JP7103417B2 - Magnification optical system, optical equipment, and manufacturing method of variable magnification optics - Google Patents

Description

The present invention relates to variable magnification optical systems, optical instruments, and methods for manufacturing variable magnification optical systems.

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

Patent No. 5781244

The present invention
From the object side, the first lens group having a negative refractive power, the second lens group having a positive refractive power, the third lens group having a negative refractive power, and the fourth lens having a positive refractive power. Have a group and
At the time of scaling, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the fourth lens group change. The distance from the lens group changes,
The second lens group is composed of a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power in order from the object side.
Image blur is corrected by moving the second b lens group so as to include a component in the direction orthogonal to the optical axis.
This is a variable magnification optical system in which the third lens group moves in the optical axis direction during focusing.

In addition, the present invention
From the object side, the first lens group having a negative refractive power, the second lens group having a positive refractive power, the third lens group having a negative refractive power, and the fourth lens having a positive refractive power. A method for manufacturing a variable magnification optical system having a group.
At the time of scaling, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the fourth lens group change. It is configured so that the distance from the lens group changes,
The second lens group is composed of a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power in order from the object side. Configure to
The second b lens group is configured to correct image blur by moving it so as to include a component in a direction orthogonal to the optical axis.
This is a method for manufacturing a variable magnification optical system that is configured so that the third lens group moves in the optical axis direction at the time of focusing.

FIG. 1 is a cross-sectional view of the variable magnification optical system according to the first embodiment in a wide-angle end state. 2A and 2B are aberration diagrams of the variable magnification optical system according to the first embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 3 is a cross-sectional view of the variable magnification optical system according to the second embodiment in the wide-angle end state. 4A and 4B are aberration diagrams of the variable magnification optical system according to the second embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 5 is a cross-sectional view of the variable magnification optical system according to the third embodiment in the wide-angle end state. 6A and 6B are aberration diagrams of the variable magnification optical system according to the third embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 7 is a cross-sectional view of the variable magnification optical system according to the fourth embodiment in the wide-angle end state. 8A and 8B are aberration diagrams of the variable magnification optical system according to the fourth embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 9 is a cross-sectional view of the variable magnification optical system according to the fifth embodiment in the wide-angle end state. 10A and 10B are aberration diagrams of the variable magnification optical system according to the fifth embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 11 is a cross-sectional view of the variable magnification optical system according to the sixth embodiment in the wide-angle end state. 12A and 12B are aberration diagrams of the variable magnification optical system according to the sixth embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 13 is a cross-sectional view of the variable magnification optical system according to the seventh embodiment in a wide-angle end state. 14A and 14B are aberration diagrams of the variable magnification optical system according to the seventh embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 15 is a cross-sectional view of the variable magnification optical system according to the eighth embodiment in the wide-angle end state. 16A and 16B are aberration diagrams of the variable magnification optical system according to the eighth embodiment in the wide-angle end state and the telephoto end state, respectively. FIG. 17 is a diagram showing a configuration of a camera provided with a variable magnification optical system. FIG. 18 is a flow chart showing an outline of a method for manufacturing a variable magnification optical system.

Hereinafter, a method for manufacturing a variable magnification optical system, an optical device, and a variable magnification optical system according to an embodiment of the present invention will be described.
The variable magnification optical system of the present embodiment includes a first lens group having a negative refractive force, a second lens group having a positive refractive force, and a third lens group having a negative refractive force in order from the object side. It has a fourth lens group having a positive refractive force, and at the time of scaling, the distance between the first lens group and the second lens group changes, and the second lens group and the third lens group The distance between the lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group changes. It is composed of a second b lens group having the same refractive power and a second c lens group having a negative refractive power.

The variable magnification optical system of the present embodiment can realize variable magnification by such a configuration, can satisfactorily correct various aberrations, and can realize miniaturization.

Further, under such a configuration, the variable magnification optical system of the present embodiment corrects image blur by moving the second b lens group so as to include a component in a direction orthogonal to the optical axis. As a result, image blurring due to camera shake can be minimized. Further, the influence on the peripheral image plane including the eccentric coma generated when correcting the image blur is affected by the second a lens group arranged on the front side of the second b lens group and the second c lens arranged on the rear side. It can be corrected well in groups.

Further, under such a configuration, in the variable magnification optical system of the present embodiment, the third lens group moves in the optical axis direction at the time of focusing. As a result, the drive mechanism of the third lens group, which is the focusing lens group, can be miniaturized, and good optical performance can be obtained from the infinity object focusing state to the short-distance object focusing state.

With the above configuration, the variable magnification optical system of the present embodiment has high optical performance capable of satisfactorily suppressing image blurring and satisfactorily correcting various aberrations, and is a miniaturized variable magnification optical system. It can be realized.

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

The conditional expression (1) is a conditional expression for defining an appropriate range for the ratio of the focal length of the second b lens group, which is an anti-vibration lens group, to the focal length of the entire variable magnification optical system in the telephoto end state. Is. By satisfying the conditional expression (1), the variable magnification optical system of the present embodiment can be miniaturized and coma aberration can be satisfactorily corrected.

If the corresponding value of the conditional expression (1) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the refractive power of the second b lens group becomes weak and the shift amount at the time of vibration isolation increases, so that the size can be reduced. It is not preferable in terms of surface. In addition, coma aberration and curvature of field are insufficiently corrected. By setting the upper limit value of the conditional expression (1) to 1.680, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (1) are set to 1.650, 1.630, 1.600, 1.580, 1.550, 1.530, 1. It is preferably 500, 1.480, and more preferably 1.450.

On the other hand, if the corresponding value of the conditional expression (1) of the variable magnification optical system of the present embodiment is less than the lower limit value, the refractive power of the second b lens group becomes strong and the position control at the time of vibration isolation becomes difficult, which is not preferable. In addition, it becomes difficult to correct eccentric coma and coma aberration. By setting the lower limit value of the conditional expression (1) to 0.220, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (1) are set to 0.240, 0.260, 0.280, 0.300, 0.320, 0.340, 0. It is preferably 360, 0.380, and more preferably 0.400.

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (2).
(2) 0.150 <f21 / ft <2.000
however,
f21: Focal length of the second a lens group ft: Focal length of the entire variable magnification optical system in the telephoto end state

The conditional expression (2) is a conditional expression that defines an appropriate ratio between the focal length of the second a lens group and the focal length of the entire variable magnification optical system in the telephoto end state. The variable magnification optical system of the present embodiment can satisfactorily correct spherical aberration and coma aberration by satisfying the conditional equation (2).

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

On the other hand, when the corresponding value of the conditional expression (2) of the variable magnification optical system of the present embodiment is less than the lower limit value, the refractive power of the second a lens group becomes stronger, and spherical aberration and coma aberration can be satisfactorily corrected. It will disappear. By setting the lower limit value of the conditional expression (2) to 0.200, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (2) are set to 0.220, 0.240, 0.260, 0.280, 0.300, 0.320, 0. It is preferably 340, 0.350, and more preferably 0.360.

Further, in the variable magnification optical system of the present embodiment, it is desirable that the second a lens group is composed of a junction lens. As a result, the variable magnification optical system of the present embodiment can satisfactorily correct chromatic aberration. In particular, by arranging the second a lens group in the second lens group near the aperture, it is effective in correcting axial chromatic aberration.

Further, in the variable magnification optical system of the present embodiment, it is desirable that the second b lens group is composed of a junction lens. As a result, the variable magnification optical system of the present embodiment can satisfactorily correct chromatic aberration. In particular, by arranging the second b lens group in the second lens group near the aperture, it is effective in correcting axial chromatic aberration.

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (3).
(3) 1.00 <(-fγw) <2.00
however,
fγw: Ratio of the amount of movement of the image plane to the amount of movement of the third lens group in the wide-angle end state

The conditional expression (3) is a conditional expression that defines the ratio of the amount of movement of the image plane to the amount of movement of the third lens group, which is the focusing lens group, in the wide-angle end state. By satisfying the conditional equation (3), the variable magnification optical system of the present embodiment is miniaturized while securing the necessary focus stroke, and further, from infinity object focusing to short-distance object focusing. It is possible to satisfactorily correct the curvature of field variation of.

When the corresponding value of the conditional expression (3) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the refractive power of the third lens group, which is the focusing lens group, becomes strong, and it becomes difficult to control the focusing position. Not preferable. In addition, the curvature of field becomes large, making correction difficult. By setting the upper limit value of the conditional expression (3) to 1.90, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (3) is set to 1.80, 1.75, 1.70, 1.68, 1.65, 1.62, 1. It is preferably 60, 1.58, and more preferably 1.55.

On the other hand, when the corresponding value of the conditional expression (3) of the variable magnification optical system of the present embodiment is less than the lower limit value, the refractive power of the third lens group, which is the focusing lens group, becomes weak, and the third lens group It is not preferable in terms of miniaturization because the amount of movement increases. In addition, the curvature of field cannot be corrected satisfactorily. By setting the lower limit value of the conditional expression (3) to 1.05, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (3) are set to 1.10, 1.15, 1.18, 1.20, 1.21 and further 1.22. Is preferable.

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (4).
(4) 0.05 <f21 / f22 <3.00
however,
f21: Focal length of the second a lens group f22: Focal length of the second b lens group

The conditional expression (4) is a conditional expression for defining an appropriate ratio between the focal length of the second a lens group and the focal length of the second b lens group. By satisfying the conditional equation (4), the variable magnification optical system of the present embodiment has an appropriate power arrangement between the junction lens of the second a lens group and the junction lens of the second b lens group, and covers the entire zoom range. Chromatic aberration can be satisfactorily corrected. In particular, by arranging the bonded lens of the second a lens group and the bonded lens of the second b lens group in the second lens group near the diaphragm, it is effective in correcting axial chromatic aberration.

When the corresponding value of the conditional expression (4) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the refractive power of the second a lens group becomes weaker and the refractive power of the second b lens group becomes stronger. This is not preferable because the balance of chromatic aberration correction is lost. In particular, it becomes impossible to satisfactorily correct the axial chromatic aberration on the telephoto side. By setting the upper limit value of the conditional expression (4) to 2.70, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (4) is set to 2.50, 2.20, 2.00, 1.95, 1.90, 1.85, 1. It is preferably 82, 1.80, and more preferably 1.78.

On the other hand, when the corresponding value of the conditional expression (4) of the variable magnification optical system of the present embodiment is less than the lower limit value, the refractive power of the second a lens group becomes stronger and the refractive power of the second b lens group becomes weaker. It is not preferable because the balance of chromatic aberration correction at the time of fluctuation is lost. In particular, it becomes impossible to satisfactorily correct the axial chromatic aberration on the wide-angle side. By setting the lower limit value of the conditional expression (4) to 0.08, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (4) are set to 0.10, 0.13, 0.15, 0.18, 0.20, 0.23, 0. It is preferably 24, 0.25, and more preferably 0.26.

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (5).
(5) 0.50 <(-f3) / fw <3.00
however,
f3: Focal length of the third lens group fw: Focal length of the entire variable magnification optical system in the wide-angle end state

The conditional expression (5) is a conditional expression that defines the ratio between the focal length of the third lens group, which is the focusing lens group, and the focal length of the entire variable magnification optical system in the wide-angle end state. By satisfying the conditional equation (5), the variable magnification optical system of the present embodiment secures the necessary focus stroke, reduces the size of the drive mechanism and structure of the focusing lens group, and further reduces the object at infinity. Fluctuations in curvature of field can be satisfactorily corrected from the focused state to the focused state of a short-range object, especially in the focal length range on the wide-angle side.

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

On the other hand, when the corresponding value of the conditional expression (5) of the variable magnification optical system of the present embodiment is less than the lower limit value, the refractive power of the third lens group, which is the focusing lens group, becomes stronger, and the position control of the focusing lens group is performed. It is not preferable because it becomes difficult. In addition, the curvature of field becomes large, making correction difficult. By setting the lower limit value of the conditional expression (5) to 0.60, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (5) are set to 0.70, 0.80, 0.90, 0.95, 1.00, 1.05, 1. It is preferably 10, 1.15, and more preferably 1.20.

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

The conditional expression (6) is a conditional expression for defining an appropriate length on the optical axis of the second lens group. By satisfying the conditional expression (6), the variable magnification optical system of the present embodiment can be miniaturized and can satisfactorily correct spherical aberration and coma.

When the corresponding value of the conditional expression (6) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the second lens group becomes thicker. In this case, the refractive power of the second lens group is weakened, the number of lenses constituting the second lens group is increased, or the thickness of the lenses constituting the second lens group is increased, resulting in an increase in size. It is not preferable because it ends up. By setting the upper limit value of the conditional expression (6) to 0.450, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (6) are set to 0.400, 0.380, 0.350, 0.330, 0.300, 0.280, 0. It is preferably 260, 0.250, and more preferably 0.230.

On the other hand, when the corresponding value of the conditional expression (6) of the variable magnification optical system of the present embodiment is less than the lower limit value, the second lens group becomes thin. In this case, the refractive power of the second lens group becomes stronger, or the number of lenses constituting the second lens group decreases. As a result, spherical aberration and coma cannot be satisfactorily corrected. By setting the lower limit value of the conditional expression (6) to 0.130, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (6) are set to 0.140, 0.150, 0.160, 0.165, 0.170, 0.175, 0. It is preferably 180, 0.185, and more preferably 0.190.

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

The conditional expression (7) is a conditional expression for defining an appropriate length on the optical axis of the fourth lens group. By satisfying the conditional expression (7), the variable magnification optical system of the present embodiment can be miniaturized and can satisfactorily correct the curvature of field when the zoom fluctuates.

When the corresponding value of the conditional expression (7) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the fourth lens group becomes thicker. In this case, the refractive power of the 4th lens group is weakened, the number of lenses constituting the 4th lens group is increased, or the thickness of the lenses constituting the 4th lens group is increased, resulting in an increase in size. It is not preferable because it ends up. By setting the upper limit value of the conditional expression (7) to 0.180, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (7) are set to 0.150, 0.130, 0.110, 0.100, 0.095, 0.092, 0. It is preferably 090, 0.088, and more preferably 0.085.

On the other hand, when the corresponding value of the conditional expression (7) of the variable magnification optical system of the present embodiment is less than the lower limit value, the fourth lens group becomes thin. In this case, the refractive power of the fourth lens group becomes stronger, or the number of lenses constituting the fourth lens group decreases. As a result, the curvature of field cannot be corrected satisfactorily. By setting the lower limit value of the conditional expression (7) to 0.025, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (7) are set to 0.030, 0.035, 0.040, 0.043, 0.045, 0.048, 0. It is preferably 050, 0.053, and further 0.055.

Further, in the variable magnification optical system of the present embodiment, it is desirable that the third lens group comprises one lens component and satisfies the following conditional expression (8).
(8) -20.00 <R2f3 / R1f3 <-1.00
however,
R1f3: Radius of curvature of the lens surface on the most object side of the lens component R2f3: Radius of curvature of the lens surface on the most image side of the lens component

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

When the corresponding value of the conditional expression (8) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the shape of the lens component has a sharp curvature of field on the image plane side, and flare is likely to occur on the image plane. turn into. By setting the upper limit value of the conditional expression (8) to −1.05, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (8) are set to -1.10, -1.15, -1.20, -1.30, -1.40,-. It is preferably 1.50, -1.60, -1.70, -1.80.

On the other hand, if the corresponding value of the conditional expression (8) of the variable magnification optical system of the present embodiment is less than the lower limit value, the effect of correcting curvature of field is reduced. By setting the lower limit value of the conditional expression (8) to -19.00, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (8) are set to -18.00, -17.00, -16.00, -15.00, -14.00,-. It is preferably 13.00, -12.00, -11.00, -10.00.

Further, in the variable magnification optical system of the present embodiment, it is desirable that the third lens group has at least one aspherical surface. As a result, the drive mechanism and structure of the third lens group, which is the in-focus lens group, are downsized, and the variation of the curvature of field from the infinity object in-focus state to the short-distance object in-focus state is effectively corrected. be able to.

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (9).
(9) -16.00 <(-f23) /ft <5.00
however,
f23: Focal length of the second c lens group ft: Focal length of the entire variable magnification optical system in the telephoto end state

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

If the corresponding value of the conditional expression (9) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the refractive power of the second c lens group becomes weak, and coma aberration and spherical aberration become insufficiently corrected. By setting the upper limit value of the conditional expression (9) to 4.60, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit of the conditional expression (9) is set to 4.30, 4.00, 3.50, 3.00, 2.80, 2.30, 2. It is preferably 00, 1.80, and more preferably 1.50.

On the other hand, when the corresponding value of the conditional expression (9) of the variable magnification optical system of the present embodiment is less than the lower limit value, the refractive power of the second c lens group becomes strong, and coma aberration and spherical aberration are overcorrected. By setting the lower limit value of the conditional expression (9) to 0.10, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the lower limit values of the conditional expression (9) are set to 0.15, 0.25, 0.25, 0.30, 0.35, 0.40, 0. It is preferably 45, 0.48, 0.50, and more preferably 0.53.

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (10).
(10) 50.0 ° <2ω <120.0 °
however,
2ω: Full angle of view of the variable magnification optical system in the wide-angle end state

The conditional expression (10) is a condition that defines the optimum value of the angle of view. By satisfying the conditional expression (10), the variable magnification optical system of the present embodiment can be miniaturized and various aberrations can be satisfactorily corrected.

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

Further, it is desirable that the variable magnification optical system of the present embodiment satisfies the following conditional expression (11).
(11) 0.20 <Bfa / fw <0.90
however,
Bfa: Air-equivalent back focus of the entire variable-magnification optical system in the wide-angle end state fw: Focal length of the entire variable-magnification optical system in the wide-angle end state

The conditional expression (11) is a conditional expression that defines the ratio between the air-equivalent back focus of the entire variable-magnification optical system in the wide-angle end state and the focal length of the entire variable-magnification optical system in the wide-angle end state. .. By satisfying the conditional equation (11), the variable magnification optical system of the present embodiment can be miniaturized and various aberrations can be satisfactorily corrected.

If the corresponding value of the conditional expression (11) of the variable magnification optical system of the present embodiment exceeds the upper limit value, the back focus becomes long, which is not preferable in terms of miniaturization. By setting the upper limit value of the conditional expression (11) to 0.85, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (11) are set to 0.80, 0.78, 0.75, 0.73, 0.70, 0.68, 0. It is preferably 67, 0.66, and more preferably 0.65.

On the other hand, if the corresponding value of the conditional expression (11) of the variable magnification optical system of the present embodiment is less than the lower limit value, the back focus becomes short and there is a concern of interference with the camera mechanism. By setting the lower limit value of the conditional expression (11) to 0.25, the effect of the present embodiment can be made more reliable. Further, in order to further ensure the effect of the present embodiment, the upper limit values of the conditional expression (11) are set to 0.30, 0.35, 0.40, 0.42, 0.45, 0.48, 0. It is preferably 50, 0.52, and more preferably 0.55.

The optical device of this embodiment has a variable magnification optical system having the above-described configuration. As a result, it is possible to realize an optical device having high optical performance capable of satisfactorily suppressing image blurring and satisfactorily correcting various aberrations, and being miniaturized.

The method for manufacturing the variable magnification optical system of the present embodiment is as follows, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a negative refractive power. It is a method of manufacturing a variable magnification optical system having a lens group and a fourth lens group having a positive refractive force, and the distance between the first lens group and the second lens group changes at the time of magnification change. The distance between the second lens group and the third lens group changes, and the distance between the third lens group and the fourth lens group changes, and the second lens group is on the object side. The second b lens group is composed of a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power in this order. Is configured to correct image blur by moving the lens so as to include a component in a direction orthogonal to the optical axis, and the third lens group is configured to move in the optical axis direction at the time of focusing. This is a method for manufacturing an optical system.

As a result, it is possible to manufacture a variable magnification optical system having high optical performance capable of satisfactorily suppressing image blurring and satisfactorily correcting various aberrations and achieving miniaturization.

Hereinafter, the variable magnification optical system according to the numerical embodiment of the present embodiment will be described with reference to the accompanying drawings.
(First Example)
FIG. 1 is a cross-sectional view of the variable magnification optical system according to the first embodiment in a wide-angle end state. The arrows in FIG. 1, FIG. 5, FIG. 5, FIG. 7, FIG. 9, FIG. 11, and FIG. It shows the movement trajectory of the group.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c is composed of a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

Table 1 below lists the specifications of the variable magnification optical system according to this embodiment.
In Table 1, f indicates the focal length, and BF indicates the back focus, that is, the distance on the optical axis from the lens surface on the image side to the image surface I.
In [plane data], m is the order of the optical planes counted from the object side, r is the refractive index, d is the plane spacing (distance between the nth plane (n is an integer) and the n + 1 plane), and νd is the d line (d line). The Abbe number with respect to the wavelength 587.6 nm, nd indicates the refractive index with respect to the d line (wavelength 587.6 nm), and ng indicates the refractive index with respect to the g line (wavelength 435.8 nm). Further, OP indicates an object surface, dn (n is an integer) indicates a variable surface interval, S indicates an aperture stop, and I indicates an image plane. The radius of curvature r = ∞ indicates a plane. The description of the refractive index nd of air = 1.00000 is omitted. When the lens surface is aspherical, "*" is added to the surface number and the radius of curvature r indicates the near-axis radius of curvature.

[Aspherical surface data] shows the aspherical surface coefficient and the conical constant when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
S (y) = (y ² / R) / [1 + {1-κ (y / R) ² } ^1/2 ]
＋ C4y ⁴ ＋ C6y ⁶ ＋ C8y ⁸ ＋ C 10y ¹⁰
Here, y is the height in the direction perpendicular to the optical axis, and S (y) is the sag amount, which is the distance along the optical axis direction from the tangent plane of the apex of the aspherical surface at the height y to the aspherical surface, κ. Let be the conical constant, C4, C6, C8, C10, C12, C14 be the aspherical coefficient, and R be the near-axis radius of curvature, which is the radius of curvature of the reference sphere. In addition, "En" (n: integer) indicates "x10- ⁿ ", for example, "1.234E-05" indicates "1.234 × ^10-5 ". The second-order aspherical coefficient C2 is 0, and the description is omitted.

In [various data], f is the focal length of the entire optical system, FNo is the F number, 2ω is the angle of view (unit is “°”), Ymax is the maximum image height, and TL is the variable magnification optical system according to this embodiment. The total length of the lens, that is, the distance from the first surface to the image plane I on the optical axis, and BF indicates the back focus, that is, the distance on the optical axis from the lens surface on the most image side to the image plane I. W indicates a wide-angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state.

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

Here, "mm" is generally used as the unit of the focal length f, the radius of curvature r and other lengths listed in Table 1. However, the optical system is not limited to this because the same optical performance can be obtained even if the optical system is proportionally expanded or decreased.
The reference numerals in Table 1 described above shall be used in the same manner in the tables of the respective examples described later.

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

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

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

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

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

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

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

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

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

2A and 2B are aberration diagrams of the variable magnification optical system according to the first embodiment in the wide-angle end state and the telephoto end state, respectively.

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

From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

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

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a bonded positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a positive meniscus lens L24 having a convex surface facing the object side.
The second c lens group G2c is composed of a biconcave negative lens L25. The negative lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the object image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

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

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

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

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

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

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

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

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

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

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

4A and 4B are aberration diagrams of the variable magnification optical system according to the second embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

(Third Example)
FIG. 5 is a cross-sectional view of the variable magnification optical system according to the third embodiment in the wide-angle end state.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c is composed of a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

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

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

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

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

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

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

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

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

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

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

6A and 6B are aberration diagrams of the variable magnification optical system according to the third embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

(Fourth Example)
FIG. 7 is a cross-sectional view of the variable magnification optical system according to the fourth embodiment in the wide-angle end state.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a positive refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c is composed of a positive meniscus lens L25 having a convex surface facing the object side. The positive meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. Then, the third lens group G3 and the fourth lens group G4 move along the optical axis. Specifically, the first lens group G1 moves to the image side and then moves to the object side, the second lens group G2 moves to the object side, the third lens group G3 moves to the object side, and the fourth lens group G1 moves to the object side. The lens group G4 moves to the object side and then to the image side.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

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

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

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

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

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

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

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

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

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

[Conditional expression correspondence value]
(1) f22 / ft = 1.442
(2) f21 / ft = 0.483
(3) (-fγw) = 1.260
(4) f21 / f22 = 0.335
(5) (-f3) / fw = 1.464
(6) G2 / TLt = 0.211
(7) G4 / TLt = 0.056
(8) R2f3 / R1f3 = -6.736
(9) (-f23) /ft=-15.561
(10) 2ω = 87.610
(11) Bfa / fw = 0.580

8A and 8B are aberration diagrams of the variable magnification optical system according to the fourth embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

(Fifth Example)
FIG. 9 is a cross-sectional view of the variable magnification optical system according to the fifth embodiment in the wide-angle end state.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c is composed of a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

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

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

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

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

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

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

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

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

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

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

10A and 10B are aberration diagrams of the variable magnification optical system according to the fifth embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

(6th Example)
FIG. 11 is a cross-sectional view of the variable magnification optical system according to the sixth embodiment in the wide-angle end state.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a junction positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a biconvex positive lens L22. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c is composed of a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

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

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

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

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

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

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

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

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

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

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

12A and 12B are aberration diagrams of the variable magnification optical system according to the sixth embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

(7th Example)
FIG. 13 is a cross-sectional view of the variable magnification optical system according to the seventh embodiment in a wide-angle end state.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c includes a negative meniscus lens L25 having a convex surface facing the object side and a negative meniscus lens L26 having a convex surface facing the object side. The negative meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

Table 7 below lists the specifications of the variable magnification optical system according to this embodiment.

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

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

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

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

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

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

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

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

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

14A and 14B are aberration diagrams of the variable magnification optical system according to the seventh embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

(8th Example)
FIG. 15 is a cross-sectional view of the variable magnification optical system according to the eighth embodiment in the wide-angle end state.
In the variable magnification optical system according to the present embodiment, the first lens group G1 having a negative refractive power, the second lens group G2 having a positive refractive power, and the third lens group G2 having a negative refractive power are arranged in this order from the object side. It is composed of a lens group G3 and a fourth lens group G4 having a positive refractive power.

The first lens group G1 is composed of a negative meniscus lens L11 having a convex surface facing the object side and a positive meniscus lens L12 having a convex surface facing the object side in order from the object side. The negative meniscus lens L11 is an aspherical lens in which a resin layer provided on the glass lens surface on the image side is formed in an aspherical shape.

The second lens group G2 has a second a lens group G2a having a positive refractive power, an aperture aperture S, a second b lens group G2b having a positive refractive power, and a second lens group G2b having a negative refractive power in order from the object side. It is composed of a 2c lens group G2c.

The second a lens group G2a is composed of a bonded positive lens of a negative meniscus lens L21 having a convex surface facing the object side and a positive meniscus lens L22 having a convex surface facing the object side. The negative meniscus lens L21 is an aspherical lens having an aspherical shape on the lens surface on the object side.
The second b lens group G2b is composed of a junction positive lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.
The second c lens group G2c is composed of a negative meniscus lens L25 having a convex surface facing the object side. The negative meniscus lens L25 is an aspherical lens having an aspherical shape on the lens surface on the object side.

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

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

Based on the above configuration, in the variable magnification optical system according to the present embodiment, the distance between the first lens group G1 and the second lens group G2 is reduced when the magnification is changed from the wide-angle end state to the telescopic end state. The first lens group G1 and the second lens group G2 so that the distance between the second lens group G2 and the third lens group G3 increases and the distance between the third lens group G3 and the fourth lens group G4 increases. And the third lens group G3 move along the optical axis. Specifically, the first lens group G1 moves to the image side once, then moves to the object side, the second lens group G2 moves to the object side, and the third lens group G3 moves to the object side. At the time of scaling, the position of the fourth lens group G4 is fixed with respect to the image plane I.

The variable magnification optical system according to this embodiment focuses the third lens group G3 from an infinity object to a short-distance object by moving it toward the image side along the optical axis.

In the variable magnification optical system according to the present embodiment, the second b lens group G2b is moved as an anti-vibration lens group so as to include a component in a direction orthogonal to the optical axis, thereby correcting the image plane when image blurring occurs, that is, anti-vibration. I do.

Table 7 below lists the specifications of the variable magnification optical system according to this embodiment.

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

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

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

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

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

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

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

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

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

16A and 16B are aberration diagrams of the variable magnification optical system according to the eighth embodiment in the wide-angle end state and the telephoto end state, respectively.
From each aberration diagram, it can be seen that the variable magnification optical system according to the present embodiment satisfactorily corrects various aberrations from the wide-angle end state to the telephoto end state and has excellent imaging performance.

According to each of the above embodiments, the variable magnification optical system has high optical performance capable of satisfactorily suppressing image blurring and satisfactorily correcting various aberrations from the wide-angle end state to the telephoto end state, and is miniaturized. Can be realized.

It should be noted that each of the above examples shows a specific example of the present invention, and the present invention is not limited thereto. The following contents can be appropriately adopted as long as the optical performance of the variable magnification optical system of the present embodiment is not impaired.

As a numerical example of the variable magnification optical system of the present embodiment, a four-group configuration is shown, but the present embodiment is not limited to this, and other group configurations (for example, five groups, etc.) of the variable magnification optical system are configured. You can also do it. Specifically, a lens or a lens group may be added to the most object side or the most image side of the variable magnification optical system of each of the above embodiments. Alternatively, a lens or a lens group may be added between adjacent lens groups.

Further, in each of the above embodiments, the third lens is a focusing lens group. Such a focusing lens group can also be applied to autofocus, and is also suitable for driving by a motor for autofocus, for example, an ultrasonic motor, a stepping motor, a VCM motor, or the like.

Further, in each of the above embodiments, the second b lens group is used as the anti-vibration lens group, but the present invention is not limited to this, and the entire or a part of any of the lens groups is used as the anti-vibration lens group and is perpendicular to the optical axis. It is also possible to provide vibration isolation by moving the lens so as to include a directional component or rotating (swinging) the lens in the in-plane direction including the optical axis.

Further, the aperture diaphragm of the variable magnification optical system of each of the above embodiments may be configured such that a lens frame substitutes the role of the aperture diaphragm without providing a member as the aperture diaphragm.

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

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

Next, the camera provided with the variable magnification optical system of the present embodiment will be described with reference to FIG.
FIG. 17 is a diagram showing a configuration of a camera provided with the variable magnification optical system of the present embodiment.
As shown in FIG. 17, the camera 1 is a lens-interchangeable mirrorless camera provided with the variable magnification optical system according to the first embodiment as the photographing lens 2.

In the camera 1, the light from an object (subject) (not shown) is collected by the photographing lens 2 and passed through an OLPF (Optical low pass filter) (not shown) on the imaging surface of the imaging unit 3. Form a subject image. Then, the subject image is photoelectrically converted by the photoelectric conversion element provided in the imaging unit 3, and the image of the subject is generated. This image is displayed on the EVF (Electronic viewfinder) 4 provided in the camera 1. This allows the photographer to observe the subject via the EVF4.
Further, when the photographer presses the release button (not shown), the image of the subject generated by the imaging unit 3 is stored in the memory (not shown). In this way, the photographer can shoot the subject with the camera 1.

Here, the variable magnification optical system according to the first embodiment mounted on the camera 1 as the photographing lens 2 satisfactorily suppresses image blurring and improves various aberrations from the wide-angle end state to the telephoto end state as described above. It has high optical performance that can be corrected to, and has been miniaturized. That is, the present camera 1 has high optical performance capable of satisfactorily suppressing image blurring and satisfactorily correcting various aberrations, and can realize miniaturization. Even if a camera equipped with the variable magnification optical system according to the second to eighth embodiments is configured as the photographing lens 2, the same effect as that of the camera 1 can be obtained. Further, even when the single-lens reflex type camera having a quick return mirror and observing the subject by the finder optical system is equipped with the variable magnification optical system according to each of the above embodiments, the same effect as that of the camera 1 can be obtained. can.

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

Step S1: At the time of scaling, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the third lens group change. It is configured so that the distance from the fourth lens group changes.
Step S2: The second lens group includes a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a secondc lens group having a negative refractive power in order from the object side. It is configured to consist of.
Step S3: The second b lens group is configured to correct the image blur by moving the second b lens group so as to include a component in a direction orthogonal to the optical axis.
Step S4: The third lens group is configured to move in the optical axis direction during focusing.

According to the method for manufacturing the variable magnification optical system of the present embodiment, the variable magnification optical system has high optical performance capable of satisfactorily suppressing image blurring and satisfactorily correcting various aberrations, and is miniaturized. The system can be manufactured.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G2a 2nd lens group
G2b 2b lens group G2c 2c lens group S Aperture aperture I Image plane 1 Camera 2 Shooting lens

Claims (17)

From the object side, the first lens group having a negative refractive power, the second lens group having a positive refractive power, the third lens group having a negative refractive power, and the fourth lens having a positive refractive power. Consists of a group
At the time of scaling, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the fourth lens group change. The distance from the lens group changes,
The second lens group is composed of a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power in order from the object side.
Image blur is corrected by moving the second b lens group so as to include a component in the direction orthogonal to the optical axis.
At the time of focusing, the third lens group moves in the optical axis direction,
A variable magnification optical system that satisfies the following conditional expression .
0.05 <f21 / f22 <3.00
however,
f21: Focal length of the second a lens group
f22: Focal length of the second b lens group From the object side, the first lens group having a negative refractive power, the second lens group having a positive refractive power, the third lens group having a negative refractive power, and the fourth lens having a positive refractive power. Consists of a group
At the time of scaling, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the third lens group changes, and the third lens group and the fourth lens group change. The distance from the lens group changes,
The second lens group is composed of a second a lens group having a positive refractive power, a second b lens group having a positive refractive power, and a second c lens group having a negative refractive power in order from the object side.
Image blur is corrected by moving the second b lens group so as to include a component in the direction orthogonal to the optical axis.
At the time of focusing, the third lens group moves in the optical axis direction,
A variable magnification optical system that satisfies the following conditional expression .
0.150 <f21 / ft <1.000
however,
f21: Focal length of the second a lens group
ft: Focal length of the entire variable magnification optical system in the telephoto end state The variable magnification optical system according to claim 1 , which satisfies the following conditional expression.
0.150 <f21 / ft <2.000
however,
f21: Focal length of the second a lens group ft: Focal length of the entire variable magnification optical system in the telephoto end state The variable magnification optical system according to claim 2 , which satisfies the following conditional expression.
0.05 <f21 / f22 <3.00
however,
f21: Focal length of the second a lens group f22: Focal length of the second b lens group The variable magnification optical system according to any one of claims 1 to 4, which satisfies the following conditional expression.
0.200 <f22 / ft <1.700
however,
f22: Focal length of the second b lens group ft: Focal length of the entire variable magnification optical system in the telephoto end state The variable magnification optical system according to any one of claims 1 to 5 , wherein the second a lens group comprises a junction lens. The variable magnification optical system according to any one of claims 1 to 6 , wherein the second b lens group comprises a junction lens. The variable magnification optical system according to any one of claims 1 to 7 , which satisfies the following conditional expression.
1.00 <(-fγw) <2.00
however,
fγw: Ratio of the amount of movement of the image plane to the amount of movement of the third lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 8 , which satisfies the following conditional expression.
0.50 <(-f3) / fw <3.00
however,
f3: Focal length of the third lens group fw: Focal length of the entire variable magnification optical system in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 9 , which satisfies the following conditional expression.
0.100 <G2 / TLt <0.500
however,
G2: Length on the optical axis of the second lens group TLt: Length on the optical axis of the entire variable magnification optical system in the telephoto end state The variable magnification optical system according to any one of claims 1 to 10 , which satisfies the following conditional expression.
0.020 <G4 / TLt <0.200
however,
G4: Length on the optical axis of the fourth lens group TLt: Length on the optical axis of the entire variable magnification optical system in the telephoto end state The variable magnification optical system according to any one of claims 1 to 11 , wherein the third lens group comprises one lens component and satisfies the following conditional expression.
-20.00 <R2f3 / R1f3 <-1.00
however,
R1f3: Radius of curvature of the lens surface on the most object side of the lens component R2f3: Radius of curvature of the lens surface on the most image side of the lens component The variable magnification optical system according to any one of claims 1 to 12 , wherein the third lens group has at least one aspherical surface. The variable magnification optical system according to any one of claims 1 to 13 , which satisfies the following conditional expression.
-16.00 <(-f23) /ft <5.00
however,
f23: Focal length of the second c lens group ft: Focal length of the entire variable magnification optical system in the telephoto end state The variable magnification optical system according to any one of claims 1 to 14 , which satisfies the following conditional expression.
50.0 ° <2ω <120.0 °
however,
2ω: Full angle of view of the variable magnification optical system 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.
0.20 <Bfa / fw <0.90
however,
Bfa: Air-equivalent back focus of the entire variable-magnification optical system in the wide-angle end state fw: Focal length of the entire variable-magnification optical system in the wide-angle end state An optical device provided with the variable magnification optical system according to any one of claims 1 to 16 .

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