JP2021033242A - Zoom optical system, optical device, and method of manufacturing zoom optical system - Google Patents

Abstract

To provide a zoom optical system which facilitates control of lens group movement directions and is capable of correcting well for aberrations.SOLUTION: A zoom optical system provided herein comprises a leading lens group having negative refractive power and a succeeding lens group, and is configured such that a distance between the leading lens group and the succeeding lens group changes while zooming. The succeeding lens group comprises a first focusing lens group and a second focusing lens group disposed on the image plane side of the first focusing lens group. The first focusing lens group has positive reflective power and is configured to move toward the image plane side along an optical axis while shifting focus from an object at infinity to a nearby object. The second focusing lens group has negative refractive power and is configured to move toward the object side along the optical axis while shifting focus from an object at infinity to a nearby object. The zoom optical system satisfies the following conditional expression: -1.00<MF2w/MF1w<0.00, where MF1w and MF2w respectively represent displacements of the first focusing lens group and the second focusing lens group when shifting focus from an object at infinity to a nearby object, and the displacement toward the image plane side is defined as positive.SELECTED DRAWING: Figure 1

Description

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

A concave-leading zoom lens having a plurality of focus lens groups (see, for example, Patent Document 1) has difficulty in controlling the moving direction of the lens group, and cannot sufficiently correct aberrations such as curvature of field at an intermediate position of zooming. There is. For this reason, there is a demand for a zoom lens that has less control difficulty regarding the movement of the lens group and can satisfactorily correct various aberrations during both scaling and focusing.

JP-A-2015-197593

The variable magnification optical system has a leading lens group having a negative refractive power and a succeeding lens group arranged in order from the object side, and the distance between the leading lens group and the succeeding lens group at the time of scaling. The subsequent lens group has a first focusing lens group and a second focusing lens group arranged on the image plane side of the first focusing lens group. The first focusing lens group has a positive refractive power and moves toward the image plane along the optical axis when focusing from an infinity object to a short-range object. It has a negative refractive power and moves toward the object along the optical axis when focusing from an infinity object to a short-range object, satisfying the following conditional expression.
-1.00 <MF2w / MF1w <0.00
However,
MF1w: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the wide-angle end state MF2w: From an infinity object of the second focusing lens group to a close-range object in the wide-angle end state Amount of movement during focusing (The amount of movement represents the movement toward the image plane as a positive value.)

The optical device is configured to include the above-mentioned variable magnification optical system.

The method for manufacturing the variable magnification optical system is as follows, and each lens group is configured and arranged in the lens barrel. The variable magnification optical system has a leading lens group having a negative refractive power and a succeeding lens group arranged in order from the object side, and the distance between the leading lens group and the succeeding lens group at the time of scaling. The subsequent lens group has a first focusing lens group and a second focusing lens group arranged on the image plane side of the first focusing lens group. The first focusing lens group has a positive refractive power and moves toward the image plane along the optical axis when focusing from an infinity object to a short-range object. It has a negative refractive power and moves toward the object along the optical axis when focusing from an infinity object to a short-range object, satisfying the following conditional expression.
-1.00 <MF2w / MF1w <0.00
However,
MF1w: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the wide-angle end state MF2w: Close distance from the infinity object of the second focusing lens group in the wide-angle end state Amount of movement when focusing on an object (The amount of movement represents the movement toward the image plane as a positive value.)

It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 1. FIG. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the first embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable magnification optical system according to the first embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 2. FIG. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the second embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable-magnification optical system according to the second embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 3. FIG. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the third embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable magnification optical system according to the third embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 4. FIG. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the fourth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable magnification optical system according to the fourth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 5. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the fifth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable-magnification optical system according to the fifth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 6. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the sixth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable-magnification optical system according to the sixth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 7. It is a diagram of various aberrations at the time of focusing on an infinity object of the variable magnification optical system according to the seventh embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable-magnification optical system according to the seventh embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the lens structure of the variable magnification optical system which concerns on Example 8. It is a diagram of various aberrations at the time of focusing an object at infinity of the variable magnification optical system according to the eighth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a diagram of various aberrations at the time of focusing on a close-range object of the variable magnification optical system according to the eighth embodiment, (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. It is a figure which shows the structure of the digital camera which is one Embodiment of an optical apparatus. It is a flowchart which shows the manufacturing method of a variable magnification optical system.

FIG. 25 shows a schematic configuration of a digital camera, which is an embodiment of an optical device. The digital camera 1 is composed of a main body 2 and a photographing lens 3 that can be attached to and detached from the main body 2. The main body 2 includes an image sensor 4, a main body control unit (not shown) that controls the operation of a digital camera, and a liquid crystal operation screen 5. The photographing lens 3 includes a variable magnification optical system ZL composed of a plurality of lens groups and a lens position control mechanism (not shown) for controlling the position of each lens group. The lens position control mechanism is composed of a sensor that detects the position of the lens group, a motor that moves the lens group back and forth along the optical axis, a control circuit that drives the motor, and the like.

The light from the subject is collected by the variable magnification optical system ZL of the photographing lens 3 and reaches the image plane I of the image sensor 4. The light from the subject that has reached the image plane I is photoelectrically converted by the image sensor 4 and recorded as digital image data in a memory (not shown). The digital image data recorded in the memory is displayed on the liquid crystal screen 5 according to the user's operation. Hereinafter, the variable magnification optical system ZL will be described in detail.

The variable magnification optical system in one embodiment has a leading lens group having a negative refractive power and a succeeding lens group arranged in order from the object side, and the leading lens group and the succeeding lens are arranged in order from the object side. The distance from the group changes. The succeeding lens group includes a first focusing lens group and a second focusing lens group arranged on the image plane side of the first focusing lens group. The first focusing lens group has a positive refractive power and moves toward the image plane along the optical axis when focusing from an infinity object to a short-range object. It has a negative refractive power and moves toward the object along the optical axis when focusing from an infinity object to a short-range object, satisfying the following conditional expression (1). The amount of movement represents the movement toward the image plane as a positive value.
-1.00 <MF2w / MF1w <0.00 ... (1)
However,
MF1w: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the wide-angle end state MF2w: From an infinity object of the second focusing lens group to a close-range object in the wide-angle end state In this specification, the "close distance" is the shortest shooting distance (closest end), and the close-range object focusing state is focused on the object at the closest end. It shall mean a state.

As described above, the variable magnification optical system of the present embodiment does not require complicated control because the moving directions of the first and second focusing lens groups are always constant regardless of the zoom position. The conditional expression (1) defines the balance of the amount of movement of the two focusing lens groups when focusing from an infinity object to a close-range object, and satisfies this conditional expression (1). Therefore, when focusing from an infinity object to a close-range object, various aberrations such as curvature of field can be satisfactorily corrected, and aberration fluctuations can be effectively suppressed.

In order to ensure the effect of this embodiment, the upper limit of the conditional expression (1) is a smaller value, for example -0.02, -0.04, -0.06, -0.07, Alternatively, it is preferably −0.08. Further, when the corresponding value of the conditional expression (1) is less than the lower limit value -1.00, the amount of movement of the second focusing lens group becomes relatively large, and it becomes difficult to suppress the aberration fluctuation at the time of focusing. .. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (1) is set to a larger value, for example, -0.80, -0.70, -0.65, -0.60, It is preferably −0.55, −0.50, −0.45, −0.40, −0.38, or −0.35.

By satisfying the above conditional expression in the above configuration, the variable magnification optical system of the present embodiment satisfactorily corrects various aberrations without requiring complicated control regarding the movement of the lens group during focusing, and has high short-distance performance. Can be achieved.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (2).
1.00 <(-f1) / fw <2.00 ... (2)
However,
f1: Focal length of the preceding lens group fw: Focal length when the variable magnification optical system is in focus at an infinity object in the wide-angle end state

Conditional expression (2) defines the range of the focal length of the preceding lens group in the form of the ratio to the focal length of the variable magnification optical system at the time of focusing on an infinity object in the wide-angle end state. By satisfying this conditional expression, it is possible to achieve both miniaturization of the variable magnification optical system and high optical performance.

If the corresponding value of the conditional expression (2) exceeds the upper limit value of 2.00, the power of the preceding lens group becomes too weak, and it becomes difficult to miniaturize the optical system. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (2) is set to a smaller value, for example, 1.90, 1.85, 1.80, 1.75, 1.70. It is preferably 1.65, 1.60, or 1.58.

If the corresponding value of the conditional expression (2) is less than the lower limit value of 1.00, the power of the preceding lens group becomes too strong, and it becomes difficult to satisfactorily correct various aberrations such as curvature of field. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (2) is set to a larger value, for example, 1.10, 1.20, 1.25, 1.28, 1.30, It is preferably 1.33, 1.35, 1.38 or 1.40.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (3).
0.00 <(−f1) / ft <1.00 ... (3)
However,
f1: Focal length of the preceding lens group ft: Focal length when the variable magnification optical system is in focus at infinity in the telephoto end state

Conditional expression (3) defines the range of the focal length of the preceding lens group in the form of a ratio to the focal length of the variable magnification optical system at the time of focusing on an infinity object in the telephoto end state. By satisfying this conditional expression, it is possible to achieve both miniaturization of the variable magnification optical system and high optical performance.

If the corresponding value of the conditional expression (3) exceeds the upper limit value of 1.00, the power of the preceding lens group becomes too weak, and it becomes difficult to miniaturize the optical system. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (3) is set to a smaller value, for example, 0.95, 0.90, 0.85, 0.80, 0.78, It is preferably 0.75, 0.73 or 0.70.

When the corresponding value of the conditional expression (3) is less than the lower limit value of 0.00, the power of the preceding lens group becomes too strong, and it becomes difficult to satisfactorily correct various aberrations such as curvature of field. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (3) is set to a larger value, for example, 0.10, 0.20, 0.30, 0.35, 0.40, It is preferably 0.43, 0.45, 0.48, 0.50, 0.53, or 0.55.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (4).
0.50 <fL1 / f1 <1.50 ... (4)
However,
fL1: Focal length of the first lens from the object side among the lenses constituting the leading lens group f1: Focal length of the leading lens group

Conditional expression (4) expresses the range of the focal length of the first lens (hereinafter referred to as the first lens) from the object side among the lenses constituting the preceding lens group in the form of a ratio to the focal length of the preceding lens group. It is specified. By satisfying this conditional expression, it is possible to achieve both miniaturization of the variable magnification optical system and high optical performance.

If the corresponding value of the conditional expression (4) exceeds the upper limit value of 1.50, the power of the first lens becomes too weak and it becomes difficult to miniaturize the optical system. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (4) is set to a smaller value, for example, 1.45, 1.40, 1.38, 1.35, 1.33. It is preferably 1.30, 1.28, 1.25, 1.23, 1.20, 1.18, or 1.15.

If the corresponding value of the conditional expression (4) is less than the lower limit value of 0.50, the power of the first lens becomes too strong, and it becomes difficult to satisfactorily correct various aberrations such as curvature of field. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (4) is set to a larger value, for example, 0.55, 0.60, 0.65, 0.70, 0.73. It is preferably 0.75, 0.78, 0.80, 0.83, 0.85, 0.88, 0.90, 0.93, or 0.95.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (5).
−0.020 <f1 × Σ (1 / (flk × νdLk)) <0.020 ・ ・ ・ (5)
However,
f1: Focal length of the leading lens group fLk: Focal length of the kth lens from the object side among the lenses constituting the leading lens group νdLk: Abbe number of the kth lens from the object side among the lenses constituting the leading lens group

The conditional expression (5) defines the achromatic function by the preceding lens group. Chromatic aberration can be satisfactorily corrected by selecting a lens that constitutes a preceding lens group so as to satisfy this conditional expression.

If the corresponding value of the conditional expression (5) exceeds the upper limit value of 0.020, it becomes difficult to satisfactorily correct the chromatic aberration of magnification and the like. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (5) is set to a smaller value, for example, 0.018, 0.017, 0.016, 0.015, or 0.014. Is preferable.

Even when the corresponding value of the conditional expression (5) is less than the lower limit value −0.020, it becomes difficult to satisfactorily correct the chromatic aberration of magnification and the like. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (5) is set to a larger value, for example, -0.015, -0.010, -0.005 or 0.000. Is preferable.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (6).
-1.50 <(L1R2-L1R1) / (L1R2 + L1R1) <0.00 ... (6)
However,
L1R1: Radius of curvature of the surface of the lens placed closest to the object side in the variable magnification optical system L1R2: Radius of curvature of the surface of the lens placed closest to the object side on the image plane side

The conditional expression (6) defines the shape factor of the first lens, and indicates that the first lens is a negative meniscus lens with a convex surface facing the object side. By using a lens that satisfies this conditional expression as the first lens, various aberrations can be satisfactorily corrected.

If the corresponding value of the conditional expression (6) exceeds the upper limit value of 0.00, it becomes difficult to satisfactorily correct various aberrations such as curvature of field. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (6) is set to a smaller value, for example, -0.10, -0.20, -0.30, -0.40, It is preferably −0.45, −0.50, −0.55, −0.60, or −0.65.

When the corresponding value of the conditional expression (6) is less than the lower limit value of -1.50, it becomes difficult to satisfactorily correct various aberrations such as coma. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (6) is set to a larger value, for example, -1.40, -1.30, -1.20, -1.10,
It is preferably −1.00, −0.95, −0.90, or −0.85.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (7).
0.00 <(LeR2-LeR1) / (LeR2 + LeR1) <1.00 ... (7)
However,
LeR1: Radius of curvature of the surface of the lens placed closest to the image plane side in the variable magnification optical system LeR2: Radius of curvature of the surface of the lens placed closest to the image plane side

Conditional expression (7) defines the shape factor of the lens arranged on the image plane side of the variable magnification optical system, and the lens closest to the image plane has its convex surface directed to the image plane side. It indicates that it is a positive meniscus lens or a negative meniscus lens.

When the corresponding value of the conditional expression (7) exceeds the upper limit value of 1.00, the lens closest to the image plane becomes a lens having a concave surface facing the image plane side, which causes flare. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (7) is set to a smaller value, for example, 0.90, 0.80, 0.70, 0.65, 0.60, It is preferably 0.55, 0.50, 0.45, or 0.40.

When the corresponding value of the conditional expression (7) is less than the lower limit value of 0.00, the lens closest to the image plane suddenly becomes loose, and it becomes difficult to satisfactorily correct various aberrations such as distortion. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (7) is set to a larger value, for example, 0.03, 0.05, 0.06, 0.75, 0.09, It is preferably 0.10, 0.12 or 0.15.

Further, the variable magnification optical system satisfies the following conditional expression (8) by adopting the above-described configuration.
80.00 ° <2ωw <130.00 ° ... (8)
However,
2ωw: Full angle of view when focusing an object at infinity in the variable magnification optical system at the wide-angle end state

The conditional expression (8) defines the total angle of view of the variable magnification optical system at the time of focusing on an infinity object in the wide-angle end state, and indicates that this variable magnification optical system is a wide-angle zoom lens. The upper limit of the conditional expression (8) can be set to a smaller value, for example, 125.00, 120.00, 115.00, or 110.00 by adjusting the range of the corresponding values of each conditional expression. .. Further, the lower limit value of the conditional expression (8) can be set to a larger value, for example, 85.00, 90.00, or 95.00 by adjusting the range of the corresponding values of each conditional expression.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (9).
0.05 <fw / (-fRw) <0.60 ... (9)
However,
fw: Focal length of the variable magnification optical system when focusing on an infinity object in the wide-angle end state fRw: Focal length when focusing on an infinity object of the lens group after the second focusing lens group in the wide-angle end state

Conditional expression (9) shows a mirrorless-specific configuration in which the lens group after the second focusing lens group is a lens group having a negative refractive power and the optical system is miniaturized by shortening the back focus. There is.

When the corresponding value of the conditional expression (9) exceeds the upper limit value of 0.60, the power of the lens group after the second focusing lens group becomes too strong, and it becomes difficult to satisfactorily correct various aberrations such as distortion. .. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (9) is set to a smaller value, for example, 0.55, 0.52, 0.50, 0.48 or 0.45. It is preferable to do so.

When the corresponding value of the conditional expression (9) is less than the lower limit value of 0.05, the power of the lens group after the second focusing lens group becomes too weak, and the total length of the optical system becomes large. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (9) to a larger value, for example, 0.08, 0.10, 0.12 or 0.15. ..

It is preferable that the variable magnification optical system has an aperture diaphragm arranged in the subsequent lens group and satisfies the following conditional expression (10).
0.35 <STLw / TLw <0.55 ... (10)
However,
STRw: Distance on the optical axis from the aperture stop when focusing on an infinity object in the wide-angle end state TLw: Total length of the variable magnification optical system when focusing on an infinity object in the wide-angle end state

Conditional expression (10) defines the ratio between the distance on the optical axis from the aperture diaphragm to the image plane of the variable magnification optical system in the wide-angle end state and the total length of the optical system, and determines the ratio of the position of the aperture diaphragm. It shows the proper range.

If the corresponding value of the conditional expression (10) exceeds the upper limit value of 0.55, the aperture diaphragm becomes too far from the image plane, and it becomes difficult to secure the peripheral illumination amount. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (10) is set to a smaller value, for example, 0.53, 0.51, 0.49, 0.47, or 0.45. Is preferable.

When the corresponding value of the conditional expression (10) is less than the lower limit value of 0.35, the aperture diaphragm becomes too far from the first lens located closest to the object in the optical system, and it becomes difficult to secure the peripheral illumination amount. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (10) may be set to a larger value, for example, 0.37, 0.39, 0.40, or 0.42. preferable.

It is preferable that the variable magnification optical system has an aperture diaphragm arranged in the subsequent lens group and further satisfies the following conditional expression (11). Here, the aperture diaphragm means a diaphragm that is directly related to the determination of the F value.
0.50 <STLt / TLt <0.75 ... (11)
However,
STRt: Distance on the optical axis from the aperture stop when focusing on an infinity object in the telephoto end state TLt: Overall length of the variable magnification optical system when focusing on an infinity object in the telephoto end state

Conditional expression (11) defines the ratio between the distance on the optical axis from the aperture diaphragm to the image plane of the variable magnification optical system in the telephoto end state and the total length of the optical system, and defines the ratio of the position of the aperture diaphragm. It shows the proper range.

If the corresponding value of the conditional expression (11) exceeds the upper limit value of 0.75, the aperture diaphragm becomes too far from the image plane, and it becomes difficult to secure the peripheral illumination amount. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (11) to a smaller value, for example, 0.73, 0.71, 0.69 or 0.67. ..

If the corresponding value of the conditional expression (11) is less than the lower limit value of 0.50, the aperture diaphragm becomes too far from the first lens located closest to the object in the optical system, and it becomes difficult to secure the peripheral illumination amount. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (11) to a larger value, for example, 0.52, 0.54 or 0.56.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (12).
0.05 <BFw / TLw <0.20 ... (12)
However,
BFw: Back focus of the variable magnification optical system when focusing on an infinity object in the wide-angle end state TLw: Overall length of the variable magnification optical system when focusing on an infinity object in the wide-angle end state

The conditional expression (12) defines the ratio between the back focus of the variable magnification optical system and the total length of the variable magnification optical system, and means that this variable magnification optical system is a mirrorless optical system. ..

If the corresponding value of the conditional expression (12) exceeds the upper limit value of 0.20, the total length of the variable magnification optical system becomes too short, and it becomes difficult to satisfactorily correct various aberrations. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (12) to a smaller value, for example, 0.18, 0.16 or 0.14.

When the corresponding value of the conditional expression (12) is less than the lower limit value of 0.05, the total length of the variable magnification optical system becomes long, and it becomes difficult to miniaturize the optical system. In order to ensure the effect of this embodiment, it is preferable that the lower limit of the conditional expression (12) is a larger value, for example, 0.06, 0.07 or 0.08.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (13).
0.00 <fF1 / (-fF2) <2.00 ... (13)
However,
fF1: Focal length of the first focusing lens group fF2: Focal length of the second focusing lens group

Conditional expression (13) defines the ratio of the focal length of the first focusing lens group to the focal length of the second focusing lens group, and represents an appropriate balance between the focal lengths of the two focusing lens groups. ing.

When the corresponding value of the conditional expression (13) exceeds the upper limit value of 2.00, the power of the first focusing lens group becomes relatively weak, and sufficient optical performance can be ensured when focusing on a short-distance object. It gets harder. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (13) is set to a smaller value, for example, 1.80, 1.60, 1.40, 1.20 or 1.10. It is preferable to do so. Further, even if the power of the first focusing lens group becomes too strong, it becomes difficult to secure sufficient optical performance when focusing on a short-distance object. Therefore, in order to ensure the effect of this embodiment. The lower limit of the conditional expression (13) is preferably set to a larger value, for example, 0.10, 0.20 or 0.30.

Further, it is preferable that the variable magnification optical system further satisfies the following conditional expression (14).
−0.30 <1 / βF1W <0.95 ... (14)
However,
βF1W: Lateral magnification when focusing on an infinity object of the first focusing lens group in the wide-angle end state

The conditional expression (14) defines the lateral magnification of the first focusing lens group when the object is in focus at infinity. By satisfying this conditional expression (14), it is possible to suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object, and to achieve high optical performance over the entire range. it can.

When the corresponding value of the conditional expression (14) exceeds the upper limit value of 0.95, it becomes difficult to suppress fluctuations in various aberrations during focusing. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (14) is set to a smaller value, for example, 0.90, 0.85, 0.80, 0.75, 0.70, 0.65, 0.60, 0.55, 0.50, 0.45, 0.40, 0.38, 0.35, 0.33, 0.30, 0.28, or 0.25 Is preferable.

On the other hand, if the corresponding value of the conditional expression (14) is less than the lower limit value −0.30, it becomes difficult to suppress fluctuations in various aberrations during focusing. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (14) is set to a larger value, for example, -0.25, -0.20, -0.15, -0.10, It is preferably −0.05 or −0.04.

Further, it is preferable that the variable magnification optical system further satisfies the following conditional expression (15).
0.10 <1 / βF2W <1.00 ... (15)
However,
βF2W: Lateral magnification when focusing on an infinity object of the second focusing lens group in the wide-angle end state

The conditional expression (15) defines the lateral magnification of the second focusing lens group when the object is in focus at infinity. By satisfying this conditional equation (15), it is possible to suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object, and to achieve high optical performance over the entire range. it can.

If the corresponding value of the conditional expression (15) exceeds the upper limit value of 1.00, it becomes difficult to suppress fluctuations in various aberrations during focusing. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (15) is set to a smaller value, for example, 0.99, 0.98, 0.96, 0.95, 0.94, It is preferably 0.90, 0.88, 0.85, or 0.84.

On the other hand, if the corresponding value of the conditional expression (15) is less than the lower limit value of 0.10, it becomes difficult to suppress fluctuations in various aberrations during focusing. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (15) is set to a larger value, for example, 0.20, 0.40, 0.60, 0.65, 0.70, It is preferably 0.75 or 0.80.

Further, it is preferable that the variable magnification optical system further satisfies the following conditional expression (16).
{βF1W + (1 / βF1W)} ^-2 <0.250 ... (16)
However,
βF1W: Lateral magnification when focusing on an infinity object of the first focusing lens group in the wide-angle end state

The conditional expression (16) defines the conditions satisfied by the lateral magnification of the first focusing lens group when the object is in focus at infinity. By satisfying this conditional equation (16), it is possible to suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object, and to achieve high optical performance over the entire range. it can.

When the corresponding value of the conditional expression (16) exceeds the upper limit value of 0.250, it becomes difficult to suppress fluctuations in various aberrations during focusing. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (16) is set to a smaller value, for example, 0.240, 0.200, 0.180, 0.150, 0.120, It is preferably 0.100, 0.090, 0.075 or 0.050.

Further, it is preferable that the variable magnification optical system further satisfies the following conditional expression (17).
{βF2W + (1 / βF2W)} ^-2 <0.250 ... (17)
However,
βF2W: Lateral magnification when focusing on an infinity object of the second focusing lens group in the wide-angle end state

The conditional expression (17) defines the conditions satisfied by the lateral magnification of the second focusing lens group at the time of focusing on an infinite object. By satisfying this conditional expression (17), it is possible to suppress fluctuations in various aberrations such as spherical aberration when focusing from an infinity object to a short-distance object, and to achieve high optical performance over the entire range. it can.

If the corresponding value of the conditional expression (17) exceeds the upper limit value of 0.250, it becomes difficult to suppress fluctuations in various aberrations during focusing. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (17) is set to a smaller value, for example, 0.2499, 0.2498, 0.2495, 0.3490, 0.2485, It is preferably 0.2480, 0.2470, 0.2450, or 0.2430.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (18).
1.50 <fF1 / fBw <3.50 ... (18)
However,
fF1: Focal length of the first focusing lens group fBw: Combined focal length of the succeeding lens group in the wide-angle end state

Conditional expression (18) defines the ratio between the focal length of the first focusing lens group and the focal length of the succeeding lens group in the wide-angle end state. By satisfying this conditional expression (18), various aberrations can be satisfactorily corrected from the infinite object in-focus state to the short-distance object in-focus state, and the aberration fluctuation can be suppressed.

If the corresponding value of the conditional expression (18) exceeds the upper limit value of 3.50, the power of the first focusing lens group becomes too weak, and it becomes difficult to secure sufficient optical performance in the short-distance object focusing state. .. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (18) is set to a smaller value, for example, 3.40, 3.30, 3.20, 3.10, 3.00. It is preferably 2.90 or 2.80.

When the corresponding value of the conditional expression (18) is less than the lower limit value of 1.50, the power of the first focusing lens group becomes strong, and it becomes difficult to secure sufficient optical performance in the short-distance object focusing state. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (18) is set to a larger value, for example, 1.60, 1.70, 1.80, 1.90, 2.00 or It is preferably 2.10.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (19).
0.10 <fRw / fF2 <0.80 ... (19)
However,
fRw: Focal length of the lens group after the second focusing lens group in the wide-angle end state when focusing on an infinity object fF2: Focal length of the second focusing lens group

Conditional expression (19) defines an appropriate ratio between the focal length of the lens group after the second focusing lens group at the time of focusing on an infinity object in the wide-angle end state and the focal length of the second focusing lens group. It is a thing. By satisfying this conditional expression, high optical performance can be ensured during short-distance shooting.

If the corresponding value of the conditional expression (19) exceeds the upper limit value of 0.80, the power of the second focusing lens group becomes too weak, and it becomes difficult to secure the short-distance performance. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (19) is set to a smaller value, for example, 0.75, 0.70, 0.68, 0.65, 0.63, It is preferably 0.60, 0.58, 0.55, or 0.53.

When the corresponding value of the conditional expression (19) is less than the lower limit value of 0.10, the power of the second focusing lens group becomes too strong, and it becomes difficult to secure the short-distance performance. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (19) is set to a larger value, for example, 0.15, 0.18, 0.20, 0.23, 0.24, Alternatively, it is preferably 0.25.

The variable magnification optical system has an intermediate lens group including at least one lens between the first focusing lens group and the second focusing lens group, and can satisfy the following conditional expression (20). preferable.
0.20 <fw / fAw <0.80 ... (20)
However,
fw: Focal length when focusing an object at infinity of the variable magnification optical system in the wide-angle end state fAw: Combined focal length of the intermediate lens group in the wide-angle end state

Conditional expression (20) defines the ratio between the focal length of the variable magnification optical system and the combined focal length of the intermediate lens group between the first in-focus lens group and the second in-focus lens group. It shows that the two focusing lens groups are not adjacent to each other, but are arranged with an intermediate lens group in between. By satisfying this conditional expression, various aberrations can be satisfactorily corrected when focusing from an infinite object to a short-distance object.

When the corresponding value of the conditional expression (20) exceeds the upper limit value of 0.80, the power of the intermediate lens group becomes strong, and it becomes difficult to satisfactorily correct various aberrations such as coma. In order to ensure the effect of the present embodiment, the upper limit of the conditional expression (20) is set to a smaller value, for example, 0.75, 0.70, 0.68, 0.65, 0.63, It is preferably 0.60, 0.58, or 0.55.

When the corresponding value of the conditional expression (20) is less than the lower limit value of 0.20, the power of the intermediate lens group becomes weak, and the aberration correction obtained by arranging the intermediate lens group between the two focusing lens groups, etc. It becomes difficult to obtain the effect. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (20) is set to a larger value, for example, 0.22, 0.25, 0.28, 0.30 or 0.32. It is preferable to do so.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (21).
0.30 <dF1w / TLw <0.50 ... (21)
However,
dF1w: From the object-side surface of the lens placed closest to the object side in the variable magnification optical system when focusing on an infinity object in the wide-angle end state, the object side most in the first focusing lens group Distance on the optical axis to the object-side surface of the lens placed in TLw: Total length of the variable magnification optical system at the wide-angle end state when the object is in focus at infinity.

In the conditional equation (21), the surface of the lens arranged on the object side most in the variable magnification optical system is on the object side of the lens arranged on the object side most in the first focusing lens group. It defines the ratio of the distance on the optical axis to the surface and the total length of the variable magnification optical system, and indicates an appropriate range of the position of the first focusing lens group in the variable magnification optical system. The range defined by the conditional expression (21) means that the first focusing lens group is arranged in front of the optical system (closer to the object) and the two focusing lens groups are separated from each other, and this conditional expression is satisfied. As a result, various aberrations such as curvature of field can be satisfactorily corrected.

When the corresponding value of the conditional expression (21) exceeds the upper limit value of 0.50, the position of the first focusing lens group is lowered too much (away from the object), and the optical system becomes large. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (21) is set to a smaller value, for example, 0.48, 0.46, 0.
.. It is preferably 45 or 0.44.

When the corresponding value of the conditional expression (21) is less than the lower limit value of 0.30, the first focusing lens group protrudes too far forward (closer to the object), and various aberrations such as coma can be satisfactorily corrected. It gets harder. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (21) to a larger value, for example, 0.32, 0.34, 0.36 or 0.38. ..

It is preferable that the variable magnification optical system further satisfies the following conditional expression (22).
0.60 <dF2w / TLw <0.90 ... (22)
However,
dF2w: From the object-side surface of the lens placed closest to the object side in the variable magnification optical system when focusing on an infinity object in the wide-angle end state, the object side most in the second focusing lens group Distance on the optical axis to the object-side surface of the lens placed in TLw: Total length of the variable magnification optical system at the wide-angle end state when the object is in focus at infinity.

In the conditional equation (22), the surface of the lens arranged on the object side most in the variable magnification optical system is on the object side of the lens arranged on the object side most in the second focusing lens group. It defines the ratio of the distance on the optical axis to the surface to the total length of the variable magnification optical system when the object is in focus at infinity, and the position of the second focusing lens group in the variable magnification optical system is appropriate. Shows the range. The range defined by the conditional expression (22) means that the second focusing lens group is arranged behind the optical system (closer to the image plane) and the two focusing lens groups are separated from each other. By satisfying the requirements, various aberrations such as curvature of field can be satisfactorily corrected.

Since the image plane is arranged behind the second focusing lens group, there is a physical limit to the arrangement position when the second focusing lens group is moved toward the image plane side. The upper limit value of 0.90 in the conditional expression (22) indicates this physical limit. The upper limit of the conditional expression (22) may be a smaller value, for example 0.88, 0.86, 0.85, or 0.84, in order to ensure the effect of the present embodiment. preferable.

When the corresponding value of the conditional expression (22) is less than the lower limit value of 0.60, the second focusing lens group protrudes too far forward, and it becomes difficult to sufficiently correct various aberrations. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (22) is set to a larger value, for example, 0.65, 0.68, 0.70, 0.73, or 0.75. Is preferable.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (23).
-1.00 <MF2t / MF1t <0.00 ... (23)
However,
MF1t: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the telephoto end state MF2t: From an infinity object of the second focusing lens group to a close-range object in the telephoto end state Amount of movement during focusing (The amount of movement represents the movement toward the image plane as a positive value.)

Conditional expression (23) defines the ratio of the amount of movement of the first focusing lens group to the amount of movement of the second focusing lens group when focusing from an infinity object to a close-range object in the telephoto end state. This indicates that the amount of movement of the first focusing group is larger than the amount of movement of the second focusing group.

When focusing from an infinity object to a close-range object, the first focusing lens group and the second focusing lens group move in different directions, so the corresponding value of the conditional expression (23) is the upper limit. It does not exceed the value of 0.00. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (23) is set to a smaller value, for example, −0.10, −0.20, −0.30 or −0.35. It is preferable to do so.

If the corresponding value of the conditional expression (23) is less than the lower limit value -1.00, various aberrations such as curvature of field cannot be satisfactorily corrected, and it becomes difficult to suppress aberration fluctuations during short-distance shooting. .. In order to ensure the effect of this embodiment, the lower limit of the conditional expression (23) is set to a larger value, for example, -0.90, -0.80, -0.70 or -0.60. It is preferable to do so.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (24).
0.00 <(1-βF2w ² ) × βRw ² × MF2w <1.00 ... (24)
However,
βF2w: Lateral magnification when the second in-focus lens group is in focus at the wide-angle end state βRw: Total magnification of the lens group after the second in-focus lens group in the wide-angle end state MF2w: Second focus in the wide-angle end state Amount of movement during focusing from an infinite object in the focal lens group to a close-range object

The conditional equation (24) defines the moving direction of the second focusing lens group, and shows that the second focusing lens group corrects the motion aberration in the direction opposite to the direction for focusing. There is. By satisfying this conditional expression, it is possible to satisfactorily correct various aberrations and suppress aberration fluctuations during focusing without increasing the size of the optical system.

If the corresponding value of the conditional expression (24) exceeds the upper limit value of 1.00, the amount of movement for focusing increases too much, and it becomes difficult to miniaturize the optical system. In order to ensure the effect of the present embodiment, it is preferable to set the upper limit value of the conditional expression (24) to a smaller value, for example, 0.90, 0.80, 0.70 or 0.65. ..

When the corresponding value of the conditional expression (24) is less than the lower limit value of 0.00, it becomes difficult to suppress the fluctuation of the curvature of field when the short-distance object is in focus. In order to ensure the effect of the present embodiment, it is preferable to set the lower limit value of the conditional expression (24) to a larger value, for example, 0.01, 0.02 or 0.03.

It is preferable that the variable magnification optical system further satisfies the following conditional expression (25).
0.50 << | βF2w / βF2t | <5.00 ... (25)
However,
βF2w: Lateral magnification when the second in-focus lens group is in focus at the wide-angle end state βF2t: Lateral magnification when the second in-focus lens group is in focus at the telephoto end state

Conditional expression (25) includes the lateral magnification of the second focusing lens group at the time of focusing on the infinity object in the wide-angle end state and the lateral magnification of the second focusing lens group at the time of focusing on the infinity object in the telephoto end state. The second focusing lens group has a small change in magnification at the time of magnification change, and the efficacy of the second focusing lens group remains constant from the wide-angle end state to the telephoto end state. It is shown that.

If the corresponding value of the conditional expression (25) exceeds the upper limit value of 5.00, the lateral magnification of the second focusing lens group in the wide-angle end state becomes too large, and sufficient optical performance can be ensured during short-distance focusing. It gets harder. In order to ensure the effect of this embodiment, the upper limit of the conditional expression (25) is set to a smaller value, for example, 4.00, 3.00, 2.00 1.50 or 1.00. Is preferable.

When the corresponding value of the conditional expression (25) is less than the lower limit value of 0.50, the amount of movement of the second focusing lens group at the time of focusing in the wide-angle end state becomes too large, and the entire optical system becomes large. In order to ensure the effect of the present embodiment, the lower limit of the conditional expression (25) is set to a larger value, for example, 0.55, 0.60, 0.65, 0.70, 0.75 or 0.75. It is preferably 0.80.

Subsequently, the manufacturing method of the variable magnification optical system will be outlined with reference to FIG. 26. In order from the object side, the leading lens group having a negative refractive power and the succeeding lens group are arranged side by side so that the distance between the leading lens group and the succeeding lens group changes at the time of magnification change (ST1). The succeeding lens group has a first focusing lens group and a second focusing lens group arranged on the image plane side of the first focusing lens group, and the first focusing lens group has a positive refraction. It has a force and moves toward the image plane along the optical axis when focusing from an infinity object to a short-range object, and the second focusing lens group has a negative refractive power and is an infinity object. When focusing on a short-range object, the lens is configured to move toward the object along the optical axis (ST2). Each lens group is configured and arranged in the lens barrel so as to satisfy the following conditional expression (ST3).
-1.00 <MF2w / MF1w <0.00
However,
MF1w: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the wide-angle end state MF2w: Close distance from the infinity object of the second focusing lens group in the wide-angle end state Amount of movement when focusing on an object (The amount of movement represents the movement toward the image plane as a positive value.)

The variable magnification optical system manufactured by the above procedure and the optical device equipped with the variable magnification optical system have the first focusing lens group on the image plane side when focusing from an infinity object to a short-range object. The second focusing lens group moves to the object side. Since the moving direction of the in-focus lens group is constant regardless of the zoom position, various aberrations are satisfactorily corrected when the lens group is moved without complicated control, and high optics is achieved in a short-range object in-focus state. Performance can be achieved.

Hereinafter, the variable magnification optical system will be further described with reference to eight numerical examples from Example 1 to Example 8. First, how to read the figures and tables referred to in the explanation of each embodiment will be described. 1, FIG. 4, FIG. 7, FIG. 10, FIG. 13, FIG. 16, FIG. 19 and FIG. 22 show the arrangement of the lens group of the variable magnification optical system in each embodiment by a cross-sectional view. In the lower part of each figure, the movement loci along the optical axis of the lens group G and the aperture S when zooming (magnifying) from the wide-angle end state (W) to the telephoto end state (T) are indicated by arrows. In the upper part of each figure, the moving direction of the focusing lens group when focusing from an infinity object to a short-range object is indicated by an arrow together with the letters "focus" and "∞".

In these figures, each lens group is represented by a combination of reference numerals G and numbers, and each lens is represented by a combination of reference numerals L and numbers. In this specification, in order to prevent complication due to an increase in reference numerals, numbers are assigned to each embodiment. Therefore, the same combination of reference numerals and numbers may be used in a plurality of examples, but this does not mean that the configurations indicated by the combination of reference numerals and numbers are the same.

2, FIG. 5, FIG. 8, FIG. 11, FIG. 14, FIG. 17, FIG. 20, and FIG. 23 are aberration diagrams of the variable magnification optical system at the time of focusing on an infinity object in each embodiment, respectively (A). ) Indicates various aberrations in the wide-angle end state, and (B) indicates various aberrations in the telephoto end state. 3, FIG. 6, FIG. 9, FIG. 12, FIG. 15, FIG. 18, FIG. 21 and FIG. 24 are aberration diagrams of the variable magnification optical system at the time of focusing on a close-range object in each embodiment, respectively. (A) shows various aberrations in the wide-angle end state, and (B) shows various aberrations in the telephoto end state. In these figures, FNO indicates F number, NA indicates numerical aperture, and Y indicates image height. The spherical aberration diagram shows the value of the F number or numerical aperture corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the transverse aberration diagram shows the value of each image height.
d represents the d line (λ = 587.6 nm) and g represents the g line (λ = 435.8 nm). In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. The distortion diagram shows the distortion aberration based on the d-line, and the chromatic aberration of magnification diagram shows the chromatic aberration of magnification based on the g-line.

Subsequently, the table used for explaining each embodiment will be described. In the [Overall specifications] table, f is the focal length of the entire lens system, FNO is the F number, 2ω is the angle of view (unit is ° (degrees), and ω is the half angle of view), and Y is the maximum image height. Is shown. TL indicates the distance from the frontmost surface of the lens to the final surface of the lens on the optical axis when the infinity object is in focus, plus BF, and BF is the final surface of the lens on the optical axis when the infinity object is in focus. The air conversion distance (back focus) from the image plane I to the image plane I is shown.

In the [Lens Specifications] table, the surface numbers indicate the order of the optical surfaces from the object side along the direction in which the light beam travels, and R is the radius of curvature of each optical surface (the surface whose center of curvature is located on the image surface side). Is a positive value), D is the distance on the optical axis from each optical surface to the next optical surface (or image surface), nd is the refractive index of the material of the optical member with respect to the d line, and νd is The Abbe number based on the d-line of the material of the optical member is shown. The surface spacing (Di) means that the distance from one surface i to the next surface is variable. S indicates an aperture diaphragm, and "∞" of the radius of curvature indicates a plane or an aperture. The description of the refractive index nd of air = 1.00000 is omitted. When the lens surface is aspherical, the surface number is marked with * and the radius of curvature R indicates the paraxial radius of curvature.

In the table of [Aspherical surface data], the shape of the aspherical surface shown in [Lens specifications] is shown by the following equation (A). X (y) is the distance (zag amount) along the optical axis direction from the tangent plane at the aspherical apex to the position on the aspherical surface at the height y, and R is the radius of curvature of the reference sphere (near-axis radius of curvature). , Kappa is the conical constant, and Ai is the i-order aspherical coefficient. "E-n" indicates "x10-n". For example, 1.234E-05 = 1.234 × 10-5. The second-order aspherical coefficient A2 is 0, and the description thereof is omitted.
X (y) = (y2 / R) / {1+ (1-κ × y2 / R2) 1/2} + A4 × y4 + A6 × y6 + A8 × y8 + A10 × y10 + A12 × y12 ・ ・ ・ (A)

The [Lens Group Data] table shows the starting surface (the surface closest to the object) of each lens group, the focal length, the magnification when the infinity object is in focus at the wide-angle end state, and the infinity object at the telephoto end state. Shows the magnification when in focus. The table of [first lens group data] shows the focal lengths of the lenses constituting the first lens group shown in the lens group data.

The table of [variable spacing data] shows the surface spacing to the next surface at the surface number i in which the surface spacing is (Di) in the table showing [lens specifications]. The two columns on the left show the surface spacing when focusing on an infinite object, and the two columns on the right show the surface spacing when focusing on a close-range object.

Since "mm" is generally used as the unit of the focal length f, the radius of curvature R, the surface spacing D, and other lengths, the unit of length is set to "mm" in each table of the present specification. There is. However, since the variable magnification optical system can obtain the same optical performance even if it is proportionally expanded or contracted, the unit of length is not necessarily limited to "mm".

The explanations of the figures and tables up to this point are common to all the examples, and the duplicated explanations below will be omitted.

(Example 1)
The first embodiment will be described with reference to FIGS. 1, 2, 3 and 1. FIG. 1 is a diagram showing a lens configuration of the variable magnification optical system ZL (1) according to the first embodiment. In the variable magnification optical system ZL (1), the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the second lens group G2 having a negative refractive power are arranged in order from the object side. It is composed of three lens groups G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. The image plane I is located after the fifth lens group G5. The first sub-aperture ss1 is arranged in the second lens group G2, and the aperture diaphragm S and the second sub-aperture ss2 are arranged in the third lens group G3. The first in-focus lens group F1 is composed of a part of the lens groups in the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the fifth lens group G5. Will be done.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 1 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens groups (following lens groups) from the second lens group G2 to the fifth lens group G5 move to the object side, and the first lens group G1 and the succeeding lens By changing the distance between the groups, the shooting magnification is changed (magnification is performed). At the time of scaling, the second lens group G2 including the first focusing lens group F1 and the fifth lens group G5 including the second focusing lens group F2 move in the same direction by the same distance (movement locus is Will be the same). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, a biconcave negative lens L13, and a biconvex positive lens L14. Consists of. Both sides of the negative meniscus lens L11 are aspherical, and the image-side surface of the negative meniscus lens L12 is aspherical.

The second lens group G2 includes a combined positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, a first sub-throttle ss1, and a positive meniscus lens having a convex surface facing the object side. It is composed of L23, a negative meniscus lens L24 with a convex surface facing the object side, and a junction positive lens of a biconvex positive lens L25. Of these, the junction positive lens of the negative meniscus lens L21 and the biconvex positive lens L22 functions as the first focusing lens group F1.

The third lens group G3 includes an aperture stop S, a negative meniscus lens L31 with a concave surface facing the object side, a biconcave negative lens L32, a biconvex positive lens L33, and a second sub-aperture ss2. Consists of.

The fourth lens group G4 includes a joint positive lens of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42, a biconvex positive lens L43, and a negative meniscus lens with a concave surface facing the object side. It is composed of a L44 junction positive lens.

The fifth lens group G5 is composed of a biconvex positive lens L51, a biconcave negative lens L52, and a negative meniscus lens L53 with a concave surface facing the object side. Of these, the positive lens L51 and the negative lens L52 function as the second focusing lens group F2. The image-side surface of the negative lens L52 and the image-side surface of the negative meniscus lens L53 are aspherical surfaces.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is a lens group from the secondary aperture ss1 in the second lens group G2 to the negative meniscus lens L44 of the fourth lens group G4. Yes, the lens group GR after the second focusing lens group is the fifth lens group G5.

Table 1 lists the values of the specifications of the variable magnification optical system according to the first embodiment.
(Table 1)
[Overall specifications]
Variable ratio = 2.061
WT
f 16.500 34.000
F.NO 2.910 2.910
2ω (°) 105.504
Ymax 20.787 21.700
TL 157.563 147.452
BF 14.914 34.732
MF1 3.954 4.587
MF2 -1.009 -1.746
fAw 43.772
fBw 37.589
fRw -67.020
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 104.5721 2.800 1.82098 42.50
2 * 17.0784 9.901
3 60.0168 2.000 1.82098 42.50
4 * 39.8844 8.959
5 -47.0446 1.700 1.45600 91.37
6 99.5616 0.200
7 69.7654 4.418 2.00069 25.46
8-360.6089 (D8)
9 50.9989 1.100 1.96300 24.11
10 26.0000 5.600 1.67270 32.18
11 -343.9963 (D11)
12 0.0000 0.000
13 51.3179 3.600 1.81666 29.30
14 546.1825 0.200
15 55.6602 1.200 1.84666 23.80
16 25.9737 8.100 1.48749 70.32
17 -49.8592 (D17)
18 (S) 0.0000 3.685
19 -47.2832 1.100 1.95375 32.33
20 -294.7144 1.387
21 -67.3393 1.100 1.95375 32.33
22 97.3774 0.200
23 40.3224 3.300 1.92286 20.88
24-773.0582 1.500
25 0.0000 (D25)
26 73.8132 1.100 1.95375 32.33
27 20.7413 6.000 1.49782 82.57
28 -161.3154 0.200
29 26.6960 9.300 1.49782 82.57
30 -23.8740 1.200 1.95375 32.33
31 -34.0639 (D31)
32 636.0259 3.550 1.80809 22.74
33 -42.6926 0.200
34 -54.4744 1.400 1.85108 40.12
35 * 98.1829 (D35)
36 -22.0542 1.400 1.82098 42.50
37 * -32.0038 (D37)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = -1.00559E-06, A6 = 5.63388E-09, A8 = -7.40263E-12, A10 = 3.87300E-15
Second side κ = 0.000
A4 = 3.60660E-06, A6 = 9.14891E-09, A8 = 1.27298E-11, A10 = 1.51889E-13
Fourth side κ = 1.0000
A4 = 4.88200E-06, A6 = 4.07550E-09, A8 = -1.87588E-11, A10 = -1.59526E-14
Side 35 κ = 1.0000
A4 = 1.16601E-05, A6 = 1.03251E-08, A8 = -1.15486E-10, A10 = 1.04650E-12
Side 37 κ = 1.0000
A4 = 6.02570E-06, A6 = 7.33824E-09, A8 = 2.29245E-10, A10 = -9.55354E-13
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -23.346 0.000 0.000
2 9 32.353
2-1 (F1) 9 102.890 4.383 1.926
2-2 13 40.878 -0.127 -0.599
3 18 -61.428 2.485 6.721
4 26 45.517 0.399 0.119
5 32 -67.020
5-1 (F2) 32 -253.066 1.070 1.117
5-2 36 -92.261 1.190 1.405
[First lens group data]
Lens focal length
L11 -25.227
L12 -151.617
L13 -69.809
L14 58.717
[Variable interval data]
Infinity close
W T W T
F 16.50000 34.00000 -0.11860 -0.23288
D0 0.0000 0.0000 115.8709 125.4201
D8 31.42890 1.50000 35.52504 6.54836
D11 7.01271 7.01271 2.89868 2.00000
D17 1.00090 4.70395 1.00090 4.70395
D25 6.55312 0.00000 6.55312 0.00000
D31 2.84830 5.69835 2.00000 4.37744
D35 7.40501 7.40501 8.27637 8.71593
D37 14.91437 34.73214 15.05178 35.16746

FIG. 2 shows various aberration values of the variable magnification optical system according to the first embodiment in the infinity object in-focus state, and FIG. 3 shows various aberration values of the variable-magnification optical system according to the first embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the first embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 2)
The second embodiment will be described with reference to FIGS. 4, 5, 6 and 2. FIG. 4 is a diagram showing a lens configuration of the variable magnification optical system ZL (2) according to the second embodiment. In the variable magnification optical system ZL (2), the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the second lens group G2 having a negative refractive power are arranged in order from the object side. It is composed of three lens groups G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. The image plane I is located after the fifth lens group G5. The first sub-aperture ss1 is arranged in the second lens group G2, and the aperture diaphragm S and the second sub-aperture ss2 are arranged in the third lens group G3. The first in-focus lens group F1 is composed of a part of the lens groups in the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the fifth lens group G5. Will be done.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 4 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens group (successor lens group) moves from the second lens group G2 to the fifth lens group G5 to the object side, and the first lens group G1 and the succeeding lens group By changing the interval, the shooting magnification is changed (magnification is performed). At the time of scaling, the second lens group G2 including the first focusing lens group F1 and the fifth lens group G5 including the second focusing lens group F2 move in the same direction by the same distance (movement locus is Will be the same). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 includes a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, a biconcave negative lens L13, and a positive lens L13 having a convex surface facing the object side. It is composed of a meniscus lens L14. Both sides of the negative meniscus lens L11 are aspherical, and the image-side surface of the negative meniscus lens L12 is aspherical.

The second lens group G2 includes a combined positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22, a first sub-aperture ss1, and a negative meniscus lens having a convex surface facing the object side. It is composed of an L23 and a junction normal lens of a biconvex positive lens L24. Of these, the junction positive lens of the negative meniscus lens L21 and the positive lens L22 functions as the first focusing lens group F1.

The third lens group G3 includes an aperture diaphragm S, a negative meniscus lens L31 with a concave surface facing the object side, a negative lens L32 having a biconcave shape, a positive meniscus lens L33 with a convex surface facing the object side, and a second lens group G3. It is composed of a sub-throttle ss2.

The fourth lens group G4 includes a joint positive lens of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42, a biconvex positive lens L43, and a negative meniscus lens with a concave surface facing the object side. It is composed of a L44 junction positive lens.

The fifth lens group G5 is composed of a biconvex positive lens L51, a biconcave negative lens L52, and a negative meniscus lens L53 with a concave surface facing the object side. Of these, the positive lens L51 and the negative lens L52 function as the second focusing lens group F2. The image-side surface of the negative lens L52 and the image-side surface of the negative meniscus lens L53 are aspherical surfaces.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is the second lens group.
It is a lens group from the secondary aperture ss1 in the lens group G2 to the negative meniscus lens L44 of the fourth lens group G4, and the lens group GR after the second focusing lens group is the fifth lens group G5.

Table 2 lists the values of the specifications of the variable magnification optical system according to the second embodiment.
(Table 2)
[Overall specifications]
Variable ratio = 2.061
WT
f 16.500 34.000
F.NO 2.910 2.910
2ω (°) 105.248
Ymax 21.033 21.700
TL 149.126 141.722
BF 15.453 35.329
MF1 3.517 3.824
MF2 -0.565 -1.601
fAw 40.847
fBw 35.127
fRw -92.766
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 118.8647 2.700 1.82098 42.50
2 * 17.5000 8.594
3 41.7389 2.000 1.67798 54.89
4 * 32.0000 9.245
5 -55.5967 1.700 1.49782 82.57
6 46.3811 0.200
7 45.5029 4.961 1.99483 28.47
8 1385.3061 (D8)
9 41.9314 1.100 1.96300 24.11
10 25.0000 6.000 1.62090 34.83
11 -153.6347 (D11)
12 0.0000 0.000
13 38.0305 1.200 1.84666 23.80
14 26.0000 7.700 1.51680 64.13
15 -46.5722 (D15)
16 (S) 0.0000 3.928
17 -37.4881 1.100 1.92500 32.91
18 -323.2842 0.973
19 -120.3322 1.100 1.93008 25.44
20 110.3524 0.201
21 39.3475 3.400 1.94594 17.98
22 2909.2958 1.500
23 0.0000 (D23)
24 80.1013 1.100 1.95375 32.33
25 22.0000 6.000 1.49782 82.57
26 -119.8164 0.200
27 25.5302 9.200 1.49782 82.57
28 -23.9199 1.200 1.95375 32.33
29 -34.8127 (D29)
30 73.0708 3.200 1.74658 24.84
31 -84.2485 0.200
32 -97.8502 1.400 1.85108 40.12
33 * 50.2240 (D33)
34 -22.3892 1.400 1.82098 42.50
35 * -32.6057 (D35)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = 1.33764E-06, A6 = 4.41212E-09, A8 = -6.87879E-12, A10 = 3.85112E-15
Second side κ = 0.000
A4 = 3.80490E-06, A6 = 1.58389E-08, A8 = 4.55970E-11, A10 = 5.22229E-14
Fourth side κ = 1.0000
A4 = 8.25030E-06, A6 = 4.07493E-09, A8 = -4.58748E-11, A10 = 1.89532E-14
Side 33 κ = 1.0000
A4 = 1.25151E-05, A6 = 1.40234E-08, A8 = -9.16608E-11, A10 = 1.553575E-12
Side 35 κ = 1.0000
A4 = 9.13952E-06, A6 = 2.24452E-09, A8 = 3.26258E-10, A10 = -1.6541E-12
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -23.287 0.000 0.000
2 9 33.243
2-1 (F1) 9 75.154 -225.238 2.789
2-2 12 49.638 0.003 -0.510
3 16 -74.008 2.398 8.278
4 24 42.611 0.344 0.075
5 30 -59.330
5-1 (F2) 30 -166.110 1.096 1.167
5-2 34 -92.766 1.194 1.409
[First lens group data]
Lens focal length
L11 -25.300
L12 -220.588
L13 -50.514
L14 47.206
[Variable interval data]
Infinity close
W T W T
F 16.50000 34.00000 -0.11175 -0.22221
D0 0.00000 0.00000 122.8324 131.3109
D8 28.84193 1.56265 32.48101 5.79443
D11 6.20662 6.20662 2.55638 1.99804
D15 1.20005 4.72090 1.20005 4.72090
D23 5.73043 0.00000 5.73043 0.00000
D29 2.50363 4.71316 2.07152 3.49673
D33 7.68870 7.68870 8.12832 8.88453
D35 15.45292 35.32876 15.57830 35.73388

FIG. 5 shows various aberration values of the variable magnification optical system according to the second embodiment in the infinity object in-focus state, and FIG. 6 shows various aberration values of the variable-magnification optical system according to the second embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the second embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 3)
Example 3 will be described with reference to FIGS. 7, 8, 9, and 3. FIG. 7 is a diagram showing a lens configuration of the variable magnification optical system ZL (3) according to the third embodiment. In the variable magnification optical system ZL (3), the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the second lens group G2 having a negative refractive power are arranged in order from the object side. It is composed of three lens groups G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. The image plane I is located after the fifth lens group G5. The first sub-aperture ss1 is arranged in the second lens group G2, and the aperture diaphragm S and the second sub-aperture ss2 are arranged in the third lens group G3. The first in-focus lens group F1 is composed of a part of the lens groups in the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the fifth lens group G5. Will be done.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 7 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens groups (following lens groups) from the second lens group G2 to the fifth lens group G5 move to the object side, and the first lens group G1 and the succeeding lens group The shooting magnification is changed (magnification is performed) by changing the interval between the lenses. At the time of scaling, the second lens group G2 including the first focusing lens group F1 and the fifth lens group G5 including the second focusing lens group F2 move in the same direction by the same distance (movement locus is Will be the same). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 is a combination of a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, a biconcave negative lens L13, and a biconvex positive lens L14. It consists of a negative lens. Both sides of the negative meniscus lens L11 are aspherical, and the image-side surface of the negative meniscus lens L12 is aspherical.

The second lens group G2 includes a first sub-aperture ss1, a negative meniscus lens L21 having a convex surface facing the object side, a junction positive lens of a biconvex positive lens L22, and a negative meniscus lens having a convex surface facing the object side. It is composed of an L23 and a junctioned positive lens of a biconvex positive lens L24. Of these, the junction positive lens of the negative meniscus lens L21 and the biconvex positive lens L22 functions as the first focusing lens group F1.

The third lens group G3 is composed of an aperture stop S, a biconcave negative lens L31, a biconvex positive lens L32, and a second sub-aperture ss2.

The fourth lens group G4 includes a joint positive lens of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42, a biconvex positive lens L43, and a negative meniscus lens with a concave surface facing the object side. It is composed of a L44 junction positive lens.

The fifth lens group G5 is composed of a biconvex positive lens L51, a biconcave negative lens L52, and a negative meniscus lens L53 with a concave surface facing the object side. Of these, the junction positive lens of the positive lens L51 and the negative lens L52 functions as the second focusing lens group F2. The image-side surface of the negative lens L52 and the image-side surface of the negative meniscus lens L53 are aspherical surfaces.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is a lens from the negative meniscus lens L23 in the second lens group G2 to the negative meniscus lens L44 in the fourth lens group G4. It is a group, and the lens group GR after the second focusing lens group is the fifth lens group G5.

Table 3 lists the values of the specifications of the variable magnification optical system according to the third embodiment.
(Table 3)
[Overall specifications]
Variable ratio = 2.201
WT
f 15.450 34.000
F.NO 2.910 2.910
2ω (°) 109.100
Ymax 18.899 21.700
TL 157.420 148.390
BF 13.738 36.025
MF1 3.797 4.236
MF2 -1.171 -2.237
fAw 45.092
fBw 35.923
fRw -71.015
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 146.1617 2.700 1.76385 48.49
2 * 17.6041 10.626
3 62.2586 2.000 1.76450 49.10
4 * 37.3724 9.332
5 -54.8177 1.700 1.45600 91.37
6 46.7428 4.900 1.90366 31.27
7 -473.8444 (D7)
8 0.0000 0.000
9 42.7469 1.200 1.96300 24.11
10 28.3019 5.700 1.58144 40.98
11 -199.8950 (D11)
12 35.6445 1.300 1.95375 32.33
13 27.0031 8.800 1.49782 82.57
14 -71.6500 (D14)
15 (S) 0.0000 5.032
16 -39.6760 1.200 1.95375 32.33
17 70.2363 0.213
18 41.9717 4.600 1.84666 23.80
19 -100.2049 1.500
20 0.0000 (D20)
21 94.6291 1.200 1.95375 32.33
22 27.9631 5.500 1.49782 82.57
23 -149.9641 0.200
24 26.9190 8.700 1.49782 82.57
25 -27.3216 1.300 1.95375 32.33
26 -47.0122 (D26)
27 44.9401 5.200 1.71736 29.57
28 -39.8168 1.400 1.85108 40.12
29 * 45.6142 (D29)
30 -25.1525 1.400 1.82098 42.50
31 * -36.5472 (D31)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = 5.13104E-06, A6 = -9.75961E-09, A8 = 1.589557E-11, A10 = -1.49213E-14
Second side κ = 0.000
A4 = 1.39883E-05, A6 = 2.12435E-08, A8 = -6.13376E-12, A10 = 1.21266E-13
Fourth side κ = 1.0000
A4 = 2.03519E-06, A6 = -3.87885E-09, A8 = -4.53903E-11, A10 = 9.19823E-14
Side 29 κ = 1.0000
A4 = 7.43097E-06, A6 = 3.66331E-08, A8 = -5.67118E-10, A10 = 4.14365E-12
Side 31 κ = 1.0000
A4 = 1.07666E-05, A6 = -4.52020E-09, A8 = 3.54595E-10, A10 = -1.67618E-12
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -23.455 0.000 0.000
2 8 38.336
2-1 (F1) 8 83.308 59.236 2.546
2-2 12 60.305 -0.125 -0.744
3 15 -122.226 1.807 4.268
4 21 51.627 0.410 0.119
5 27 -71.0145
5-1 (F2) 27 -207.910 1.032 1.100
5-2 30 -104.028 1.157 1.371
[First lens group data]
Lens focal length
L11 -26.433
L12 -126.709
L13 -55.040
L14 47.293
[Variable interval data]
Infinity close
W T W T
F 15.45000 34.00000 -0.11055 -0.23294
D0 0.00000 0.00000 115.2047 124.3997
D7 32.83524 1.51814 36.72779 6.09480
D11 6.55513 6.55513 2.65502 2.00000
D14 1.19962 6.31367 1.19962 6.31367
D20 7.79649 0.00000 7.79649 0.00000
D26 3.11247 5.79493 2.04500 3.87741
D29 6.47887 6.47887 7.56607 8.39171
D31 13.73777 36.02512 13.82147 36.34887

FIG. 8 shows various aberration values of the variable magnification optical system according to the third embodiment in the infinity object in-focus state, and FIG. 9 shows various aberration values of the variable-magnification optical system according to the third embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the third embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 4)
Example 4 will be described with reference to FIGS. 10, 11, 12, and Table 4. FIG. 10 is a diagram showing a lens configuration of the variable magnification optical system ZL (4) according to the fourth embodiment. In the variable magnification optical system ZL (4), the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the second lens group G2 having a negative refractive power are arranged in order from the object side. It is composed of three lens groups G3, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power. The image plane I is located after the fifth lens group G5. The first sub-aperture ss1 is arranged in the second lens group G2, and the aperture diaphragm S and the second sub-aperture ss2 are arranged in the third lens group G3. The first in-focus lens group F1 is composed of a part of the lens groups in the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the fifth lens group G5. Will be done.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 10 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens group (successor lens group) moves from the second lens group G2 to the fifth lens group G5 to the object side, and the first lens group G1 and the succeeding lens group By changing the interval, the shooting magnification is changed (magnification is performed). At the time of scaling, the second lens group G2 including the first focusing lens group F1 and the fifth lens group G5 including the second focusing lens group F2 move in the same direction by the same distance (movement locus is Will be the same). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 is a combination of a negative meniscus lens L11 having a convex surface facing the object side, a negative meniscus lens L12 having a convex surface facing the object side, a biconcave negative lens L13, and a biconvex positive lens L14. It consists of a negative lens. Both sides of the negative meniscus lens L11 are aspherical, and the image-side surface of the negative meniscus lens L12 is aspherical.

The second lens group G2 includes a first sub-aperture ss1, a negative meniscus lens L21 having a convex surface facing the object side, a junction positive lens of a biconvex positive lens L22, and a negative meniscus lens having a convex surface facing the object side. It is composed of an L23 and a junctioned positive lens of a biconvex positive lens L24. Of these, the junction positive lens of the negative meniscus lens L21 and the positive lens L22 functions as the first focusing lens group F1.

The third lens group G3 is composed of an aperture stop S, a biconcave negative lens L31, a biconvex positive lens L32, and a second sub-aperture ss2.

The fourth lens group G4 includes a joint positive lens of a negative meniscus lens L41 with a convex surface facing the object side and a biconvex positive lens L42, a biconvex positive lens L43, and a negative meniscus lens with a concave surface facing the object side. It is composed of a L44 junction positive lens.

The fifth lens group G5 is composed of a biconvex positive lens L51, a biconcave negative lens L52, and a negative meniscus lens L53 with a concave surface facing the object side. Of these, the junction positive lens of the positive lens L51 and the negative lens L52 functions as the second focusing lens group F2. The image-side surface of the negative lens L52 and the image-side surface of the negative meniscus lens L53 are aspherical surfaces.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is a lens group from the negative meniscus lens L23 in the second lens group G2 to the negative meniscus lens L44 in the fourth lens group G4. The lens group GR after the second focusing lens group is the fifth lens group G5.

Table 4 lists the values of the specifications of the variable magnification optical system according to the fourth embodiment.
(Table 4)
[Overall specifications]
Variable ratio = 2.201
WT
f 15.450 34.000
F.NO 2.910 2.910
2ω (°) 109.100
Ymax 19.873 21.700
TL 155.444 145.505
BF 14.459 36.100
MF1 3.585 3.939
MF2 -0.856 -2.194
fAw 45.851
fBw 36.197
fRw -78.872
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 182.9928 2.700 1.76385 48.49
2 * 17.6000 9.932
3 62.1295 2.000 1.76450 49.10
4 * 38.8027 9.134
5 -60.2019 1.700 1.45600 91.37
6 43.1768 5.000 1.90366 31.27
7 -1892.0590 (D7)
8 0.0000 0.000
9 41.6453 1.200 1.96300 24.11
10 27.0721 5.800 1.58144 40.98
11 -167.0652 (D11)
12 39.8569 1.300 1.95375 32.33
13 30.7826 7.500 1.49782 82.57
14 -61.0151 (D14)
15 0.0000 4.940
16 -37.9606 1.200 1.95375 32.33
17 76.5015 0.204
18 40.4555 4.400 1.84666 23.80
19 -123.6565 1.500
20 0.0000 (D20)
21 72.9672 1.200 1.95375 32.33
22 25.5392 5.200 1.49782 82.57
23 -692.9469 0.200
24 27.8780 8.700 1.49782 82.57
25 -24.6887 1.300 1.95375 32.33
26 -40.1293 (D26)
27 44.0613 5.200 1.71736 29.57
28 -40.6298 1.400 1.85108 40.12
29 * 46.4951 (D29)
30 -25.3720 1.400 1.82098 42.50
31 * -36.0062 (D31)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = 1111E-06, A6 = -7.07049E-09, A8 = 1.22058E-11, A10 = 1.21419E-14
Second side κ = 0.000
A4 = 8.88771E-06, A6 = 2.03824E-08, A8 = -2.28757E-11, A10 = 2.07974E-13
Fourth side κ = 1.0000
A4 = 4.90346E-06, A6 = -5.81374E-11, A8 = -4.02996E-11, A10 = 3.85740E-14
Side 29 κ = 1.0000
A4 = 7.58378E-06, A6 = 4.61458E-08, A8 = -7.11052E-10, A10 = 4.97063E-12
Side 31 κ = 1.0000
A4 = 1.22168E-05, A6 = -1.06012E-08, A8 = 4.71713E-10, A10 = -2.24069E-12
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -23.414 0.000 0.000
2 8 37.139
2-1 (F1) 8 79.731 -44.008 2.678
2-2 12 58.821 0.016 -0.674
3 15 -109.902 1.879 4.775
4 21 52.461 0.419 0.116
5 27 -78.872
5-1 (F2) 27 -245.806 1.019 1.075
5-2 3 -111.243 1.155 1.349
[First lens group data]
Lens focal length
L11 -25.675
L12 -140.400
L13 -54.857
L14 46.771
[Variable interval data]
Infinity close
W T W T
f 15.45001 34.00001 -0.10904 -0.22883
D0 0.00000 0.00000 117.1752 127.2533
D7 33.08026 1.50000 36.75391 5.79153
D11 6.28196 6.28196 2.58854 2.03546
D14 1.26244 6.38378 1.26244 6.38378
D20 8.34096 0.00000 8.34096 0.00000
D26 2.75416 5.97378 2.00611 4.08778
D29 6.15482 6.15482 6.93201 8.04153
D31 14.45898 36.09988 14.53818 36.40710

FIG. 11 shows various aberration values of the variable magnification optical system according to the fourth embodiment in the infinity object in-focus state, and FIG. 12 shows various aberration values of the variable-magnification optical system according to the fourth embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the fourth embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and also in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 5)
Example 5 will be described with reference to FIGS. 13, 14, 15, and Table 5. FIG. 13 is a diagram showing a lens configuration of the variable magnification optical system ZL (5) according to the fifth embodiment. The variable magnification optical system ZL (5) has a first lens group G1 having a negative power, a second lens group G2 having a positive power, and a first lens group G2 having a positive power, which are arranged in order from the object side. It is composed of three lens groups G3, a fourth lens group G4 having a negative power, a fifth lens group G5 having a positive power, and a sixth lens group G6 having a negative power. The image plane I is located after the sixth lens group G6. An aperture diaphragm S and a sub diaphragm ss are arranged in the fourth lens group G4. The first in-focus lens group F1 is composed of the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the fifth lens group G5.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 13 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens group (successor lens group) moves from the second lens group G2 to the sixth lens group G6 to the object side, and the first lens group G1 and the succeeding lens group By changing the interval, the shooting magnification is changed (magnification is performed). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a junction negative lens of a positive meniscus lens L13 having a convex surface facing the object side. Both sides of the negative meniscus lens L11 are aspherical.

The second lens group G2 is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22. The second lens group G2 functions as the first focusing lens group F1.

The third lens group G3 is composed of a biconvex positive lens L31 and a biconcave negative lens L32. The fourth lens group G4 is composed of an aperture diaphragm S, a biconcave negative lens L41, a biconvex positive lens L42, and a secondary diaphragm ss. The fifth lens group G5 is a junction positive lens of a biconvex positive lens L51 and a negative meniscus lens L52 with a concave surface facing the object side, and a negative meniscus lens L53 with a convex surface facing the object side and a biconvex positive lens. It is composed of a L54 junction positive lens.

The sixth lens group G6 is composed of a junction negative lens of a biconvex positive lens L61 and a biconcave negative lens L62, and a negative meniscus lens L63 with a concave surface facing the object side. Of these, the junction negative lens of the positive lens L61 and the negative lens L62 functions as the second focusing lens group F2. Both sides of the negative meniscus lens L63 are aspherical.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, the intermediate lens group GA is the lens group GR from the third lens group G3 to the fifth lens group G5, and the second focusing lens group and thereafter. The lens group of is the sixth lens group G6.

Table 5 lists the values of the specifications of the variable magnification optical system according to the fifth embodiment.
(Table 5)
[Overall specifications]
Variable ratio = 2.609
WT
f 18.549 48.400
F.NO 2.910 4.120
2ω (°) 98.952
Ymax 20.449 21.700
TL 156.976 145.902
BF 20.533 50.882
MF1 5.923 8.270
MF2 -0.524 -3.556
fAw 37.796
fBw 36.341
fRw -43.941
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 90.2223 2.800 1.74310 49.44
2 * 16.9651 14.785
3 -282.3413 2.000 1.49782 82.57
4 30.2529 7.000 1.80000 29.84
5 103.7978 (D5)
6 80.1101 1.100 1.84666 23.80
7 46.9421 4.100 1.51680 64.13
8 -63.4995 (D8)
9 34.7816 5.200 1.51680 64.13
10 -51.2859 1.100 1.65844 50.83
11 267.1556 (D11)
12 0.0000 3.149
13 -57.6080 1.200 1.83481 42.73
14 69.3506 0.200
15 45.2675 3.400 1.72825 28.38
16 -184.9091 1.500
17 0.0000 (D17)
18 68.1932 6.100 1.49782 82.57
19 -25.4228 1.100 1.95375 32.33
20 -41.8924 0.200
21 30.1508 1.100 1.95375 32.33
22 20.4880 6.300 1.49782 82.57
23 -82.9990 (D23)
24 60.5624 4.400 1.80809 22.74
25 -35.8483 1.200 1.90366 31.27
26 40.1774 (D26)
27 * -38.1852 1.600 1.82098 42.50
28 * -86.3105 (D28)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = -3.57211E-06, A6 = 4.48676E-10, A8 = 4.77136E-12, A10 = -6.03639E-15
Second side κ = 0.000
A4 = 8.11347E-06, A6 = -3.59862E-10, A8 = -1.58666E-11, A10 = 1.12811E-13
Side 27 κ = 1.0000
A4 = -2.23373E-05, A6 = 1.69704E-07, A8 = -1.19167E-09, A10 = 5.49616E-12
Side 28 κ = 1.0000
A4 = -7.84265E-07, A6 = 1.80475E-07, A8 = -9.68995E-10, A10 = 3.96145E-12
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -28.773 0.00000 0.00000
2 (F1) 6 86.248 -36.18634 2.42339
3 9 100.824 0.03055 -3.13269
4 12 -160.249 2.24066 -0.64541
5 18 37.131 0.17209 -0.15582
6 24 -43.941
6-1 (F2) 24 -92.207 1.19914 1.36024
6-2 27 -84.686 1.26135 1.61973
[First lens group data]
Lens focal length
L11 -28.583
L12 -54.773
L13 51.206
[Variable interval data]
Infinity close
W T W T
F 18.54944 48.40000 -0.12607 -0.31101
D0 0.00000 0.00000 115.7001 126.8366
D5 39.47319 1.50000 45.51103 10.34524
D8 8.04245 10.83893 2.00062 2.00000
D11 2.62907 1.75020 2.62907 1.75020
D17 8.43662 0.00000 8.43662 0.00000
D23 3.18499 6.25349 2.77969 3.26672
D26 5.14225 5.14225 5.55183 8.13586
D28 20.53328 50.88248 20.64804 51.44497

FIG. 14 shows various aberration values of the variable magnification optical system according to the fifth embodiment in the infinity object in-focus state, and FIG. 15 shows various aberration values of the variable-magnification optical system according to the fifth embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the fifth embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and also in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 6)
Example 6 will be described with reference to FIGS. 16, 17, 18, and Table 6. FIG. 16 is a diagram showing a lens configuration of the variable magnification optical system ZL (6) according to the sixth embodiment. The variable magnification optical system ZL (6) has a first lens group G1 having a negative power, a second lens group G2 having a positive power, and a first lens group G2 having a positive power, arranged in order from the object side. It is composed of three lens groups G3, a fourth lens group G4 having a negative power, a fifth lens group G5 having a positive power, and a sixth lens group G6 having a negative power. The image plane I is located after the sixth lens group G6. An aperture diaphragm S and a sub diaphragm ss are arranged in the fourth lens group G4. The first in-focus lens group F1 is composed of the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the sixth lens group G6.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 16 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens group (successor lens group) moves from the second lens group G2 to the sixth lens group G6 to the object side, and the first lens group G1 and the succeeding lens group By changing the interval, the shooting magnification is changed (magnification is performed). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a junction negative lens of a positive meniscus lens L13 having a convex surface facing the object side. Both sides of the negative meniscus lens L11 are aspherical.

The second lens group G2 is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22. The second lens group G2 functions as the first focusing lens group F1.

The third lens group G3 is composed of a biconvex positive lens L31 and a biconcave negative lens L32. The fourth lens group G4 is composed of an aperture diaphragm S, a biconcave negative lens L41, a biconvex positive lens L42, and a secondary diaphragm ss. The fifth lens group G5 is a junction positive lens of a biconvex positive lens L51 and a negative meniscus lens L52 with a concave surface facing the object side, and a negative meniscus lens L53 with a convex surface facing the object side and a biconvex positive lens. It is composed of a L54 junction positive lens.

The sixth lens group G6 is composed of a junction negative lens of a biconvex positive lens L61 and a biconcave negative lens L62, and a negative meniscus lens L63 with a concave surface facing the object side. Of these, the junction negative lens of the positive lens L61 and the negative lens L62 functions as the second focusing lens group F2. Both sides of the negative meniscus lens L63 are aspherical.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is a lens group from the third lens group G3 to the fifth lens group G5, and is after the second in-focus lens group. The lens group GR is the sixth lens group G6.

Table 6 lists the values of the specifications of the variable magnification optical system according to the sixth embodiment.
(Table 6)
[Overall specifications]
Variable ratio = 2.609
WT
f 18.550 48.400
F.NO 2.910 4.120
2ω (°) 98.950
Ymax 19.991 21.700
TL 153.169 142.360
BF 20.351 49.945
MF1 6.474 8.282
MF2 -0.810 -3.419
fAw 36.915
fBw 35.689
fRw -43.947
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 108.3788 2.800 1.74310 49.44
2 * 17.1763 13.362
3 -452.0642 2.000 1.49782 82.57
4 29.1118 7.100 1.80000 29.84
5 99.4101 (D5)
6 91.9942 1.100 1.78472 25.64
7 50.8704 3.800 1.51680 64.13
8 -60.5653 (D8)
9 32.8199 5.200 1.51680 64.13
10 -48.6591 1.100 1.66755 41.87
11 265.9956 (D11)
12 0.0000 2.687
13 -53.7450 1.200 1.83481 42.73
14 66.3134 0.200
15 43.7109 3.400 1.72825 28.38
16 -154.9801 1.500
17 0.0000 (D17)
18 87.5765 5.900 1.49782 82.57
19 -23.9396 1.100 1.95375 32.33
20 -38.0021 0.200
21 28.0976 1.100 1.95375 32.33
22 19.4681 6.200 1.49782 82.57
23 -95.1629 (D23)
24 50.2834 4.300 1.80809 22.74
25 -35.1704 1.100 1.90366 31.27
26 34.1702 (D26)
27 * -34.1324 1.600 1.82098 42.50
28 * -64.9656 (D28)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = -3.71101E-06, A6 = 1.26060E-09, A8 = 4.60876E-12, A10 = -6.89613E-15
Second side κ = 0.000
A4 = 7.33565E-06, A6 = -7.30032E-10, A8 = -1.36898E-11, A10 = 1.28740E-13
Side 27 κ = 1.0000
A4 = -2.56022E-05, A6 = 1.92542E-07, A8 = -1.42300E-09, A10 = 8.01684E-12
28th surface κ = 1.0000
A4 = -3.62729E-06, A6 = 1.98569E-07, A8 = -1.03741E-09, A10 = 4.87457E-12
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -28.822 0.00000 0.00000
2 (F1) 6 85.406 -53.24407 2.39642
3 9 95.577 0.02025 -2.83836
4 12 -155.097 2.24310 -0.75898
5 18 36.717 0.17538 -0.14799
6 24 -43.497
6-1 (F2) 24 -84.946 1.21604 1.39295
6-2 27 -89.697 1.24802 1.57795
[First lens group data]
Lens focal length
L11 -27.832
L12 -54.865
L13 49.249
[Variable interval data]
Infinity close
W T W T
F 18.55000 48.40001 -0.12247 -0.30440
D0 0.00000 0.00000 119.5188 130.3147
D5 38.74338 1.50036 45.31799 10.32723
D8 8.57407 10.83209 1.99789 2.00708
D11 2.01695 1.74095 2.01695 1.74095
D17 8.14332 0.00000 8.14332 0.00000
D23 2.96088 5.96253 2.25307 3.08659
D26 5.42939 5.42939 6.14676 8.30793
D28 20.35129 49.94512 20.44408 50.48584

FIG. 17 shows various aberration values of the variable magnification optical system according to the sixth embodiment in the infinity object in-focus state, and FIG. 18 shows various aberration values of the variable-magnification optical system according to the sixth embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the sixth embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and also in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 7)
Example 7 will be described with reference to FIGS. 19, 20, 21, and 7. FIG. 19 is a diagram showing a lens configuration of the variable magnification optical system ZL (7) according to the seventh embodiment. Variable magnification optical system ZL (7
) Are the first lens group G1 having a negative power, the second lens group G2 having a positive power, and the third lens group G3 having a positive power, which are arranged in order from the object side. It is composed of a fourth lens group G4 having a refractive power of, a fifth lens group G5 having a positive refractive power, and a sixth lens group G6 having a negative refractive power. The image plane I is located after the sixth lens group G6. An aperture diaphragm S and a sub diaphragm ss are arranged in the fourth lens group G4. The first in-focus lens group F1 is composed of the second lens group G2, and the second in-focus lens group F2 is composed of a part of the lens groups in the sixth lens group G6.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 19 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens group (successor lens group) moves from the second lens group G2 to the sixth lens group G6 to the object side, and the first lens group G1 and the succeeding lens group By changing the interval, the shooting magnification is changed (magnification is performed). When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a junction negative lens of a positive meniscus lens L13 having a convex surface facing the object side. Both sides of the negative meniscus lens L11 are aspherical.

The second lens group G2 is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22. The second lens group G2 functions as the first focusing lens group F1.

The third lens group G3 is composed of a biconvex positive lens L31 and a junction positive lens of a negative meniscus lens L32 with a concave surface facing the object side. The fourth lens group G4 is composed of an aperture diaphragm S, a biconcave negative lens L41, a biconvex positive lens L42, and a secondary diaphragm ss. The fifth lens group G5 is a junction positive lens of a biconvex positive lens L51 and a negative meniscus lens L52 with a concave surface facing the object side, and a negative meniscus lens L53 with a convex surface facing the object side and a biconvex positive lens. It is composed of a L54 junction positive lens.

The sixth lens group G6 is composed of a junction negative lens of a biconvex positive lens L61 and a biconcave negative lens L62, and a negative meniscus lens L63 with a concave surface facing the object side. Of these, the junction negative lens of the positive lens L61 and the negative lens L62 functions as the second focusing lens group F2. Both sides of the negative meniscus lens L63 are aspherical.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is a lens group from the third lens group G3 to the fifth lens group G5, and is after the second in-focus lens group. The lens group GR is the sixth lens group G6.

Table 7 lists the values of the specifications of the variable magnification optical system according to the seventh embodiment.
(Table 7)
[Overall specifications]
Variable ratio = 2.933
WT
f 16.500 48.400
F.NO 4.120 4.120
2ω (°) 105.504
Ymax 18.820 21.700
TL 156.081 146.333
BF 17.312 53.242
MF1 4.885 6.965
MF2 -0.399 -3.058
fAw 37.470
fBw 35.351
fRw -45.510
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 134.1598 2.800 1.74310 49.44
2 * 17.3629 14.016
3 -207.6212 2.000 1.49782 82.57
4 29.0503 6.600 1.80000 29.84
5 97.9008 (D5)
6 108.9553 1.100 1.78472 25.64
7 58.4582 3.700 1.51680 64.13
8 -61.2766 (D8)
9 37.1209 5.400 1.51680 64.13
10 -45.0995 1.100 1.66755 41.87
11 -1370.1266 (D11)
12 0.0000 2.672
13 -60.0593 1.200 1.83481 42.73
14 70.3031 0.200
15 41.0334 3.500 1.72825 28.38
16 -503.4893 1.500
17 0.0000 (D17)
18 57.5208 6.200 1.49782 82.57
19 -26.7338 1.100 1.95375 32.33
20 -48.6295 0.200
21 29.6649 1.100 1.95375 32.33
22 20.5335 6.400 1.49782 82.57
23 -77.8504 (D23)
24 52.0903 4.600 1.80809 22.74
25 -36.2422 1.100 1.90366 31.27
26 37.7038 (D26)
27 * -29.1452 1.600 1.82098 42.50
28 * -52.4528 (D28)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = -1.70329E-06, A6 = -4.31330E-09, A8 = 1.34611E-11, A10 = -1.36560E-14
Second side κ = 0.000
A4 = 9.12318E-06, A6 = 1.23871E-09, A8 = -5.72137E-11, A10 = 2.49570E-13
Side 27 κ = 1.0000
A4 = -3.31284E-05, A6 = 1.22380E-07, A8 = 2.11071E-09, A10 = -2.29278E-11
Side 28 κ = 1.0000
A4 = -9.98288E-06, A6 = 1.77118E-07, A8 = 1.12908E-09, A10 = -1.30549E-11
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -26.499 0.00000 0.00000
2 (F2) 6 91.061 16.86926 2.08615
3 9 89.248 -0.06542 -4.61760
4 12 -156.468 2.27422 -0.46520
5 18 37.326 0.17425 -0.18415
6 24 -45.510
6-1 (F1) 24 -101.406 1.15313 1.32490
6-2 27 -82.444 1.23474 1.67054
[First lens group data]
Lens focal length
L11 -27.116
L12 -51.049
L13 49.524
[Variable interval data]
Infinity close
W T W T
F 16.50000 48.40001 -0.11390 -0.31928
D0 0.00000 0.00000 116.64620 126.37030
D5 39.81885 1.56641 44.78663 9.12142
D8 8.35182 9.55705 3.37035 2.00000
D11 1.50000 2.62405 1.50000 2.62405
D17 11.73118 0.00000 11.73118 0.00000
D23 3.52789 5.50426 3.22544 3.03834
D26 5.75143 5.75143 6.06613 8.22322
D28 17.31220 53.24168 17.39668 53.82834

FIG. 20 shows various aberration values of the variable magnification optical system according to the seventh embodiment in the infinity object in-focus state, and FIG. 21 shows various aberration values of the variable-magnification optical system according to the seventh embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the seventh embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and in the close-range object focusing state. It can be seen that also has excellent imaging performance.

(Example 8)
Example 8 will be described with reference to FIGS. 22, 23, 24 and Table 8. FIG. 22 is a diagram showing a lens configuration of the variable magnification optical system ZL (8) according to the eighth embodiment. In the variable magnification optical system ZL (8), the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the second lens group G2 having a positive refractive power arranged in order from the object side. The 3 lens group G3, the 4th lens group G4 having a negative refractive power, the 5th lens group G5 having a positive refractive power, the 6th lens group G6 having a negative refractive power, and the negative refractive power. It is composed of a seventh lens group G7 having the lens group G7. The image plane I is located after the seventh lens group G7. An aperture diaphragm S and a sub diaphragm ss are arranged in the fourth lens group G4. In this embodiment, the second lens group has the function of the first focusing lens group, and the sixth lens group G6 has the function of the second focusing lens group F2.

Each lens group moves along the trajectory indicated by the arrow in the lower part of FIG. 22 when the variable magnification optical system changes the magnification from the wide-angle end state (W) to the telephoto end state (T). The first lens group G1 moves to the image plane side, the lens groups (following lens groups) from the second lens group G2 to the seventh lens group G7 move to the object side, and the first lens group G1 and the succeeding lens group The shooting magnification is changed (magnification is performed) by changing the interval between the lenses. When focusing from an infinity object to a short-range object, the first focusing lens group F1 is on the image plane side and the second focusing lens group F2 is on the object side, as shown by the arrow in the upper part of FIG. , Move each.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side, a negative lens L12 having a biconcave shape, and a positive meniscus lens L13 having a convex surface facing the object side.
The second lens group G2 is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22. The second lens group G2 functions as the first focusing lens group F1. Both sides of the negative meniscus lens L11 are aspherical.
The third lens group G3 is composed of a biconvex positive lens L31 and a junction positive lens of a negative meniscus lens L32 with a concave surface facing the object side.
The fourth lens group G4 is composed of an aperture diaphragm S, a biconcave negative lens L41, a biconvex positive lens L42, and a secondary diaphragm ss.
The fifth lens group G5 is a junction positive lens of a biconvex positive lens L51 and a negative meniscus lens L52 with a concave surface facing the object side, and a negative meniscus lens L53 with a convex surface facing the object side and a biconvex positive lens. It is composed of a junction positive lens of the lens L54.
The sixth lens group G6 is composed of a junction negative lens of a biconvex positive lens L61 and a biconcave negative lens L62. The sixth lens group G6 functions as a second focusing lens group F2.
The seventh lens group G7 is composed of a negative meniscus lens L71 with a concave surface facing the object side. Both sides of the negative meniscus lens L71 are aspherical.

In this embodiment, the first lens group G1 corresponds to the preceding lens group, and the intermediate lens group GA is a lens group from the third lens group G3 to the fifth lens group G5, and is after the second in-focus lens group. The lens group GR is a sixth lens group G6 and a seventh lens group G7.

Table 8 lists the values of the specifications of the variable magnification optical system according to the eighth embodiment.
(Table 8)
[Overall specifications]
Variable ratio = 2.933
WT
f 16.500 48.400
F.NO 4.120 4.120
2ω (°) 105.504
Ymax 18.872 21.700
TL 160.040 148.673
BF 17.332 52.943
MF1 5.206 6.968
MF2 -0.467 -3.076
fAw 38.918
fBw 36.708
fRw -47.139
[Lens specifications]
Surface number RD nd νd
Object surface ∞
1 * 117.2640 2.800 1.743104 49.44
2 * 17.3212 13.690
3 -156.3592 2.000 1.593190 67.90
4 39.9621 0.342
5 37.5152 6.000 1.805180 25.45
6 219.2739 (D6)
7 134.0709 1.100 1.808090 22.74
8 65.0269 3.700 1.516800 64.13
9 -55.2510 (D9)
10 36.8869 5.400 1.516800 64.13
11 -46.9141 1.100 1.667550 41.87
12 -800.1555 (D12)
13 0.0000 2.756
14 -55.1029 1.200 1.834810 42.73
15 69.9489 0.200
16 41.8100 3.500 1.728250 28.38
17 -271.2095 1.500
18 0.0000 (D18)
19 66.4403 6.400 1.497820 82.57
20 -25.1331 1.100 1.953750 32.33
21 -43.7484 0.200
22 32.7210 1.100 1.953750 32.33
23 22.3913 6.400 1.497820 82.57
24 -73.9478 (D24)
25 47.6278 4.600 1.808090 22.74
26 -43.4729 1.100 1.903660 31.27
27 35.3715 (D27)
28 * -26.9922 1.600 1.851080 40.12
29 * -44.6033 (D29)
Image plane ∞
[Aspherical data]
First side κ = 1.0000
A4 = -2.77685E-06, A6 = -1.993715E-09, A8 = 9.77420E-12, A10 = -1.04746E-14
Second side κ = 0.000
A4 = 7.71325E-06, A6 = -1.61526E-09, A8 = -3.27497E-11, A10 = 1.80698E-13
28th surface κ = 1.0000
A4 = -3.46903E-05, A6 = 2.09403E-07, A8 = -3.45825E-10, A10 = -1.51984E-12
Side 29 κ = 1.0000
A4 = -1.44962E-05, A6 = 2.30556E-07, A8 = -4.70958E-10, A10 = -2.52537E-13
[Lens group data]
Group starting surface Focal length Magnification (∞ ・ W) Magnification (∞ ・ T)
1 1 -26.869 0.00000 0.00000
2 (F1) 7 92.184 31.98911 2.11262
3 10 85.150 -0.03062 -3.15125
4 13 -148.380 2.15636 -0.76347
5 19 38.525 0.20623 -0.16413
6 (F2) 25 -106.810 1.14232 1.30169
7 28 -83.826 1.23402 1.65883
[First lens group data]
Lens focal length
L11 -27.680
L12 -53.452
L13 55.393
[Variable interval data]
Infinity close
W T W T
F 16.50000 48.39999 -0.11689 -0.32517
D0 0.00000 0.00000 112.64110 124.11340
D5 42.25411 1.50098 47.54374 9.08570
D8 9.08559 9.59007 3.78313 2.00000
D11 2.76237 5.31731 2.76237 5.31731
D17 11.72943 0.00000 11.72943 0.00000
D23 2.87290 5.69317 2.50191 3.23900
D26 6.21551 5.84159 6.59892 8.30977
D28 17.33241 52.94259 17.41638 53.55044

FIG. 23 shows various aberration values of the variable magnification optical system according to the eighth embodiment in the infinity object in-focus state, and FIG. 24 shows various aberration values of the variable-magnification optical system according to the eighth embodiment in the close-range object in-focus state. Are shown respectively. In these figures, (A) shows various aberration values in the wide-angle end state, and (B) shows various aberration values in the telephoto end state. From each aberration diagram, the variable magnification optical system according to the eighth embodiment can satisfactorily correct various aberrations over the entire range from the wide-angle end state to the telephoto end state, and also in the close-range object focusing state. It can be seen that also has excellent imaging performance.

The list of conditional expressions and the corresponding values of the conditional expressions of each embodiment are shown below.
[List of conditional expressions]
(1) MF2w / MF1w
(2) (-f1) / fw
(3) (-f1) / ft
(4) fL1 / f1
(5) f1 × Σ (1 / (flk × νdLk))
(6) (L1R2-L1R1) / (L1R2 + L1R1)
(7) (LeR2-LeR1) / (LeR2 + LeR1)
(8) 2ωw
(9) fw / (-fRw)
(10) STLw / TLw
(11) STLt / TLt
(12) BFw / TLw
(13) fF1 / (-fF2)
(14) 1 / βF1w
(15) 1 / βF2w
(16) {βF1W + (1 / βF1W)} ^-2
(17) {βF2W + (1 / βF2W)} ^-2
(18) fF1 / fBw
(19) fRw / fF2
(20) fw / fAw
(21) dF1w / TLw
(22) dF2w / TLw
(23) MF2t / MF1t
(24) (1-βF2w ² ) × βRw ² × MF2w
(25) ｜ βF2w / βF2t ｜

[Conditional expression correspondence value]
Example 1 Example 2 Example 3 Example 4 Example 5 Example 5 Example 6
(1) -0.255 -0.161 -0.308 -0.239 -0.089 -0.125
(2) 1.415 1.411 1.518 1.515 1.551 1.554
(3) 0.687 0.685 0.690 0.689 0.594 0.595
(4) 1.081 1.086 1.127 1.097 0.993 0.966
(5) 0.0134 0.0118 0.0109 0.0109 0.0079 0.0077
(6) -0.719 -0.743 -0.785 -0.825 -0.683 -0.726
(7) 0.184 0.186 0.185 0.173 0.387 0.311
(8) 105.504 105.248 109.100 109.100 98.952 98.950
(9) 0.179 0.178 0.218 0.196 0.422 0.422
(10) 0.434 0.452 0.436 0.441 0.438 0.440
(11) 0.573 0.592 0.578 0.585 0.642 0.645
(12) 0.095 0.104 0.087 0.093 0.131 0.133
(13) 0.407 0.452 0.401 0.324 0.935 1.005
(14) 0.2281 -0.0044 0.0169 -0.0227 -0.0276 -0.0188
(15) 0.9343 0.9123 0.9685 0.9818 0.8339 0.8223
(16) 0.04703 0.00002 0.00028 0.00052 0.00076 0.00035
(17) 0.24885 0.24791 0.24974 0.24992 0.24193 0.24067
(18) 2.737 2.140 2.319 2.203 2.373 2.393
(19) 0.365 0.558 0.342 0.321 0.477 0.517
(20) 0.377 0.404 0.343 0.337 0.491 0.503
(21) 0.390 0.391 0.407 0.409 0.421 0.418
(22) 0.817 0.803 0.821 0.816 0.791 0.786
(23) -0.381 -0.419 -0.528 -0.557 -0.430 -0.413
(24) 0.208 0.163 0.104 0.043 0.365 0.604
(25) 0.958 0.939 0.939 0.947 0.882 0.873

Example 7 Example 8
(1) -0.082 -0.090
(2) 1.606 1.628
(3) 0.548 0.555
(4) 1.023 1.030
(5) 0.0081 0.0080
(6) -0.771 -0.743
(7) 0.286 0.246
(8) 105.504 105.504
(9) 0.363 0.350
(10) 0.447 0.436
(11) 0.655 0.647
(12) 0.111 0.108
(13) 0.898 0.863
(14) 0.7822 0.0313
(15) 0.8672 0.8754
(16) 0.23551 0.00098
(17) 0.24499 0.24563
(18) 2.576 2.511
(19) 0.449 0.441
(20) 0.440 0.424
(21) 0.418 0.419
(22) 0.805 0.869
(23) -0.439 -0.441
(24) 0.201 0.217
(25) 0.870 0.878

The invention of the present application is not limited to the above embodiment, and can be appropriately modified as long as the optical performance specified by the description of each claim is not impaired.

For example, in the above embodiment, the variable magnification optical system having a 5-group, 6-group, and 7-group configuration is shown, but the variable magnification optical system having other group configurations (for example, the most object side or the most image plane side of the variable magnification optical system) A lens or a lens group is added to the configuration, etc.). Here, the lens group refers to a portion having at least one lens separated by an air interval that changes at the time of magnification change or focusing.

Regarding the aperture diaphragm, although the aperture diaphragm is arranged in the third lens group or the fourth lens group in each of the above embodiments, the role of the aperture diaphragm is substituted by the lens frame without providing the member as the aperture diaphragm. Can be considered. Further, in each of the above embodiments, one or two sub-diaphragms are arranged, but the sub-diaphragm may not be provided.

Further, the lens surface may be spherical, flat or aspherical. The spherical or flat lens surface facilitates lens processing and assembly adjustment, can prevent deterioration of optical performance due to errors in lens processing and assembly adjustment, and further deteriorates depiction performance even if the image surface shifts. It has the advantage of being less. The aspherical lens surface may be an aspherical surface obtained by grinding, a glass-molded aspherical surface obtained 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. Each lens surface may be provided with an antireflection film having high transmittance in a wide wavelength range in order to reduce flare and ghost and achieve high contrast optical performance.

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

Claims (27)

It has a leading lens group having a negative refractive power and a succeeding lens group arranged in order from the object side.
At the time of scaling, the distance between the preceding lens group and the succeeding lens group changes,
The subsequent lens group includes a first focusing lens group and a second focusing lens group arranged on the image plane side of the first focusing lens group.
The first focusing lens group has a positive refractive power and moves toward the image plane along the optical axis when focusing from an infinity object to a short-distance object.
The second focusing lens group has a negative refractive power and moves toward the object along the optical axis when focusing from an infinity object to a short-distance object.
A variable magnification optical system that satisfies the following conditional expression.
-1.00 <MF2w / MF1w <0.00
However,
MF1w: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the wide-angle end state MF2w: Close distance from the infinity object of the second focusing lens group in the wide-angle end state Amount of movement when focusing on an object (The amount of movement represents the movement toward the image plane as a positive value.) The variable magnification optical system according to claim 1, which satisfies the following conditional expression.
1.00 <(-f1) / fw <2.00
However,
f1: Focal length of the preceding lens group fw: Focal length when the variable magnification optical system is in focus at an infinity object in the wide-angle end state. The variable magnification optical system according to claim 1 or 2, which satisfies the following conditional expression.
0.00 <(-f1) / ft <1.00
However,
f1: Focal length of the preceding lens group ft: Focal length when the variable magnification optical system is in focus at an infinity object in the telephoto end state. The variable magnification optical system according to any one of claims 1 to 3, which satisfies the following conditional expression.
0.50 <fL1 / f1 <1.50
However,
fL1: Focal length of the first lens from the object side among the lenses constituting the preceding lens group f1: Focal length of the preceding lens group The variable magnification optical system according to any one of claims 1 to 4, which satisfies the following conditional expression.
−0.020 <f1 × Σ (1 / (flk × νdLk)) <0.020
However,
f1: Focal length of the preceding lens group fLk: Focal length of the kth lens from the object side among the lenses constituting the preceding lens group νdLk: The kth lens from the object side among the lenses constituting the preceding lens group Abbe number The variable magnification optical system according to any one of claims 1 to 5, which satisfies the following conditional expression.
-1.50 <(L1R2-L1R1) / (L1R2 + L1R1) <0.00
However,
L1R1: Radius of curvature of the surface of the lens placed closest to the object side in the variable magnification optical system L1R2: Radius of curvature of the surface of the lens placed closest to the object side on the image plane side The variable magnification optical system according to any one of claims 1 to 6, which satisfies the following conditional expression.
0.00 <(LeR2-LeR1) / (LeR2 + LeR1) <1.00
However,
LeR1: Radius of curvature of the surface of the lens placed closest to the image plane side in the variable magnification optical system LeR2: Radius of curvature of the surface of the lens placed closest to the image plane side The variable magnification optical system according to any one of claims 1 to 7, which satisfies the following conditional expression.
80 ° <2ωw <130 °
However,
2ωw: Full angle of view when focusing an object at infinity in the variable magnification optical system at the wide-angle end state The variable magnification optical system according to any one of claims 1 to 8, which satisfies the following conditional expression.
0.05 <fw / (-fRw) <0.60
However,
fw: Focal length of the variable magnification optical system when focusing on an infinity object in the wide-angle end state fRw: Focal length of the lens group after the second focusing lens group in the wide-angle end state when focusing on an infinity object The variable magnification optical system according to any one of claims 1 to 9, which has an aperture diaphragm arranged in the subsequent lens group and satisfies the following conditional expression.
0.35 <STLw / TLw <0.55
However,
STRw: Distance on the optical axis from the aperture stop when focusing on an infinity object in the wide-angle end state TLw: Total length of the variable magnification optical system when focusing on an infinity object in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 10, which satisfies the following conditional expression.
0.50 <STLt / TLt <0.75
However,
STRt: Distance on the optical axis from the aperture stop when focusing on an infinity object in the telephoto end state TLt: Overall length of the variable magnification optical system when focusing on an infinity object in the telephoto end state The variable magnification optical system according to any one of claims 1 to 11, which satisfies the following conditional expression.
0.05 <BFw / TLw <0.20
However,
BFw: Back focus of the variable magnification optical system when focusing on an infinity object in the wide-angle end state TLw: Overall length of the variable magnification optical system when focusing on an infinity object in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 12, which satisfies the following conditional expression.
0.00 <fF1 / (-fF2) <2.00
However,
fF1: Focal length of the first focusing lens group fF2: Focal length of the second focusing lens group The variable magnification optical system according to any one of claims 1 to 13, which satisfies the following conditional expression.
1.00 <1 / βF1w <2.00
However,
βF1: Lateral magnification when focusing on an infinity object of the first focusing lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 14, which satisfies the following conditional expression.
0.10 <1 / βF2w <1.00
However,
βF2: Lateral magnification when focusing on an infinity object of the second focusing lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 15, which satisfies the following conditional expression.
{βF1w + (1 / βF1w)} ^-2 <0.250
However,
βF1: Lateral magnification when focusing on an infinity object of the first focusing 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.
{βF2w + (1 / βF2w)} ^-2 <0.250
However,
βF2: Lateral magnification when focusing on an infinity object of the second focusing lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 17, which satisfies the following conditional expression.
1.50 <fF1 / fBw <3.50
However,
fF1: Focal length of the first focusing lens group fBw: Combined focal length of the subsequent lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 18, which satisfies the following conditional expression.
0.10 <fRw / fF2 <0.80
However,
fRw: Focal length at the time of focusing an object at infinity of the lens group after the second focusing lens group in the wide-angle end state fF2: Focal length of the second focusing lens group An intermediate lens group including at least one lens is provided between the first focusing lens group and the second focusing lens group.
The variable magnification optical system according to any one of claims 1 to 19, which satisfies the following conditional expression.
0.20 <fw / fAw <0.80
However,
fw: Focal length when the variable magnification optical system is in focus at infinity in the wide-angle end state fAw: Composite focal length of the intermediate lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 20, which satisfies the following conditional expression.
0.30 <dF1w / TLw <0.50
However,
dF1w: The most in the first focusing lens group from the object side surface of the lens arranged on the object side most in the variable magnification optical system when focusing on an infinity object in the wide-angle end state. Distance on the optical axis to the object-side surface of the lens placed on the object-side TLw: Total length of the variable-magnification optical system when the variable-magnification optical system is in focus at the wide-angle end state. The variable magnification optical system according to any one of claims 1 to 21, which satisfies the following conditional expression.
0.60 <dF2w / TLw <0.90
However,
dF2w: The most in the second focusing lens group from the object side surface of the lens arranged on the object side most in the variable magnification optical system when focusing on an infinity object in the wide-angle end state. Distance on the optical axis to the object-side surface of the lens placed on the object-side TLw: Total length of the variable-magnification optical system when the variable-magnification optical system is in focus at the wide-angle end state. The variable magnification optical system according to any one of claims 1 to 22, which satisfies the following conditional expression.
-1.00 <MF2t / MF1t <0.00
However,
MF1t: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the telephoto end state MF2t: Close distance from the infinity object of the second focusing lens group in the telephoto end state Amount of movement when focusing on an object (The amount of movement represents the movement toward the image plane as a positive value.) The variable magnification optical system according to any one of claims 1 to 23, which satisfies the following conditional expression.
0.00 <(1-βF2w ² ) × βRw ² × MF2w <1.00
However,
βF2w: Lateral magnification when the second in-focus lens group is in focus at the wide-angle end state βRw: Total magnification of the lens group after the second in-focus lens group in the wide-angle end state MF2w: The above in the wide-angle end state Amount of movement during focusing from an infinity object to a close-range object in the second focusing lens group The variable magnification optical system according to any one of claims 1 to 24, which satisfies the following conditional expression.
0.50 << | βF2w / βF2t | <5.00
However,
βF2w: Lateral magnification when the second in-focus lens group is in focus at the wide-angle end state βF2t: Lateral magnification when the second in-focus lens group is in focus at the telephoto end state An optical device equipped with the variable magnification optical system according to any one of claims 1 to 25. It has a leading lens group and a trailing lens group having a negative refractive power arranged side by side from the object side.
At the time of scaling, the distance between the preceding lens group and the succeeding lens group changes,
The subsequent lens group includes a first focusing lens group and a second focusing lens group arranged on the image plane side of the first focusing lens group.
The first focusing lens group has a positive refractive power and moves toward the image plane along the optical axis when focusing from an infinity object to a short-distance object.
The second focusing lens group has a negative refractive power and moves toward the object along the optical axis when focusing from an infinity object to a short-distance object.
A method for manufacturing a variable magnification optical system in which each lens group is configured and arranged in a lens barrel so as to satisfy the following conditional expression.
-1.00 <MF2w / MF1w <0.00
However,
MF1w: Amount of movement when focusing from an infinity object of the first focusing lens group to a close-range object in the wide-angle end state MF2w: Close distance from the infinity object of the second focusing lens group in the wide-angle end state Amount of movement when focusing on an object (The amount of movement represents the movement toward the image plane as a positive value.)

Images