (3). It will be easier. Further, by setting the lower limit value of the conditional expression (3) to 2.70, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit of the conditional expression (3) is set to 2.80, 2.90, 3.00, 3.05, 3.10, 3.15, 3. It is preferably 20, 3.25, 3.28, 3.30, and further 3.32.

In the variable magnification optical system of the present embodiment, in the equation (3), the ratio of the focal length of the first lens group to the focal length of the second lens group is made smaller than the upper limit value, so that the aberration fluctuation at the time of scaling is changed. Suppression becomes easier. Further, by setting the upper limit value of the conditional expression (3) to 4.40, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (3) is set to 4.30, 4.20, 4.10, 4.00, 3.90, 3.80, 3. It is preferably 75, 3.70, and more preferably 3.68.

In the variable magnification optical system of the present embodiment, it is preferable that the lens component having a positive refractive index is located on the most object side of the second lens group. The lens component refers to a single lens or a bonded lens. By having such a configuration, the variable magnification optical system of the present embodiment makes it easier to correct chromatic aberration in the entire variable magnification region.

In the variable magnification optical system of the present embodiment, it is preferable that the distance between the lens component having a positive refractive power located closest to the object side of the second lens group and the subsequent lens components satisfies the following conditional expression.
(4) 0.50 <Da21 / Dp21 <2.50
However,
Dp21: Thickness on the optical axis of the first lens component, which is a lens component having a positive refractive force located on the most object side of the second lens group Da21: Located on the image side next to the first lens component. Air spacing on the optical axis with the lens component The lens component refers to a single lens or a bonded lens.

In the chromatic aberration optical system of the present embodiment, the ratio of the thickness of the first lens component on the optical axis to the air spacing on the optical axis of the lens component located on the image side in the equation (4) is set from the lower limit. Increasing the size makes it easier to correct chromatic aberration in the entire variable magnification range. Further, by setting the lower limit value of the conditional expression (4) to 0.60, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (4) are set to 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 0. It is preferably 98, and more preferably 1.00.

In the chromatic aberration optical system of the present embodiment, the ratio of the thickness of the first lens component on the optical axis to the air spacing on the optical axis of the lens component located on the image side in the equation (4) is set from the upper limit. By making it smaller, high magnification can be achieved, and it becomes easier to correct peripheral chromatic aberration on the wide-angle side or axial chromatic aberration on the telephoto side. Further, by setting the upper limit value of the conditional expression (4) to 2.40, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (4) is set to 2.30, 2.20, 2.10, 2.05, 2.00, 1.95, 1. It is preferably 90, 1.85, and more preferably 1.83.

The variable magnification optical system of the present embodiment preferably has two or more lenses having at least a positive refractive power in the second lens group. By having such a configuration, the variable magnification optical system of the present embodiment can more easily balance the chromatic aberration correction in the entire variable magnification region with other aberration corrections.

In the variable magnification optical system of the present embodiment, it is preferable that the first lens, which is a lens having a positive refractive power located closest to the object side of the second lens group, satisfies the following conditional expression.
(5) −0.015 <θgFP1-0.6558 + 0.001982 × νdP1 <−0.000
However,
νdP1: Abbe number of the glass material used for the first lens θg FP1: Partial dispersion ratio of the glass material used for the first lens At this time, the Abbe number νd and the partial dispersion ratio θgF have the refractive index with respect to the C line nC. When the refractive index for the d line is nd, the refractive index for the F line is nF, and the refractive index for the g line is ng, the values are defined by the following equations:
νd = (nd-1) / (nF-nC)
θgF = (ng-nF) / (nF-nC)

The variable magnification optical system of the present embodiment can improve the overall chromatic aberration by satisfying the equation (5). Further, the variable magnification optical system of the present embodiment more easily corrects the lateral chromatic aberration on the wide-angle side and the axial chromatic aberration on the telephoto side by making the Abbe number and the partial dispersion ratio of the first lens smaller than the upper limit values. it can. Further, by setting the lower limit value of the conditional expression (5) to −0.012, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (5) are set to -0.010, -0.008, -0.007, -0.006, and further to -0.005. It is preferable to do so. On the other hand, by setting the upper limit value of the conditional expression (5) to −0.001, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (5) to -0.002 and further to -0.003.

The variable magnification optical system of the present embodiment preferably has a second lens, which is a positive lens that satisfies all of the following conditional expressions, in the second lens group. By having such a configuration, the variable magnification optical system of the present embodiment makes it easier to correct chromatic aberration in the entire variable magnification region.
(6) 18.00 <νdP2 <35.00
(7) 1.83 <ndP2 + (0.01425 × νdP2) <2.15
(8) 0.702 <θgFP2 + (0.00316 × νdP2)
However,
ndP2: Refractive index of the glass material used for the second lens with respect to the d-line ν dP2: Abbe number of the glass material used for the second lens θgFP2: Partial dispersion ratio of the glass material used for the second lens At this time, Abbe The number νd and the partial dispersion ratio θgF are defined by the following equations, where nC is the refractive index for the C line, nd is the refractive index for the d line, nF is the refractive index for the F line, and ng is the refractive index for the g line. Value:
νd = (nd-1) / (nF-nC)
θgF = (ng-nF) / (nF-nC)

The conditional expression (6) defines an appropriate range of the Abbe number of the material of the second lens. By satisfying the conditional equation (6), it is possible to satisfactorily correct reference aberrations such as spherical aberration and coma, and correct primary chromatic aberration. By setting the upper limit value of the conditional expression (6) to 33.00, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (6) to 31.50, 30.00, 28.50, and further 27.00. On the other hand, by setting the lower limit value of the conditional expression (6) to 20.00, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (6) to 21.00, 22.00, 23.00, 24.00, and further 24.40.

The conditional expression (7) defines an appropriate relationship between the refractive index of the material of the second lens and the Abbe number. By satisfying the conditional expression (7), it is possible to satisfactorily correct reference aberrations such as spherical aberration and coma, and correct primary chromatic aberration. By setting the upper limit value of the conditional expression (7) to 2.15, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (7) to 2.13 and further to 2.12. On the other hand, by setting the lower limit value of the conditional expression (7) to 1.85, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit of the conditional expression (7) is set to 1.88, 1.90, 1.92, 1.95, 1.97, 1.99, 2. It is preferably 00, and more preferably 2.02.

The conditional expression (8) appropriately defines the anomalous dispersibility of the material of the second lens. By satisfying the conditional expression (8), in the correction of chromatic aberration, the secondary spectrum can be satisfactorily corrected in addition to the primary chromatic aberration correction. By setting the lower limit value of the conditional expression (8) to 0.704, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, it is preferable to set the lower limit values of the conditional expression (8) to 0.707, 0.710, 0.712, and further 0715.

In the variable magnification optical system of the present embodiment, it is preferable that the third lens group is fixed at the time of magnification change. By having such a configuration, the variable magnification optical system of the present embodiment makes it easier to suppress aberration fluctuations during magnification change.

In the variable magnification optical system of the present embodiment, it is preferable that the lens group on the image side of the fourth lens group has a negative refractive power as a whole in the wide-angle end state. By having such a configuration, the variable magnification optical system of the present embodiment can easily correct the aberration on the telephoto side and more easily correct the curvature of field in the entire variable magnification region.

In the variable magnification optical system of the present embodiment, it is preferable that the focal length of the first lens group and the focal length of the entire lens group located on the image side of the fourth lens group in the wide-angle end state satisfy the following conditional equations.
(9) -3.00 <f1 / (-fRw) <3.00
However,
f1: Focal length of the first lens group fRw: Focal length of the entire lens group located on the image side of the fourth lens group in the wide-angle end state

The variable magnification optical system of the present embodiment defines the ratio between the focal length of the first lens group and the focal length of the entire lens group located on the image side of the fourth lens group in the wide-angle end state in the equation (9). It is a thing. By satisfying the conditional expression (9), it becomes easier to correct curvature of field and distortion in the entire variable magnification region. Further, by setting the upper limit value of the conditional expression (9) to 2.90, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (9) is set to 2.80, 2.70, 2.60, 2.50, 2.40, 2.30, 2. It is preferably 20, 2.10, and more preferably 2.05. On the other hand, by setting the lower limit value of the conditional expression (9) to -2.50, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (9) are set to -2.00, -1.50, -1.00, -0.50, 0.50, 0. It is preferably 80, 1.00, 1.20, and more preferably 1.50.

In the variable magnification optical system of the present embodiment, it is preferable that the second lens group has at least five or more lenses. By having such a configuration, the variable magnification optical system of the present embodiment can more easily correct the aberration.

In the variable magnification optical system of the present embodiment, the aperture diaphragm is preferably located inside the fifth lens group adjacent to the image side with respect to the fourth lens group. By having such a configuration, the variable magnification optical system of the present embodiment can suppress variations in optical performance for each product.

The variable magnification optical system of the present embodiment preferably satisfies the following conditional expression.
(10) 0.05 <β4w <0.70
However,
β4w: Horizontal magnification of the fourth lens group in the wide-angle end state

The variable magnification optical system of the present embodiment can suppress aberration fluctuations during focusing by satisfying the conditional expression (10). Further, by setting the upper limit value of the conditional expression (10) to 0.65, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (10) are set to 0.60, 0.55, 0.50, 0.45, 0.40, 0.35, 0. It is preferably 33, 0.30, and more preferably 0.29. On the other hand, by setting the lower limit value of the conditional expression (10) to 0.08, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (10) are set to 0.10, 0.12, 0.14, 0.15, 0.17, 0.18, and further 0. It is preferably .19.

The variable magnification optical system of the present embodiment preferably satisfies the following conditions.
(11) 0.60 <β4t / β4w <1.30
However,
β4w: Lateral magnification of the fourth lens group in the wide-angle end state β4t: Lateral magnification of the fourth lens group in the telephoto end state

By satisfying the conditional equation (11), the variable magnification optical system of the present embodiment makes it easier to suppress aberration fluctuations during magnification change. Further, by setting the upper limit value of the conditional expression (11) to 1.25, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (11) are set to 1.20, 1.18, 1.15, 1.13, 1.10, 1.08, 1. It is preferably 05 and 1.03. On the other hand, by setting the lower limit value of the conditional expression (11) to 0.63, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (11) are set to 0.65, 0.68, 0.70, 0.73, 0.75, 0.58, 0. It is preferably 80, more preferably 0.83.

In the variable magnification optical system of the present embodiment, all the lens surfaces included in the first lens group, the second lens group, the third lens group, the fourth lens group, and the lens group on the image side of the fourth lens group are spherical. Alternatively, it is preferably flat. By having such a configuration, the variable magnification optical system of the present embodiment facilitates lens processing and assembly adjustment, and can prevent deterioration of optical performance due to an error in lens processing and assembly adjustment.

The optical device of this embodiment has a variable magnification optical system having the above-described configuration. As a result, it is possible to realize an optical device capable of effectively suppressing aberration fluctuations during scaling.

The method for manufacturing the variable magnification optical system of the present embodiment is, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. A method for manufacturing a variable magnification optical system having a fourth lens group having a positive refractive power and at least one lens group located on the image side of the fourth lens group, wherein the following conditional expression (1) is applied. It is configured to be satisfactory, and the first lens group is fixed to the image plane at the time of scaling, the distance between adjacent lens groups changes, and the aperture aperture is provided on the image side of the fourth lens group. To do.
(1) 0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance of the second lens group from the wide-angle end state to the telephoto end state when the movement toward the image side is positive.

By such a method for manufacturing a variable magnification optical system, it is possible to manufacture a variable magnification optical system capable of effectively suppressing aberration fluctuations during magnification change.

(Numerical example)
Hereinafter, examples of the present application will be described with reference to the drawings.

(First Example)
FIG. 1 is a cross-sectional view of the variable magnification optical system of the first embodiment in the wide-angle end state (W) and the telephoto end state (T).

In the variable magnification optical system of this embodiment, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, and the third lens group G3 having a positive refractive power are arranged in this order from the object side. It has a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 located on the image side of the fourth lens group G4.

The first lens group G1 is composed of a junction positive lens of a negative meniscus lens L11 having a convex surface facing the object side and a biconvex positive lens L12, and a plano-convex lens L13 having a convex surface facing the object side, in order from the object side. Become.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a junction negative lens of a biconvex positive lens L22 and a biconcave negative lens L23, and a biconcave shape in order from the object side. It is composed of a junction negative lens of the negative lens L24 and a positive meniscus lens L25 having a convex surface facing the object side, and a negative meniscus lens L26 having a convex surface facing the image side.

The third lens group G3 is composed of a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a biconvex positive lens L34 in order from the object side.

The fourth lens group G4 is composed of a plano-convex lens L41 whose convex surface is directed toward the image side, a biconvex positive lens L42, and a biconcave negative lens L43 in this order from the object side.

The fifth lens group G5 includes a biconcave negative lens L51, an aperture aperture S, a biconvex positive lens L52, a negative meniscus lens L53 with a convex surface facing the object side, and an image side in order from the object side. A positive meniscus lens L54 with a convex surface facing the surface and a negative lens L55 with a biconcave shape, a biconvex positive lens L56, a negative meniscus lens L57 with a convex surface facing the object side, and a biconvex positive lens. It is composed of a positive lens joined with the lens L58 and a negative lens L59 having a biconcave shape.

An image sensor (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I.

Based on the above configuration, in the variable magnification optical system of this embodiment, when the magnification is changed from the wide-angle end state (W) to the telescopic end state (T), the first lens group G1 and the second lens group G2 The distance, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5 change. As described above, the second lens group G2 and the fourth lens group G4 move along the optical axis. Specifically, the second lens group G2 moves to the image side, and the fourth lens group G4 moves to the object side and then moves to the image side. At the time of scaling, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I.

In the variable magnification optical system of this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group to focus from an infinity object to a short-range object.

In the variable magnification optical system of this embodiment, a part of the fifth lens group G5 is a vibration-proof lens group, and the vibration-proof lens group is moved along a predetermined movement direction including a component in a direction orthogonal to the optical axis. By doing so, image plane correction when image blurring occurs, that is, vibration isolation is performed. The anti-vibration lens group may be a lens group other than the fifth lens group G5, for example, a lens group included in the third lens group.

Table 1 below lists the specifications of the variable magnification optical system of this embodiment. In Table 1, F is the focal length, F.NO is the F number, 2ω is the angle of view (unit is "°"), TL is the total length of the variable magnification optical system, and BF is the back focus, that is, the lens surface on the image side. The distance on the optical axis from the image plane I, Y indicates the image height.

In [Lens Specifications], m is the order of the optical planes counted from the object side, R is the radius of curvature, d is the plane spacing, nd is the refractive index for the d line (wavelength 587.6 nm), and νd is the Abbe number for the d line. θgF indicates the partial dispersion ratio. Here, νd and θgF are defined as nC for the refractive index for the C line (wavelength 656.3 nm), nF for the F line (wavelength 486.1 nm), and ng for the refractive index for the g line (wavelength 435.8 nm). Each is defined by the following equation.
νd = (nd-1) / (nF-nC)
θgF = (ng-nF) / (nF-nC)
In [Lens Specifications], the radius of curvature R = ∞ indicates a plane.

In the [conditional expression corresponding value], f2 is the focal length of the second lens group G2, and Δx2 is the movement distance of the second lens group G2 from the wide-angle end state to the telephoto end state when the movement toward the image side is positive. Is. Further, f1 is the focal length of the first lens group G1 and f3 is the focal length of the third lens group G3. Further, Dp21 is the thickness of the first lens component, which is a lens component having a positive refractive power located on the most object side of the second lens group G2, on the optical axis, and Da21 is the first lens component and the image next to it. It is the air distance on the optical axis with the lens component located on the side. Further, νdP1 is the Abbe number (νd) of the glass material used in the first lens, which is a lens having a positive refractive power located on the most object side of the second lens group, and θgFP1 is used in the first lens. It is the partial dispersion ratio (θgF) of the glass material. Further, ndP2 is the refractive index (nd) of the glass material used for the second lens, which is a positive lens included in the second lens group G2, with respect to the d-line, and νdP2 is the Abbe number of the glass material used for the second lens. It is a number (νd), and θgFP2 is a partial dispersion ratio (θgF) of the glass material used in the second lens. Further, fRw is the focal length of the entire lens group located on the image side of the fourth lens group G4 in the wide-angle end state, β4w is the lateral magnification of the fourth lens group G4 in the wide-angle end state, and β4t is the telephoto end state. It is the lateral magnification of the 4th lens group G4 in. The lens component refers to a single lens or a bonded lens.

Here, the unit of the focal length F, the radius of curvature R and other lengths shown in Table 1 is “mm”. However, the optical system is not limited to this because the same optical performance can be obtained even if the optical system is proportionally expanded or decreased.

The reference numerals in Table 1 described above are also used in the tables of other examples described later.

In this embodiment, the positive meniscus lens L21 corresponds to the first lens, and the positive meniscus lens L25 corresponds to the second lens.

(Table 1)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
F 123.600 200.000 291.000
F.NO 2.91 2.91 2.91
2ω 19.57 12.08 8.29
TL 341.224 341.224 341.223
BF 54.819 54.819 54.819
Y 21.63 21.63 21.63

[Lens specifications]
m R d nd ν d θ gF
Paraboloid ∞ ∞
1 321.66940 5.200 1.902650 35.77
2 151.60700 13.400 1.497820 82.57
3 -748.49330 0.100 1.000000
4 135.41060 13.200 1.433843 95.27
5 ∞ D1 1.000000
6 124.35940 7.600 1.720467 34.71 0.583
7 1981.86680 12.972 1.000000
8 275.61570 4.700 1.717360 29.53
9 -275.46000 2.850 1.696800 55.52
10 109.09020 3.124 1.000000
11 -1986.35680 2.650 1.804000 46.60
12 57.14000 3.700 1.755750 24.71 0.629
13 86.06040 6.757 1.000000
14 -84.28650 2.500 1.870705 40.73
15 -651.88180 D2 1.000000
16 605.01830 4.700 1.755000 52.34
17 -156.13670 0.100 1.000000
18 88.37420 6.800 1.433843 95.27
19 -277.56450 1.626 1.000000
20 -115.63160 4.700 1.654130 39.72
21 88.64080 1.061 1.000000
22 123.70960 5.300 1.910820 35.25
23 -404.22320 D3 1.000000
24 ∞ 4.000 1.804000 46.60
25 -118.33570 0.100 1.000000
26 63.02260 6.800 1.593490 67.00
27 -199.13800 1.800 1.846660 23.82
28 199.01100 D4 1.000000
29 -145.61410 1.900 2.001000 29.12
30 91.09030 5.002 1.000000
31 ∞ 8.000 1.000000 Aperture
32 375.14680 5.000 1.729160 54.61
33 -83.79560 3.919 1.000000
34 368.09220 2.000 1.870705 40.73
35 93.47140 2.746 1.000000
36 -148.92880 3.600 1.805180 25.41
37 -54.33700 1.900 1.516800 64.14
38 107.77010 5.617 1.000000
39 ∞ 8.829 1.000000
40 79.60900 4.400 2.001000 29.12
41 -1873.43360 0.782 1.000000
42 64.03540 3.000 1.804000 46.60
43 33.60900 10.000 1.487490 70.31
44 -77.35390 6.728 1.000000
45 -70.85350 2.000 1.900430 37.38
46 224.49500 BF 1.000000

[Variable interval data at variable magnification]
Wide-angle end state Intermediate focal length state Telephoto end state
D1 5.114 39.909 66.471
D2 62.916 28.122 1.560
D3 21.244 17.600 18.669
D4 5.968 9.611 8.542

[Each group focal length data]
Focal length
1 1 250.635
2 6 -69.674
3 16 108.979
4 24 89.868
5 29 -145.810

[Conditional expression correspondence value]
(1) (-f2) /Δx2= 1.14
(2) f1 / f3 = 2.30
(3) f1 / (-f2) = 3.60
(4) Da21 / Dp21 = 1.71
(5) θgFP1-0.6558 + 0.001982 × νdP1 = -0.004
(6) νdP2 = 24.71
(7) ndP2 + (0.01425 × νdP2) = 2.11
(8) θgFP2 + (0.00316 × νdP2) = 0.71
(9) f1 / (-fRw) = 1.72
(10) β4w = 0.26
(11) β4t / β4w = 0.89

FIG. 2A is a diagram of various aberrations when the variable-magnification optical system of the first embodiment is in focus at the wide-angle end state, and FIG. 2B is an intermediate diagram of the variable-magnification optical system of the first embodiment. FIG. 2C is an aberration diagram at the time of focusing on an infinity object in a focal length state, and FIG. 2C is an aberration diagram at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the first embodiment.

In each aberration diagram, FNO indicates F number and Y indicates image height. In detail, the spherical aberration diagram shows the value of the F number corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height value, and the coma aberration diagram shows the value of each image height. d indicates the d line and g indicates the g line. In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. In the various aberration diagrams of other examples described later, the same reference numerals as those of the various aberration diagrams of this embodiment are used.

From each aberration diagram, it can be seen that the variable magnification optical system of this embodiment effectively suppresses aberration fluctuations during magnification change and has high optical performance.

(Second Example)
FIG. 5 is a cross-sectional view of the variable magnification optical system of the second embodiment in the wide-angle end state (W) and the telephoto end state (T).

In the variable magnification optical system of this embodiment, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, and the third lens group G3 having a positive refractive power are arranged in this order from the object side. It has a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 located on the image side of the fourth lens group G4.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a bonded positive lens L12 having a biconvex positive lens L12, and a biconvex positive lens L13 in order from the object side.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a junction negative lens of a biconvex positive lens L22 and a biconcave negative lens L23, and a biconcave shape in order from the object side. It is composed of a junction negative lens of the negative lens L24 and a positive meniscus lens L25 having a convex surface facing the object side, and a negative meniscus lens L26 having a convex surface facing the image side.

The third lens group G3 includes a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a positive meniscus lens L34 with a convex surface facing the object side, in order from the object side. It consists of.

The fourth lens group G4 is composed of a biconvex positive lens L41, a biconvex positive lens L42, and a biconcave negative lens L43 in this order from the object side.

The fifth lens group G5 includes a biconcave negative lens L51, an aperture aperture S, a biconcave negative lens L52, and a biconvex positive lens L53 in this order from the object side. A junction negative lens of a positive lens L54 with a shape and a negative lens L55 with a biconcave shape, a negative meniscus lens L56 with a convex surface facing the image side, a positive lens L57 with a biconvex shape, and a positive lens L58 with a biconvex shape. It is composed of a bonded positive lens with a negative meniscus lens L59 having a convex surface facing the image side, a positive meniscus lens L510 having a convex surface facing the object side, and a negative lens L511 having a biconcave shape.

An image sensor (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I.

Based on the above configuration, in the variable magnification optical system of this embodiment, when the magnification is changed from the wide-angle end state (W) to the telescopic end state (T), the first lens group G1 and the second lens group G2 The distance, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5 change. As described above, the second lens group G2 and the fourth lens group G4 move along the optical axis. Specifically, the second lens group G2 moves to the image side, and the fourth lens group G4 moves to the object side and then moves to the image side. At the time of scaling, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I.

In the variable magnification optical system of this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group to focus from an infinity object to a short-range object.

In the variable magnification optical system of this embodiment, a part of the fifth lens group G5 is a vibration-proof lens group, and the vibration-proof lens group is moved along a predetermined movement direction including a component in a direction orthogonal to the optical axis. By doing so, image plane correction when image blurring occurs, that is, vibration isolation is performed. The anti-vibration lens group may be a lens group other than the fifth lens group G5, for example, a lens group included in the third lens group.

In this embodiment, the positive meniscus lens L21 corresponds to the first lens, and the positive meniscus lens L25 corresponds to the second lens.

Table 2 below lists the specifications of the variable magnification optical system of this embodiment.

(Table 2)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
F 123.600 200.000 291.000
F.NO 2.91 2.91 2.91
2ω 19.59 12.08 8.29
TL 342.319 342.319 342.319
BF 54.819 54.819 54.819
Y 21.63 21.63 21.63

[Lens specifications]
m R d nd ν d θ gF
Paraboloid ∞ ∞
1 305.70850 4.500 1.902650 35.77
2 148.27732 13.400 1.497820 82.57
3 -804.51207 0.100 1.000000
4 135.34256 12.200 1.433848 95.23
5 -7108.11410 D1 1.000000
6 133.36700 7.100 1.720467 34.71 0.583
7 1705.96720 12.866 1.000000
8 372.24596 4.553 1.755200 27.57
9 -232.89074 2.500 1.651600 58.57
10 105.24684 3.710 1.000000
11 -489.43157 2.500 1.870705 40.73
12 56.38071 4.783 1.749714 24.66 0.627
13 113.72234 5.653 1.000000
14 -90.97294 2.500 1.870705 40.73
15 -442.80561 D2 1.000000
16 225.30614 5.000 1.729160 54.61
17 -166.98906 0.100 1.000000
18 96.48460 7.500 1.433848 95.23
19 -179.59003 1.008 1.000000
20 -116.94301 3.000 1.647690 33.72
21 87.64642 1.294 1.000000
22 134.28076 5.500 2.001003 29.13
23 3791.16980 D3 1.000000
24 1492.74590 4.200 1.804000 46.60
25 -119.96401 0.100 1.000000
26 61.73669 6.900 1.593493 67.00
27 -226.87444 2.200 1.854779 24.80
28 173.88577 D4 1.000000
29 -103.97897 1.800 1.910822 35.25
30 91.72480 4.895 1.000000
31 ∞ 7.753 1.000000 Aperture
32 -6000.75320 1.800 1.903660 31.27
33 105.52585 5.800 1.749500 35.25
34 -64.83775 4.000 1.000000
35 166.45825 4.500 1.850000 27.03
36 -124.25639 1.800 1.517420 52.20
37 46.20206 4.486 1.000000
38 -121.67391 1.800 1.834000 37.18
39 -16783.25800 4.000 1.000000
40 ∞ 7.007 1.000000
41 84.14382 7.000 1.700000 48.10
42 -65.74451 0.100 1.000000
43 971.48692 7.245 1.603420 38.03
44 -51.92908 2.000 1.900433 37.37
45 -922.69980 0.100 1.000000
46 74.76608 6.396 1.729160 54.61
47 133.02260 2.652 1.000000
48 -93.65985 2.000 1.870705 40.73
49 237.45972 BF 1.000000

[Variable interval data at variable magnification]
Wide-angle end state Intermediate focal length state Telephoto end state
D1 7.000 41.385 67.760
D2 62.760 28.374 2.000
D3 20.958 17.381 18.700
D4 6.482 10.059 8.739

[Each group focal length data]
Focal length
1 1 244.561
2 6 -68.997
3 16 111.088
4 24 88.456
5 29 -146.620

[Conditional expression correspondence value]
(1) (-f2) /Δx2= 1.14
(2) f1 / f3 = 2.20
(3) f1 / (-f2) = 3.54
(4) Da21 / Dp21 = 1.81
(5) θgFP1-0.6558 + 0.001982 × νdP1 = -0.004
(6) νdP2 = 24.66
(7) ndP2 + (0.01425 × νdP2) = 2.10
(8) θgFP2 + (0.00316 × νdP2) = 0.71
(9) f1 / (-fRw) = 1.67
(10) β4w = 0.24
(11) β4t / β4w = 0.89

FIG. 4A is a diagram of various aberrations at the time of focusing on an infinity object in the wide-angle end state of the variable magnification optical system of the second embodiment, and FIG. 4B is an intermediate diagram of the variable magnification optical system of the second embodiment. FIG. 4C is an aberration diagram at the time of focusing on an infinity object in a focal length state, and FIG. 4C is an aberration diagram at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the second embodiment.

From each aberration diagram, it can be seen that the variable magnification optical system of this embodiment effectively suppresses aberration fluctuations during magnification change and has high optical performance.

(Third Example)
FIG. 5 is a cross-sectional view of the variable magnification optical system of the third embodiment in the wide-angle end state (W) and the telephoto end state (T).

In the variable magnification optical system of this embodiment, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, and the third lens group G3 having a positive refractive power are arranged in this order from the object side. It has a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 located on the image side of the fourth lens group G4.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a bonded positive lens L12 having a biconvex positive lens L12, and a biconvex positive lens L13 in order from the object side.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a junction negative lens of a biconvex positive lens L22 and a biconcave negative lens L23, and a biconcave shape in order from the object side. It is composed of a junction negative lens of the negative lens L24 and a positive meniscus lens L25 having a convex surface facing the object side, and a negative meniscus lens L26 having a convex surface facing the image side.

The third lens group G3 is composed of a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a biconvex positive lens L34 in order from the object side.

The fourth lens group G4 is composed of a biconvex positive lens L41, a biconvex positive lens L42, and a biconcave negative lens L43 in this order from the object side.

The fifth lens group G5 includes a biconcave negative lens L51, an aperture aperture S, a biconvex positive lens L52, a negative meniscus lens L53 with a convex surface facing the object side, and an image side in order from the object side. A combination of a positive meniscus lens L54 with a convex surface facing the surface and a biconcave negative lens L55, a biconvex positive lens L56, a biconvex positive lens L57, and a biconcave negative lens L58. It is composed of a bonded positive lens, a biconcave negative lens L59, and a positive meniscus lens L510 with a convex surface facing the object side.

An image sensor (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I.

Based on the above configuration, in the variable magnification optical system of this embodiment, when the magnification is changed from the wide-angle end state (W) to the telescopic end state (T), the first lens group G1 and the second lens group G2 The distance, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5 change. As described above, the second lens group G2 and the fourth lens group G4 move along the optical axis. Specifically, the second lens group G2 moves to the image side, and the fourth lens group G4 moves to the object side and then moves to the image side. At the time of scaling, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I.

In the variable magnification optical system of this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group to focus from an infinity object to a short-range object.

In the variable magnification optical system of this embodiment, a part of the fifth lens group G5 is a vibration-proof lens group, and the vibration-proof lens group is moved along a predetermined movement direction including a component in a direction orthogonal to the optical axis. By doing so, image plane correction when image blurring occurs, that is, vibration isolation is performed. The anti-vibration lens group may be a lens group other than the fifth lens group G5, for example, a lens group included in the third lens group.

In this embodiment, the positive meniscus lens L21 corresponds to the first lens, and the positive meniscus lens L25 corresponds to the second lens.

Table 3 below lists the specifications of the variable magnification optical system of this embodiment.

(Table 3)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
F 123.600 200.000 291.000
F.NO 2.91 2.91 2.91
2ω 19.60 12.08 8.29
TL 342.319 342.319 342.319
BF 54.819 54.819 54.819
Y 21.63 21.63 21.63

[Lens specifications]
m R d nd ν d θ gF
Paraboloid ∞ ∞
1 302.77200 4.500 1.902650 35.77
2 151.06890 13.400 1.497820 82.57
3 -959.84270 0.100 1.000000
4 143.16270 13.200 1.433848 95.23
5 -3025.24950 D1 1.000000
6 128.81680 7.100 1.720467 34.71 0.583
7 3656.94160 10.844 1.000000
8 292.00270 4.919 1.717360 29.57
9 -221.46280 2.500 1.696800 55.52
10 107.23890 3.640 1.000000
11 -520.59530 2.500 1.870705 40.73
12 60.73180 4.526 1.749714 24.66 0.627
13 119.16390 5.399 1.000000
14 -97.72110 2.500 1.870705 40.73
15 -542.32470 D2 1.000000
16 223.98030 5.000 1.755000 52.33
17 -176.54290 0.100 1.000000
18 94.53500 6.800 1.433848 95.23
19 -600.57610 2.167 1.000000
20 -116.42870 3.000 1.654115 39.68
21 92.72900 0.987 1.000000
22 127.94710 4.500 1.903660 31.27
23 -609.03030 D3 1.000000
24 958.30960 4.200 1.804000 46.60
25 -127.34340 0.100 1.000000
26 66.46510 6.700 1.593493 67.00
27 -162.84250 2.000 1.846663 23.78
28 205.44410 D4 1.000000
29 -157.20240 1.800 2.001003 29.13
30 79.78420 5.151 1.000000
31 ∞ 9.376 1.000000 Aperture
32 843.57770 5.000 1.804000 46.60
33 -84.06670 4.000 1.000000
34 288.71080 2.000 1.806099 33.27
35 95.09840 3.190 1.000000
36 -116.99270 4.300 1.850000 27.03
37 -52.44810 1.800 1.487490 70.32
38 86.48950 5.000 1.000000
39 ∞ 5.500 1.000000
40 62.82990 7.200 1.654115 39.68
41 -92.86850 2.862 1.000000
42 61.33920 5.700 1.497820 82.57
43 -672.99910 2.000 1.850000 27.03
44 282.24280 5.879 1.000000
45 -97.82820 2.000 1.900433 37.37
46 42.47710 0.433 1.000000
47 46.32540 4.200 1.795040 28.69
48 297.57420 BF 1.000000

[Variable interval data at variable magnification]
Wide-angle end state Intermediate focal length state Telephoto end state
D1 7.000 43.978 72.729
D2 67.879 30.901 2.150
D3 18.700 16.048 18.700
D4 5.850 8.502 5.850

[Each group focal length data]
Focal length
1 1 251.828
2 6 -74.466
3 16 110.738
4 24 92.308
5 29 -146.969

[Conditional expression correspondence value]
(1) (-f2) /Δx2= 1.13
(2) f1 / f3 = 2.27
(3) f1 / (-f2) = 3.38
(4) Da21 / Dp21 = 1.53
(5) θgFP1-0.6558 + 0.001982 × νdP1 = -0.004
(6) νdP2 = 24.66
(7) ndP2 + (0.01425 × νdP2) = 2.10
(8) θgFP2 + (0.00316 × νdP2) = 0.71
(9) f1 / (-fRw) = 1.71
(10) β4w = 0.28
(11) β4t / β4w = 1.00

FIG. 6A is a diagram of various aberrations at the time of focusing an object at infinity in the wide-angle end state of the variable magnification optical system of the third embodiment, and FIG. 6B is an intermediate of the variable magnification optical system of the third embodiment. FIG. 6C is an aberration diagram at the time of focusing an infinity object in a focal length state, and FIG. 6C is an aberration diagram at the time of focusing an infinity object in a telephoto end state of the variable magnification optical system of the third embodiment.

From each aberration diagram, it can be seen that the variable magnification optical system of this embodiment effectively suppresses aberration fluctuations during magnification change and has high optical performance.

(Fourth Example)
FIG. 7 is a cross-sectional view of the variable magnification optical system of the fourth embodiment in the wide-angle end state and the telephoto end state.

In the variable magnification optical system of this embodiment, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, and the third lens group G3 having a positive refractive power are arranged in this order from the object side. It has a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 located on the image side of the fourth lens group G4.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a biconvex shape, and a positive meniscus lens L13 having a convex surface facing the object side, in order from the object side. Consists of.

The second lens group G2 includes a positive meniscus lens L21 having a convex surface facing the object side, a negative meniscus lens L22 having a convex surface facing the object side, a biconcave negative lens L23, and a convex surface toward the object side in order from the object side. It is composed of a negative meniscus lens L24 with a positive meniscus lens L24 facing the image side and a negative meniscus lens L25 with a convex surface facing the image side.

The third lens group G3 is composed of a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a biconvex positive lens L34 in order from the object side.

The fourth lens group G4 is composed of a biconvex positive lens L41, a biconvex positive lens L42, and a biconcave negative lens L43 in this order from the object side.

The fifth lens group G5 includes an aperture aperture S, a negative meniscus lens L51 with a convex surface facing the object side, a positive meniscus lens L52 with a convex surface facing the image side, and a negative lens L52 with a convex surface facing the image side, in order from the object side. A junction positive lens with a meniscus lens L53, a junction negative lens with a biconvex positive lens L54 and a biconcave negative lens L55, a plano-concave lens L56 with a concave surface facing the object side, and a biconvex positive lens. It is composed of a junction positive lens of L57, a biconvex positive lens L58 and a negative meniscus lens L59 with a convex surface facing the image side, a biconvex positive lens L510, and a biconcave negative lens L511.

An image sensor (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I.

Based on the above configuration, in the variable magnification optical system of this embodiment, when the magnification is changed from the wide-angle end state (W) to the telescopic end state (T), the first lens group G1 and the second lens group G2 The distance, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5 change. As described above, the second lens group G2 and the fourth lens group G4 move along the optical axis. Specifically, the second lens group G2 moves to the image side, and the fourth lens group G4 moves to the object side and then moves to the image side. At the time of scaling, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I.

In the variable magnification optical system of this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group to focus from an infinity object to a short-range object.

In the variable magnification optical system of this embodiment, a part of the fifth lens group G5 is a vibration-proof lens group, and the vibration-proof lens group is moved along a predetermined movement direction including a component in a direction orthogonal to the optical axis. By doing so, image plane correction when image blurring occurs, that is, vibration isolation is performed. The anti-vibration lens group may be a lens group other than the fifth lens group G5, for example, a lens group included in the third lens group.

In this embodiment, the positive meniscus lens L24 corresponds to the second lens.

Table 4 below lists the specifications of the variable magnification optical system of this embodiment.

(Table 4)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
F 123.600 200.000 291.000
F.NO 2.91 2.91 2.91
2ω 19.61 12.08 8.29
TL 338.316 338.316 338.316
BF 54.819 54.819 54.819
Y 21.63 21.63 21.63

[Lens specifications]
m R d nd ν d θ gF
Paraboloid ∞ ∞
1 348.71610 4.500 1.850260 32.35
2 170.05400 13.400 1.497820 82.57
3 -755.90590 0.100 1.000000
4 155.47150 12.200 1.433848 95.23
5 19149.78900 D1 1.000000
6 93.28940 8.600 1.795040 28.69
7 831.89690 9.062 1.000000
8 202.64280 2.500 1.743200 49.26
9 80.24330 4.488 1.000000
10 -934.36020 2.500 1.864070 39.49
11 52.17670 5.500 1.659398 26.87 0.633
12 123.75500 5.469 1.000000
13 -92.40290 2.500 1.881003 40.14
14 -433.74880 D2 1.000000
15 240.39350 5.000 1.804000 46.60
16 -227.45800 0.100 1.000000
17 94.59170 7.500 1.433848 95.23
18 -256.83990 1.829 1.000000
19 -104.42840 3.000 1.620040 36.40
20 86.84160 1.276 1.000000
21 130.70040 5.500 1.886339 40.15
22 -1186.34760 D3 1.000000
23 495.28740 4.000 1.795000 45.31
24-115.44490 0.200 1.000000
25 54.17880 7.300 1.487490 70.32
26 -275.91900 2.200 1.854779 24.80
27 187.43400 D4 1.000000
28 ∞ 3.800 1.000000 Aperture
29 12538.01000 1.800 2.001000 29.12
30 75.76220 3.224 1.000000
31 -81.87080 2.000 1.846663 23.78
32 -72.65200 5.800 1.593190 67.90
33 -73.14180 4.000 1.000000
34 1720.37300 4.500 1.903660 31.27
35 -92.92650 1.800 1.517420 52.20
36 53.42910 3.622 1.000000
37 -133.88100 1.800 1.766840 46.78
38 ∞ 4.000 1.000000
39 ∞ 4.860 1.000000
40 201.91010 4.000 1.744000 44.80
41 -316.45680 0.100 1.000000
42 148.64770 7.400 1.667550 41.87
43 -54.69010 2.000 1.881003 40.14
44 -179.56290 0.100 1.000000
45 108.03460 9.000 1.647690 33.72
46 -73.57780 5.040 1.000000
47 -70.73100 2.000 1.900433 37.37
48 237.45970 BF 1.000000

[Variable interval data at variable magnification]
Wide-angle end state Intermediate focal length state Telephoto end state
D1 7.146 46.306 76.646
D2 71.580 32.420 2.080
D3 19.659 17.178 19.183
D4 5.541 8.022 6.017

[Each group focal length data]
Focal length
1 1 265.040
2 6 -78.766
3 15 126.666
4 23 82.318
5 28 -131.341

[Conditional expression correspondence value]
(1) (-f2) /Δx2= 1.13
(2) f1 / f3 = 2.09
(3) f1 / (-f2) = 3.36
(4) Da21 / Dp21 = 1.05
(6) νdP2 = 26.87
(7) ndP2 + (0.01425 × νdP2) = 2.04
(8) θgFP2 + (0.00316 × νdP2) = 0.72
(9) f1 / (-fRw) = 2.02
(10) β4w = 0.20
(11) β4t / β4w = 0.97

FIG. 8A is a diagram of various aberrations at the time of focusing an object at infinity in the wide-angle end state of the variable magnification optical system of the fourth embodiment, and FIG. 8B is an intermediate of the variable magnification optical system of the fourth embodiment. FIG. 8C is a diagram of various aberrations at the time of focusing on an infinity object in a focal length state, and FIG. 8C is a diagram of various aberrations at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the fourth embodiment.

From each aberration diagram, it can be seen that the variable magnification optical system of this embodiment effectively suppresses aberration fluctuations during magnification change and has high optical performance.

(Fifth Example)
FIG. 9 is a cross-sectional view of the variable magnification optical system of the fifth embodiment in the wide-angle end state (W) and the telephoto end state (T).

In the variable magnification optical system of this embodiment, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, and the third lens group G3 having a positive refractive power are arranged in this order from the object side. It has a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 located on the image side of the fourth lens group G4.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a biconvex positive lens L12, and a positive meniscus lens L13 having a convex surface facing the object side in order from the object side.

The second lens group G2 includes a positive junction lens L21 having a biconvex positive lens L21 and a negative lens L22 having a biconcave shape, a negative meniscus lens L23 having a convex surface facing the object side, and a convex surface toward the object side in order from the object side. It is composed of a junction negative lens with a positive meniscus lens L24, a biconcave negative lens L25, and a biconcave negative lens L26.

The third lens group G3 is composed of a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a biconvex positive lens L34 in order from the object side.

The fourth lens group G4 is composed of a biconvex positive lens L41, a biconvex positive lens L42, and a biconcave negative lens L43 in this order from the object side.

The fifth lens group G5 includes an aperture aperture S, a negative meniscus lens L51 having a convex surface facing the object side, and a positive meniscus lens lens L52 having a convex surface facing the object side, in order from the object side. Negative meniscus lens L53 with a convex surface, a negative lens L54 with a biconcave shape and a positive lens L55 with a biconvex shape, a biconvex positive lens L56, and a biconvex positive lens L57. It is composed of a positive meniscus lens L58 having a convex surface facing the image side and a negative meniscus lens L59 having a convex surface facing the image side.

An image sensor (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I.

Based on the above configuration, in the variable magnification optical system of this embodiment, when the magnification is changed from the wide-angle end state (W) to the telescopic end state (T), the first lens group G1 and the second lens group G2 The distance, the distance between the second lens group G2 and the third lens group G3, the distance between the third lens group G3 and the fourth lens group G4, and the distance between the fourth lens group G4 and the fifth lens group G5 change. As described above, the second lens group G2 and the fourth lens group G4 move along the optical axis. Specifically, the second lens group G2 moves to the image side, and the fourth lens group G4 moves to the object side and then moves to the image side. At the time of scaling, the first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I.

In the variable magnification optical system of this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group to focus from an infinity object to a short-range object.

In the variable magnification optical system of this embodiment, a part of the fifth lens group G5 is a vibration-proof lens group, and the vibration-proof lens group is moved along a predetermined movement direction including a component in a direction orthogonal to the optical axis. By doing so, image plane correction when image blurring occurs, that is, vibration isolation is performed. The anti-vibration lens group may be a lens group other than the fifth lens group G5, for example, a lens group included in the third lens group.

Table 5 below lists the specifications of the variable magnification optical system of this embodiment.

(Table 5)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
F 123.001 200.100 293.996
F.NO 2.90 2.90 2.90
2ω 19.73 12.12 8.24
TL 342.318 342.316 342.313
BF 54.818 54.816 54.813
Y 21.63 21.63 21.63

[Lens specifications]
m R d nd ν d θ gF
Paraboloid ∞ ∞
1 335.53310 3.000 1.834000 37.18
2 154.51120 0.400 1.000000
3 154.29310 13.408 1.433852 95.25
4 -520.83390 0.100 1.000000
5 135.36400 12.165 1.433852 95.25
6 3736.13210 D1 1.000000
7 128.29510 8.500 1.795040 28.69
8-4223.17520 2.200 1.487490 70.31
9 984.97450 12.613 1.000000
10 500.00000 2.400 1.719990 50.27
11 49.36080 5.000 1.567320 42.58
12 99.14650 7.500 1.000000
13 -335.01310 2.500 1.729160 54.61
14 226.43530 5.000 1.000000
15 -100.11080 2.000 1.816000 46.59
16 1196.71850 D2 1.000000
17 168.73530 4.500 1.902650 35.73
18 -506.91230 0.200 1.000000
19 102.86130 5.400 1.487490 70.31
20 -507.75180 2.500 1.000000
21 -106.64850 5.400 1.723420 38.03
22 94.05710 0.909 1.000000
23 120.03180 6.000 1.677900 55.35
24-176.78630 D3 1.000000
25 2377.31100 3.921 1.806100 40.97
26 -102.85300 0.200 1.000000
27 49.64850 7.300 1.497820 82.57
28 -223.63440 2.100 2.001000 29.12
29 201.12050 D4 1.000000
30 ∞ 3.700 1.000000 Aperture
31 320.33010 2.000 1.950000 29.37
32 35.01770 5.000 1.757000 47.86
33 104.49890 2.984 1.000000
34 206.07800 2.800 1.903660 31.27
35 56.03080 3.678 1.000000
36 -112.22280 2.729 1.664460 35.87
37 42.39010 6.500 1.805180 25.45
38 -375.28100 10.000 1.000000
39 192.85190 5.500 1.664460 35.87
40 -194.03960 1.415 1.000000
41 158.67080 4.000 2.000690 25.46
42 -324.20510 6.000 1.000000
43 -176.56360 4.700 1.638540 55.34
44 -62.98620 5.495 1.000000
45 -55.01520 4.000 1.762000 40.11
46 -1000.00000 BF 1.000000

[Variable interval data at variable magnification]
Wide-angle end state Intermediate focal length state Telephoto end state
D1 5.500 43.477 73.389
D2 70.889 32.912 3.000
D3 20.819 18.247 20.819
D4 4.576 7.147 4.576

[Each group focal length data]
Focal length
1 1 261.034
2 7 -75.497
3 17 124.411
4 25 85.556
5 30 -157.283

[Conditional expression correspondence value]
(1) (-f2) /Δx2=1.11
(2) f1 / f3 = 2.10
(3) f1 / (-f2) = 3.46
(4) Da21 / Dp21 = 1.18
(9) f1 / (-fRw) = 1.66
(10) β4w = 0.21
(11) β4t / β4w = 1.00

FIG. 10A is a diagram of various aberrations at the time of focusing an object at infinity in the wide-angle end state of the variable magnification optical system of the fifth embodiment, and FIG. 10B is an intermediate of the variable magnification optical system of the fifth embodiment. FIG. 10 (c) is a diagram of various aberrations at the time of focusing on an infinity object in a focal length state, and FIG. 10C is a diagram of various aberrations at the time of focusing on an infinity object in the telephoto end state of the variable magnification optical system of the fifth embodiment.

From each aberration diagram, it can be seen that the variable magnification optical system of this embodiment effectively suppresses aberration fluctuations during magnification change and has high optical performance.

(6th Example)
FIG. 11 is a cross-sectional view of the variable magnification optical system of the sixth embodiment in the wide-angle end state (W) and the telephoto end state (T).

In the variable magnification optical system of this embodiment, the first lens group G1 having a positive refractive power, the second lens group G2 having a negative refractive power, and the third lens group G3 having a positive refractive power are arranged in this order from the object side. It has a fourth lens group G4 having a positive refractive power, and a fifth lens group G5, a sixth lens group G6, and a seventh lens group G7 located on the image side of the fourth lens group G4.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a biconvex shape, and a positive meniscus lens L13 having a convex surface facing the object side, in order from the object side. Consists of.

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 negative meniscus lens L23 having a convex surface facing the object side in order from the object side. It is composed of a junction negative lens, a junction negative lens L24 having a biconcave shape, a positive meniscus lens L25 having a convex surface facing the object side, and a negative meniscus lens L26 having a convex surface facing the image side.

The third lens group G3 is composed of a biconvex positive lens L31, a biconvex positive lens L32, a biconcave negative lens L33, and a biconvex positive lens L34 in order from the object side.

The fourth lens group G4 is composed of a plano-convex lens L41 whose convex surface is directed toward the image side, a biconvex positive lens L42, and a biconcave negative lens L43 in this order from the object side.

The fifth lens group G5 includes a biconcave negative lens L51, an aperture diaphragm S, a plano-concave lens L52 with a concave surface facing the image side, and a biconvex positive lens L53 in order from the object side. Consists of.

The sixth lens group G6 includes a negative meniscus lens L61 having a convex surface facing the object side, a positive meniscus lens L62 having a convex surface facing the image side, and a negative lens L63 having a biconcave shape in order from the object side. Consists of.

The seventh lens group G7 includes a biconvex positive lens L71, a negative meniscus lens L72 with a convex surface facing the object side, a biconvex positive lens L73, and a biconcave positive lens in order from the object side. It consists of a negative lens L74.

An image sensor (not shown) composed of a CCD, CMOS, or the like is arranged on the image plane I.

Based on the above configuration, in the variable magnification optical system of this embodiment, when the magnification is changed from the wide-angle end state (W) to the telescopic end state (T), the first lens group G1 and the second lens group G2 Spacing, spacing between the second lens group G2 and the third lens group G3, spacing between the third lens group G3 and the fourth lens group G4, spacing between the fourth lens group G4 and the fifth lens group G5, the fifth lens The second lens group G2, the fourth lens group G4, and the sixth lens group so that the distance between the group G5 and the sixth lens group G6 and the distance between the sixth lens group G6 and the seventh lens group G7 change, respectively. G6 moves along the optical axis. Specifically, the second lens group G2 moves to the image side, and the fourth lens group G4 and the sixth lens group G6 once move to the object side and then move to the image side. At the time of scaling, the first lens group G1, the third lens group G3, the fifth lens group G5, and the seventh lens group are fixed with respect to the image plane I.

In the variable magnification optical system of this embodiment, the fourth lens group G4 is moved toward the object side along the optical axis as the focusing lens group to focus from an infinity object to a short-range object.

In the variable magnification optical system of this embodiment, a part of the seventh lens group G7 is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs. That is, vibration isolation is performed. The anti-vibration lens group may be a lens group other than the seventh lens group G7, for example, a lens group included in the third lens group.

In this embodiment, the positive meniscus lens L21 corresponds to the first lens, and the positive meniscus lens L25 corresponds to the second lens.

Table 6 below lists the specifications of the variable magnification optical system of this embodiment.

(Table 6)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state
F 123.600 200.000 291.000
F.NO 2.90 2.89 2.88
2ω 19.53 12.07 8.29
TL 341.515 341.515 341.515
BF 54.819 54.819 54.819
Y 21.63 21.63 21.63

[Lens specifications]
m R d nd ν d θ gF
Paraboloid ∞ ∞
1 305.80370 5.200 1.902650 35.77
2 151.95680 13.400 1.497820 82.57
3-731.72780 0.100 1.000000
4 127.79990 13.200 1.433848 95.23
5 1393.36240 D1 1.000000
6 119.73000 8.000 1.720467 34.71 0.583
7 2382.92370 11.843 1.000000
8 157.24410 3.273 1.717360 29.57
9 318.98310 2.850 1.696800 55.52
10 90.66850 3.922 1.000000
11 -963.80580 2.650 1.870705 40.73
12 46.55020 5.472 1.749714 24.66 0.627
13 96.14190 6.392 1.000000
14 -78.01960 2.550 1.834810 42.73
15 -590.82490 D2 1.000000
16 210.56120 5.200 1.755000 52.33
17 -247.05590 0.100 1.000000
18 101.38660 6.800 1.433848 95.23
19 -343.49190 1.528 1.000000
20 -128.08020 4.433 1.654115 39.68
21 92.64210 1.373 1.000000
22 154.41990 4.800 1.910822 35.25
23 -286.77000 D3 1.000000
24 ∞ 4.200 1.804000 46.60
25 -119.33190 0.100 1.000000
26 63.55140 6.700 1.593493 67.00
27 -167.32780 2.000 1.846663 23.78
28 266.30340 D4 1.000000
29 -140.35770 2.000 1.985087 28.56
30 107.93410 4.688 1.000000
31 ∞ 6.600 1.000000 Aperture
32 ∞ 2.200 1.813368 45.82
33 51.52800 6.200 1.740695 49.86
34 -82.95310 D5 1.000000
35 561.09980 2.200 1.806100 40.97
36 89.82510 3.052 1.000000
37 -120.77160 4.300 1.795040 28.69
38 -46.55430 1.800 1.516800 63.88
39 136.17300 7.000 1.000000
40 ∞ D6 1.000000
41 84.49860 5.200 2.001003 29.13
42 -473.11160 2.168 1.000000
43 62.21980 3.000 1.804000 46.60
44 33.62860 10.000 1.487490 70.32
45 -71.24290 6.640 1.000000
46 -66.41450 2.000 1.900433 37.37
47 230.59390 BF 1.000000

[Variable interval data at variable magnification]
Wide-angle end state Intermediate focal length state Telephoto end state
D1 5.100 39.297 64.880
D2 61.280 27.083 1.500
D3 21.293 17.234 18.209
D4 5.786 9.845 8.870
D5 4.000 2.684 3.048
D6 4.103 5.419 5.055

[Each group focal length data]
Focal length
1 1 247.269
2 6 -67.518
3 16 110.138
4 24 85.118
5 29 -152.801
6 35 -83.487
7 41 82.911

[Conditional expression correspondence value]
(1) (-f2) /Δx2= 1.13
(2) f1 / f3 = 2.25
(3) f1 / (-f2) = 3.66
(4) Da21 / Dp21 = 1.48
(5) θgFP1-0.6558 + 0.001982 × νdP1 = -0.004
(6) νdP2 = 24.66
(7) ndP2 + (0.01425 × νdP2) = 2.10
(8) θgFP2 + (0.00316 × νdP2) = 0.71
(9) f1 / (-fRw) = 1.82
(10) β4w = 0.23
(11) β4t / β4w = 0.86

FIG. 12 (a) is a diagram of various aberrations at the time of focusing on an infinity object in the wide-angle end state of the variable magnification optical system of the sixth embodiment, and FIG. 12 (b) is an intermediate diagram of the variable magnification optical system of the sixth embodiment. FIG. 12 (c) is a diagram of various aberrations when the object is in focus at infinity in the focal length state, and FIG. 12 (c) is a diagram of various aberrations when the object is in focus at infinity in the telephoto end state of the variable magnification optical system of the sixth embodiment.

From each aberration diagram, it can be seen that the variable magnification optical system of this embodiment effectively suppresses aberration fluctuations during magnification change and has high optical performance.

According to each of the above embodiments, it is possible to effectively suppress aberration fluctuations during scaling and realize a scaling optical system having high optical performance.

Each of the above examples shows a specific example of the present invention, and the present invention is not limited thereto. The following contents can be appropriately adopted as long as the optical performance of the variable magnification optical system according to the embodiment of the present application is not impaired.

The variable magnification optical system of the present embodiment has a magnification ratio of about 2.4 times. Further, in the variable magnification optical system of the present embodiment, the focal length in the wide-angle end state is about 120 mm in terms of 35 mm. Further, the variable magnification optical system of the present embodiment has an F number of about f / 2.9.

As numerical examples of the variable magnification optical system of the present embodiment, those having a 5-group configuration and those having a 7-group configuration are shown, but the present embodiment is not limited to this, and other group configurations (for example, 6 groups or 8) are shown. It is also possible to construct a variable magnification optical system (more than a group).

Further, in the variable magnification optical system of each of the above embodiments, the entire fourth lens group is the focusing lens group, but a part of any lens group, the entire lens group, or a plurality of lens groups are combined. It may be configured to move in the optical axis direction as a focal lens group. Further, such a focusing lens group can also be applied to autofocus.

Further, in the variable magnification optical system of each of the above examples, a part of the fifth lens group is an anti-vibration lens group, but the whole or a part of any of the lens groups is an anti-vibration lens group and the anti-vibration lens. Image blur caused by camera shake or the like by moving the group along a predetermined movement direction including a component in the direction perpendicular to the optical axis, or rotating (swinging) in the in-plane direction including the optical axis. Can also be configured to correct.

Further, in the variable magnification optical system of each of the above embodiments, the aperture diaphragm is preferably arranged in the fifth lens group, and the lens frame may substitute the role of the aperture diaphragm without providing a member.

Further, the lens surface of the lens constituting the variable magnification optical system of each of the above embodiments may be spherical or flat, or may be aspherical. When the lens surface is spherical or flat, lens processing and assembly adjustment can be facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented, which is preferable. Further, even if the image plane is deviated, the depiction performance is less deteriorated, which is preferable. When the lens surface is aspherical, it can be either an aspherical surface obtained by grinding, a glass mold aspherical surface formed by molding glass into an aspherical shape, or a composite aspherical surface formed by forming a resin provided on the glass surface into an aspherical shape. Good. Further, the lens surface may be a diffraction surface, and the lens may be a refractive index distribution type lens (GRIN lens) or a plastic lens.

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

Next, the camera provided with the variable magnification optical system of the present embodiment will be described with reference to FIG.
FIG. 13 is a schematic view of a camera provided with the variable magnification optical system of the present embodiment.

The camera 1 is an interchangeable lens camera provided with the variable magnification optical system according to the first embodiment as the photographing lens 2.

In the camera 1, the light from an object (subject) (not shown) is focused by the photographing lens 2 and imaged on the focal plate 4 via the quick return mirror 3. The light formed on the focal plate 4 is reflected a plurality of times in the pentaprism 5 and guided to the eyepiece lens 6. As a result, the photographer whose eyes are positioned at the eye point EP can observe the subject image as an upright image.

When the photographer presses the release button (not shown), the quick return mirror 3 retracts out of the optical path, and the light from the subject (not shown) reaches the image sensor 7. As a result, the light from the subject is captured by the image sensor 7 and stored as a subject image in a memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

Here, the variable magnification optical system of the first embodiment mounted on the camera 1 as a photographing lens 2 is a variable magnification optical system that effectively suppresses aberration fluctuations at the time of magnification change and has high optical performance. Therefore, the camera 1 can effectively suppress the aberration fluctuation at the time of scaling and realize high optical performance. Even if a camera equipped with the variable magnification optical system of the second to sixth embodiments is configured as the photographing lens 2, the same effect as that of the camera 1 can be obtained. Further, even when the variable magnification optical system of each of the above embodiments is mounted on a camera having a configuration that does not have a quick return mirror, the same effect as that of the camera 1 can be obtained.

Finally, an outline of the method for manufacturing the variable magnification optical system of the present embodiment will be described with reference to FIG.
FIG. 14 is a flowchart showing an outline of the manufacturing method of the variable magnification optical system of the present embodiment.

The method for manufacturing the variable magnification optical system of the present embodiment shown in FIG. 14 has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power in this order from the object side. A method for manufacturing a variable magnification optical system having a third lens group, a fourth lens group having a positive refractive power, and at least one lens group located on the image side of the fourth lens group, wherein the following step S1 , S2, and S3.

Step S1: In order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a positive refractive power. A group and at least one lens group located on the image side of the fourth lens group are prepared so as to satisfy the following conditional expression (1), and each lens group is arranged in the lens barrel in order from the object side. To do.
(1) 0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance from the wide-angle end state to the telephoto end state of the second lens group when the movement to the image side is positive.

Step S2: By providing a known moving mechanism in the lens barrel, the first lens group is fixed to the image plane at the time of scaling, and the distance between adjacent lens groups changes. To do.

Step S3: An aperture diaphragm is provided on the image side of the fourth lens group.

According to the method for manufacturing a variable magnification optical system of the present embodiment, it is possible to manufacture a variable magnification optical system having high optical performance by effectively suppressing aberration fluctuations during magnification change.

It will be appreciated by those skilled in the art that various changes, substitutions and modifications can be made to this without departing from the spirit and scope of the invention.

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

Claims (20)

From the object side,
First lens group with positive refractive power,
Second lens group with negative refractive power,
Third lens group with positive refractive power,
The fourth lens group having a positive refractive power, and
It has at least one lens group located on the image side of the fourth lens group.
At the time of scaling, the first lens group is fixed to the image plane.
The distance between adjacent lens groups changes,
It has an aperture diaphragm on the image side of the fourth lens group.
A variable magnification optical system that satisfies the following conditional equation.
0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance of the second lens group from the wide-angle end state to the telephoto end state when the movement toward the image side is positive. The variable magnification optical system according to claim 1, which satisfies the following conditional expression.
1.50 <f1 / f3 <3.00
However,
f1: Focal length of the first lens group f3: Focal length of the third lens group The variable magnification optical system according to claim 1 or 2, wherein at least the fourth lens group moves during focusing. The variable magnification optical system according to any one of claims 1 to 3, which satisfies the following conditional expression.
2.50 <f1 / (-f2) <4.50
However,
f1: Focal length of the first lens group f2: Focal length of the second lens group The variable magnification optical system according to any one of claims 1 to 4, wherein a lens component having a positive refractive power is located on the most object side of the second lens group.
The lens component refers to a single lens or a bonded lens. The variable magnification optics according to any one of claims 1 to 5, wherein the distance between the lens component having a positive refractive power located closest to the object side of the second lens group and the subsequent lens component satisfies the following conditional expression. system.
0.50 <Da21 / Dp21 <2.50
However,
Dp21: Thickness on the optical axis of the first lens component, which is a lens component having a positive refractive force located on the most object side of the second lens group Da21: Located on the image side next to the first lens component. Air spacing on the optical axis with the lens component The lens component refers to a single lens or a bonded lens. The variable magnification optical system according to any one of claims 1 to 6, wherein the second lens group includes two or more lenses having at least a positive refractive power. The variable magnification optical system according to any one of claims 1 to 7, wherein the first lens, which is a lens having a positive refractive power located closest to the object side of the second lens group, satisfies the following conditional expression.
−0.015 <θgFP1-0.6558 + 0.001982 × νdP1 <−0.000
However,
νdP1: Abbe number of the glass material used in the first lens θg FP1: Partial dispersion ratio of the glass material used in the first lens At this time, the Abbe number νd and the partial dispersion ratio θgF determine the refractive index with respect to the C line. When the refractive index for the nC and d lines is nd, the refractive index for the F line is nF, and the refractive index for the g line is ng, the values are defined by the following equations:
νd = (nd-1) / (nF-nC)
θgF = (ng-nF) / (nF-nC) The variable magnification optical system according to any one of claims 1 to 8, wherein the second lens group includes a second lens which is a positive lens satisfying all of the following conditional expressions.
18.00 <νdP2 <35.00
1.83 <ndP2 + (0.01425 x νdP2) <2.15
0.702 <θgFP2 + (0.00316 × νdP2)
However,
ndP2: Refractive index of the glass material used in the second lens with respect to the d-line ν dP2: Abbe number of the glass material used in the second lens θgFP2: Partial dispersion ratio of the glass material used in the second lens Then, the Abbe number νd and the partial dispersion ratio θgF are given by the following equations, where nC is the refractive index for the C line, nd is the refractive index for the d line, nF is the refractive index for the F line, and ng is the refractive index for the g line. A value defined by:
νd = (nd-1) / (nF-nC)
θgF = (ng-nF) / (nF-nC) The variable magnification optical system according to any one of claims 1 to 9, wherein the third lens group is fixed at the time of magnification change. The variable magnification optical system according to any one of claims 1 to 10, wherein the lens group on the image side of the fourth lens group has a negative refractive power as a whole in the wide-angle end state. The invention according to any one of claims 1 to 11, wherein the focal length of the first lens group and the focal length of the entire lens group located on the image side of the fourth lens group in the wide-angle end state satisfy the following conditional expression. Variable magnification optical system.
-3.00 <f1 / (-fRw) <3.00
However,
f1: Focal length of the first lens group fRw: Focal length of the entire lens group located on the image side of the fourth lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 12, wherein the fifth lens group adjacent to the image side with respect to the fourth lens group and the diaphragm are fixed to the image plane at the time of scaling. The variable magnification optical system according to any one of claims 1 to 13, wherein the second lens group has at least five or more lenses. The variable magnification optical system according to any one of claims 1 to 14, wherein the aperture diaphragm is located inside a fifth lens group adjacent to the image side of the fourth lens group. The variable magnification optical system according to any one of claims 1 to 15, which satisfies the following conditional expression.
0.05 <β4w <0.70
However,
β4w: Horizontal magnification of the fourth lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 16, which satisfies the following conditional expression.
0.60 <β4t / β4w <1.30
However,
β4w: Lateral magnification of the fourth lens group in the wide-angle end state β4t: Lateral magnification of the fourth lens group in the telephoto end state A claim that all lens surfaces included in the first lens group, the second lens group, the third lens group, the fourth lens group, and the lens group on the image side of the fourth lens group are spherical or flat. Item 2. The variable magnification optical system according to any one of Items 1 to 17. An optical device equipped with the optical system according to any one of claims 1 to 18. From the object side,
First lens group with positive refractive power,
Second lens group with negative refractive power,
Third lens group with positive refractive power,
The fourth lens group having a positive refractive power, and
A method for manufacturing a variable magnification optical system having at least one lens group located on the image side of the fourth lens group.
Configured to satisfy the following conditional expression,
At the time of scaling, the first lens group is fixed with respect to the image plane.
The distance between adjacent lens groups changes,
A method for manufacturing a variable magnification optical system having an aperture diaphragm on the image side of the fourth lens group.
0.70 <(-f2) /Δx2 <1.50
However,
f2: Focal length of the second lens group Δx2: Movement distance of the second lens group from the wide-angle end state to the telephoto end state when the movement toward the image side is positive.