JP6919812B2 - Variable magnification optical system and optical equipment - Google Patents

Description

The present invention relates to variable magnification optical systems and optical instruments.

Various zoom methods are known for variable magnification optical systems such as moving image variable magnification optical systems and single-lens reflex cameras. There are various focus methods, and a type having a focus group in the first lens group is known as a structurally simple method (see, for example, Patent Document 1). However, Patent Document 1 has a problem that further improvement in optical performance is required.

Japanese Unexamined Patent Publication No. 2004-145304

The variable magnification optical system according to the first aspect of the present invention has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power in order from the object side. It has a third lens group and a fourth lens group having a positive refractive force, and upon scaling, the second lens group and the third lens group move in the optical axis direction, and the first lens group is The fourth lens has a first A lens group having a positive refractive force, a first B lens group having a negative refractive force, and a first C lens group having a positive refractive force in this order from the object side. The group includes a front group, which is a vibration-proof group that moves so that at least a part of the lens has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive force, in order from the object side. Upon focusing, the first B lens group moves in the optical axis direction and satisfies the condition of the following equation.
0.30 <f1 / ft <0.75
0.708 ≤ f4 / ft <3.00
However,
f1: Focal length of the first lens group
f4: Focal length of the fourth lens group ft: Focal length of the entire system in the telephoto end state

The variable magnification optical system according to the second aspect of the present invention has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power in order from the object side. It has a third lens group and a fourth lens group having a positive refractive force, and upon scaling, the second lens group and the third lens group move in the optical axis direction, and the first lens The group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in this order from the object side. The 1B lens group consists of a bonded lens in which a positive lens and a negative lens are joined, and the fourth lens group moves in order from the object side so that at least a part of the lens has a displacement component in a direction orthogonal to the optical axis. It has a front group which is an anti-vibration group and a rear group which has a positive refractive force, and is characterized in that the first B lens group moves in the optical axis direction at the time of focusing and satisfies the condition of the following equation. And.
0.30 <f1 / ft <0.75
However,
f1: Focal length of the first lens group
ft: Focal length of the entire system at the telephoto end

The variable magnification optical system according to the third aspect of the present invention has a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive refractive power in order from the object side. It has a third lens group and a fourth lens group having a positive refractive force, and upon scaling, the second lens group and the third lens group move in the optical axis direction, and the first lens The group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in this order from the object side. The four lens groups include a front group, which is a vibration-proof group that moves so that at least a part of the lens group has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive force, in order from the object side. The air spacing between the front group and the rear group of the fourth lens group is the largest air spacing among the air spacings in the fourth lens group, and the first B lens group has an optical axis when focusing. It moves in a direction and satisfies the condition of the following equation.
0.30 <f1 / ft <0.75
However,
f1: Focal length of the first lens group
ft: Focal length of the entire system at the telephoto end

The variable magnification optical system according to the fourth aspect of the present invention has a first lens group having a positive refractive force, a second lens group having a negative refractive force, and a positive refractive force in order from the object side. It has a third lens group and a fourth lens group having a positive refractive force, and upon scaling, the second lens group and the third lens group move in the optical axis direction, and the first lens The group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in this order from the object side. The four lens groups include a front group, which is a vibration-proof group that moves so that at least a part of the lens group has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive force, in order from the object side. However, upon focusing, the first B lens group moves in the optical axis direction and satisfies the condition of the following equation.
0.30 <f1 / ft <0.75
0.15 <Dc / Σ4 <0.50
However,
f1: Focal length of the first lens group
ft: Focal length of the entire system at the telephoto end
Dc: The distance between the front group and the rear group of the fourth lens group on the optical axis.
Σ4: Distance on the optical axis from the lens surface on the most object side to the lens surface on the image side of the fourth lens group.

The variable magnification optical system according to the fifth aspect of the present invention has a first lens group having a positive refractive force, a second lens group having a negative refractive force, and a positive refractive force in order from the object side. It has a third lens group and a fourth lens group having a positive refractive force, and upon scaling, the second lens group and the third lens group move in the optical axis direction, and the first lens The group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in this order from the object side. The four lens groups include a front group, which is a vibration-proof group that moves so that at least a part of the lens group has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive force, in order from the object side. Then, upon focusing, the first B lens group moves in the optical axis direction, satisfying the conditions of the following equation.
0.30 <f1 / ft <0.75
However,
f1: Focal length of the first lens group
ft: Focal length of the entire system at the telephoto end
The first lens group has a positive lens, and the positive lens on the most object side of the first lens group satisfies the condition of the following equation.
ΔθgF2 ≧ 0.045
0.17 <f1C / fg1
However,
ΔθgF2: Abnormal dispersibility of the medium of the positive lens on the most object side of the first lens group
f1C: Focal length of the first C lens group of the first lens group
fg1: Focal length of the positive lens on the most object side of the first lens group
Here, ΔθgF2 = θgF2- (0.648327-0.0018024 × νd2).
However,
θgF2≡ (ng-nF) / (nF-nC): Partial dispersion ratio of the medium of the positive lens on the most object side of the first lens group.
ng: Refractive index of the medium of the positive lens on the most object side of the first lens group with respect to the g line.
nF: Refractive index of the medium of the positive lens on the most object side of the first lens group with respect to the F line.
nC: Refractive index of the medium of the positive lens on the most object side of the first lens group with respect to the C line.
νd: Abbe number with respect to the d-line of the medium of the positive lens on the most object side of the first lens group.

It is sectional drawing which shows the lens structure in the infinity focusing state and the wide-angle end state when the magnification conversion optical group of the variable magnification optical system which concerns on 1st Example is not inserted. It is a diagram of various aberrations of the infinity focusing state when the magnification conversion optical group of the variable magnification optical system according to the first embodiment is not inserted, (a) shows a wide-angle end state, and (b) is an intermediate focal length state. (C) shows the telephoto end state. It is sectional drawing which shows the lens structure in the infinity focusing state and the wide-angle end state at the time of inserting the magnification conversion optical group of the variable magnification optical system which concerns on 1st Example. It is a diagram of various aberrations of the infinity focusing state at the time of inserting the magnification conversion optical group of the variable magnification optical system according to the first embodiment, in which (a) shows a wide-angle end state and (b) shows a telephoto end state. .. It is sectional drawing which shows the lens structure in the infinity focusing state and the wide-angle end state when the magnification conversion optical group of the variable magnification optical system which concerns on 2nd Example is not inserted. It is a diagram of various aberrations of the infinity focusing state when the magnification conversion optical group of the variable magnification optical system according to the second embodiment is not inserted, (a) shows a wide-angle end state, and (b) is an intermediate focal length state. (C) shows the telephoto end state. It is sectional drawing of the camera which carries the said variable magnification optical system. It is a flowchart for demonstrating the manufacturing method of the variable magnification optical system.

Hereinafter, preferred embodiments will be described with reference to the drawings. As shown in FIG. 1, in the variable magnification optical system ZL according to the present embodiment, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and so on. It is configured to have a third lens group G3 having a positive refractive power and a fourth lens group G4 having a positive refractive power. Further, in the variable magnification optical system ZL according to the present embodiment, the second lens group G2 and the third lens group G3 move in the optical axis direction at the time of magnification change. Further, in the variable magnification optical system ZL according to the present embodiment, it is desirable that the first lens group G1 is fixed to the image plane at the time of magnification change. With such a configuration, the lens driving mechanism can be simplified, and fluctuations of various aberrations such as spherical aberration and curvature of field at the time of scaling can be reduced, which is preferable. Further, in the variable magnification optical system ZL according to the present embodiment, it is desirable that the fourth lens group G4 is fixed to the image plane at the time of magnification change. With such a configuration, the lens driving mechanism can be simplified, and fluctuations of various aberrations such as spherical aberration and curvature of field at the time of scaling can be reduced, which is preferable.

Further, in the variable magnification optical system ZL according to the present embodiment, the first lens group G1 has a first A lens group G1A having a positive refractive power and a first B lens group G1B having a negative refractive power in this order from the object side. And a first C lens group G1C having a positive refractive power, and upon focusing, the first B lens group G1B is set as a focusing group, and this focusing group moves in the optical axis direction. Here, it is desirable that the first B lens group G1B is composed of one lens component, particularly a bonded lens in which a positive lens and a negative lens are bonded. Such a configuration is preferable because various aberrations such as spherical aberration and chromatic aberration can be reduced.

Further, in the variable magnification optical system ZL according to the present embodiment, the fourth lens group G4 is a vibration isolation group that moves in order from the object side so that at least a part of the lens group has a displacement component in a direction orthogonal to the optical axis. It has a front group G4F (in FIG. 1, the fourth B lens group G4B is a vibration isolation group) and a rear group G4R having a positive refractive power. In the variable magnification optical system ZL according to the present embodiment, as shown in FIG. 1, the front group GF is composed of the 4A lens group G4A, the 4B lens group G4B, and the 4C lens group G4C, and the rear group G4R. Is composed of a fourth D lens group G4D. Such a configuration is preferable because it is possible to reduce fluctuations of various aberrations such as spherical aberration and curvature of field during scaling.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (1) shown below.

0.30 <f1 / ft <0.75 (1)
However,
f1: Focal length of the first lens group G1 ft: Focal length of the entire system in the telephoto end state

The conditional equation (1) defines the focal length of the first lens group G1 having a positive refractive power with respect to the focal length of the variable magnification optical system ZL according to the present embodiment in the telephoto end state. By strongly using the refractive power of the first lens group G1, light rays can pass through like a superfocal length lens. By satisfying this conditional expression (1), the luminous flux diameter after the second lens group G2 can be reduced. Further, if the focusing group is provided in the first lens group G1 as described above, the internal focusing type cam becomes unnecessary and the lens barrel can be made thinner.

If the upper limit of the conditional expression (1) is exceeded, the amount of the off-axis luminous flux is reduced and the imaging performance is deteriorated in wave optics, which is not preferable. In order to ensure the effect of the conditional expression (1), the upper limit of the conditional expression (1) is set to 0.73, and further set to 0.70, 0.67, 0.63, 0.60. Is more desirable.

Further, if it is less than the lower limit of the conditional expression (1), it becomes difficult to correct the distortion, and further, it becomes difficult to correct the fluctuation of various aberrations at the time of focusing from an infinite distance to a close distance, which is not preferable. In order to ensure the effect of the conditional expression (1), the lower limit of the conditional expression (1) is set to 0.33, and further 0.37, 0.40, 0.43, 0.47, 0. It is more desirable to set it to .50 and 0.53.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (2) shown below.

0.42 <f4 / ft <3.00 (2)
However,
f4: Focal length of the 4th lens group G4 ft: Focal length of the entire system in the telephoto end state

The conditional expression (2) defines the focal length of the fourth lens group G4 with respect to the focal length of the entire system at the time of focusing at infinity in the telephoto end state.

If the upper limit of the conditional expression (2) is exceeded, the focal length of the fourth lens group G4 becomes small, and it becomes difficult to correct various aberrations at the time of vibration isolation, particularly the eccentric coma and the image plane. Further, as will be described later, when the magnification conversion optical group Gx is inserted, its various aberrations are further enlarged, which is not preferable. In order to ensure the effect of the conditional expression (2), the upper limit of the conditional expression (2) is set to 2.90, and further 2.80, 2.50, 2.00, 1.80, 1 It is more desirable to set it to .50, 1.30, 1.00, 0.80.

If it falls below the lower limit of the conditional expression (2), the focal length from the first lens group G1 to the third lens group G3 becomes too strong, which causes aggravation of various aberrations and further changes the magnification from the wide-angle end state to the telephoto end state. At this time, it is difficult to secure the amount of movement of the second lens group G2 and the third lens group G3, and it is difficult to suppress aberration fluctuations due to scaling, particularly fluctuations in curvature of field, which is not preferable. In order to ensure the effect of the conditional expression (2), the lower limit of the conditional expression (2) is set to 0.45, and further set to 0.48, 0.50, 0.53, 0.55. Is more desirable.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (3) shown below.

0.40 <(-f1B) / f1 <1.00 (3)
However,
f1: Focal length of the first lens group G1 f1B: Focal length of the first B lens group G1B of the first lens group G1

The conditional expression (3) defines the focal length of the first B lens group G1B with respect to the focal length of the first lens group G1, and is the focusing group in the first lens group G1 having a strong refractive power (power). This is a condition for optimizing the refractive power of the 1B lens group G1B. In order to simply suppress the aberration fluctuation in focusing to the nearest distance, the first A lens group G1A having a positive refractive power and the first B lens group G1B having a negative refractive power form a substantially afocal system, and the first C lens. It is better to let the group G1C play the role of master, but as will be described later, in the variable magnification optical system in which the magnification conversion optical group Gx falls within the fourth lens group G4, the first lens group G1 itself becomes too long. , It is difficult to configure itself. Even if the refractive power (power) of the first lens group G1 is increased, good optical performance can be obtained even with the first lens group G1 having a short optical total length by devising the refractive power arrangement in the first lens group G1.

Further, the tilt fluctuation of the first B lens group G1B actually occurs due to the focusing mechanism and the clearance due to the focusing. This tilt fluctuation causes blurring of the image plane and becomes a big problem.

If the upper limit value of the conditional expression (3) is exceeded, the tilt sensitivity of the first B lens group G1B becomes high, which causes blurring of the product, which is not preferable. In order to ensure the effect of the conditional expression (3), the upper limit of the conditional expression (3) is set to 0.95, and further set to 0.90, 0.85, 0.80, 0.76. Is more desirable.

When the value falls below the lower limit of the conditional expression (3), the total thickness of the entire first lens group G1 (Σ1 described later) increases, and the amount of movement of the focusing group when focusing from infinity to a close distance increases. , It is not preferable because the axial chromatic aberration also increases. In order to ensure the effect of the conditional expression (3), the lower limit of the conditional expression (3) is set to 0.45, and further set to 0.50, 0.55, 0.60, 0.65. Is more desirable.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (4) shown below.

0.30 <Σ1 / L1 <1.30 (4)
However,
Σ1: Distance on the optical axis from the lens surface on the most object side of the first lens group G1 to the lens surface on the image side L1: From the lens surface on the most object side of the first lens group G1 to the first lens group G1 Distance on the optical axis to the focal point on the image side

In the conditional equation (4), the surface of the lens on the most object side of the first lens group G1 is relative to the distance from the surface apex of the lens on the most object side of the first lens group G1 to the focal position of the first lens group G1. It defines the distance (total thickness) from the apex to the surface apex of the lens closest to the image. In order to shorten the total thickness Σ1, it is desirable that the rear main plane of the first lens group G1 is closest to the surface of the first lens group G1 on the object side. Since the first lens group G1 has a triplet structure, if the refractive power (power) of the first B lens group G1B is increased, the positions of the rear main plane and the front main plane of the entire first lens group G1 can be exchanged. However, the aberration of the first B lens group G1B itself becomes large, which is not preferable.

When the upper limit of the conditional expression (4) is exceeded, the axial light beam passing through the first B lens group G1B becomes substantially afocal, the first lens group G1 becomes longer and larger, and the magnification conversion optical group becomes the fourth lens group G4. When Gx is inserted, it cannot be configured. In order to ensure the effect of the conditional expression (4), the upper limit of the conditional expression (4) is set to 1.20, and further 1.10, 1.00, 0.90, 0.80, 0. It is more desirable to set it to .70 and 0.60.

If it is less than the lower limit of the conditional expression (4), the refractive power of the first B lens group G1B becomes strong, deterioration of various aberrations and tilt sensitivity become high, which is not preferable. In order to ensure the effect of the conditional expression (4), the lower limit of the conditional expression (4) is set to 0.33, and further 0.37, 0.40, 0.43, 0.47, 0. It is more desirable to set it to .50 and 0.53.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (5) shown below.

0.70 <f1C / f1 <1.65 (5)
However,
f1: Focal length of the first lens group G1 f1C: Focal length of the first C lens group G1C of the first lens group G1

Conditional expression (5) defines the focal length of the first C lens group G1C with respect to the focal length of the first lens group G1 for shortening the length (reducing the size) of the first lens group G1. It is a condition. The first lens group G1 can be shortened and reduced by increasing the tele ratio between the first A lens group G1A having a positive refractive power and the first B lens group G1B having a negative refractive power. This can be achieved by substantially carrying the refractive power (power) of the first lens group G1 by the first A lens group G1A and the first B lens group G1B, and reducing the contribution of the first C lens group G1C having a positive refractive power.

Within the range of the conditional expression (5), various aberrations such as spherical aberration and curvature of field can be reduced, which is preferable. In order to ensure the effect of the conditional expression (5), the upper limit of the conditional expression (5) is set to 1.60, and further set to 1.55, 1.50, 1.45, 1.41. Is more desirable.

Further, in order to ensure the effect of the conditional expression (5), the lower limit of the conditional expression (5) is set to 0.72, and further 0.73, 0.74, 0.80, 0.85, 0. It is more desirable to set it to .90 and 1.00.

Further, the variable magnification optical system ZL according to the present embodiment is inserted and removed at a position between the aperture aperture S and the image plane I of the variable magnification optical system ZL in order to change the focal length of the variable magnification optical system ZL. It has a magnification conversion optical group Gx to be performed. Specifically, as shown in FIG. 3, the magnification conversion optical group Gx is configured to be inserted and removed between the front group G4F and the rear group G4R of the fourth lens group G4 of the variable magnification optical system ZL. There is. Therefore, in the variable magnification optical system ZL according to the present embodiment, the air spacing (distance on the optical axis) between the front group G4F and the rear group G4R of the fourth lens group G4 is the air spacing in the fourth lens group G4. The largest air spacing is desirable.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (6) shown below.

0.15 <Dc / Σ4 <0.50 (6)
However,
Dc: Distance on the optical axis between the front group G4F and the rear group G4R of the fourth lens group G4 Σ4: Distance on the optical axis from the lens surface on the most object side to the lens surface on the image side of the fourth lens group G4

The conditional expression (6) is a front group G4F and a rear group G4R with respect to the distance on the optical axis (total thickness of the fourth lens group) from the lens surface on the most object side to the lens surface on the image side of the fourth lens group G4. It defines the distance on the optical axis with.

Within the range of the conditional expression (6), various aberrations such as spherical aberration and curvature of field can be reduced, which is preferable. In order to ensure the effect of the conditional expression (6), it is more desirable to set the upper limit value of the conditional expression (6) to 0.45, further to 0.42, 0.40, 0.37. ..

Further, in order to ensure the effect of the conditional expression (6), it is more desirable to set the lower limit value of the conditional expression (6) to 0.20, further to 0.25, 0.30, 0.32. ..

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (7) shown below.

0.02 <Dc / f4 <0.50 (7)
However,
Dc: Distance on the optical axis between the front group G4F and the rear group G4R of the fourth lens group G4 f4: Focal length of the fourth lens group G4

The conditional expression (7) defines the focal length of the fourth lens group G4 with respect to the total thickness of the fourth lens group.

Within the range of the conditional expression (7), various aberrations such as spherical aberration and curvature of field can be reduced, which is preferable. In order to ensure the effect of the conditional expression (7), the upper limit of the conditional expression (7) is set to 0.45, and further set to 0.40, 0.35, 0.30, 0.25. Is more desirable.

Further, in order to ensure the effect of the conditional expression (7), the lower limit of the conditional expression (7) is set to 0.025, and further 0.030, 0.050, 0.070, 0.100, 0. It is more desirable to set it to .120.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (8) shown below.

-2.00 <fw / f123w <2.00 (8)
However,
fw: Focal length of the entire system in the wide-angle end state f123w: Combined focal length of the first lens group G1, the second lens group G2, and the third lens group G3 in the wide-angle end state

Conditional expression (8) defines the focal length of the entire system in the wide-angle end state with respect to the combined focal length of the first lens group G1 to the third lens group G3 in the wide-angle end state.

Within the range of the conditional expression (8), various aberrations such as spherical aberration and curvature of field can be reduced, which is preferable. In order to ensure the effect of the conditional expression (8), the upper limit of the conditional expression (8) is 1.70, and further 1.50, 1.30, 1.10, 0.90, 0. It is more desirable to set it to .70 and 0.55.

Further, in order to ensure the effect of the conditional expression (8), the lower limit of the conditional expression (8) is set to -1.50, and further -1.00, -0.70, -0.50,-. It is more desirable to set it to 0.30, 0.00, 0.10.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (9) shown below.

0.70 <β3w / β3t <1.20 (9)
However,
β3w: Lateral magnification of the third lens group G3 in the wide-angle end state β3t: Lateral magnification of the third lens group G3 in the telephoto end state

The conditional expression (9) defines the ratio between the lateral magnification of the third lens group G3 in the wide-angle end state and the lateral magnification in the telephoto end state. Since the magnification of the three lens group G3 does not change or changes little due to the magnification change, and the way the light rays pass does not change or changes little, it is possible to configure the third lens group G3 with a smaller number of lenses. The fact that there is no change in magnification in the third lens group G3 means that the compensator can be sufficiently configured with a correspondingly large amount of movement.

Within the range of the conditional expression (9), various aberrations such as spherical aberration and curvature of field can be reduced, which is preferable. In order to ensure the effect of the conditional expression (9), the upper limit of the conditional expression (9) is 1.17, and further 1.15, 1.13, 1.10, 1.07, 1 It is more desirable to set it to 0.05 and 1.03.

Further, in order to ensure the effect of the conditional expression (9), the lower limit of the conditional expression (9) is set to 0.73, and further 0.75, 0.78, 0.80, 0.85, 0. It is more desirable to set it to .90.

Further, it is desirable that the variable magnification optical system ZL according to the present embodiment satisfies the conditional expression (10) shown below.

-2.00 <β4w <2.00 (10)
However,
β4w: Magnification of the 4th lens group G4 in the wide-angle end state

The conditional expression (10) defines the degree of convergence of the light flux emitting the third lens group G3 by the magnification of the fourth lens group G4. If the first lens group G1 to the third lens group G3 are used as the zoom unit and the fourth lens group G4 is used as the master unit, the lateral magnification of the third lens group G3 is unchanged in the case of afocal zoom. If the magnification conversion optical group Gx can be inserted and removed from the 4th lens group G4, it is better to use the emission light flux of the 3rd lens group G3 as the convergent light and use the refractive power (power) of the 4th lens group G4 weaker. desirable.

Of the front group G4F of the fourth lens group G4, the fourth B lens group G4B is a vibration-proof group, and it is necessary to increase the magnification. When the group Gx is inserted, the lateral magnification of the optical system (rear group G4R) following the magnification conversion optical group Gx is preferably a reduced magnification. The back focus and the fluctuation of the image plane can be suppressed before and after the magnification conversion optical group Gx is inserted. However, considering the detection accuracy of the camera's phase-difference autofocus, the exit pupil of the optical system must be close to some extent, and the magnification of the last lens group near the image plane must be magnified to boost the peripheral light beam. However, it has to be a complicated structure.

When the upper limit of the conditional expression (10) is exceeded, the degree of convergence after ejecting the third lens group G3 becomes stronger, and the fourth lens group G4 has a negative refractive power (power), and the Petzval image plane becomes positive. It is not preferable because it tends to fall down. In order to ensure the effect of the conditional expression (10), the upper limit of the conditional expression (10) is 1.70, and further 1.50, 1.30, 1.10, 0.90, 0. It is more desirable to set it to .70 and 0.55.

When it falls below the lower limit of the conditional expression (10), the degree of divergence after ejecting the third lens group G3 becomes stronger, and the fourth lens group G4 must have a strong positive refractive power (power), and the fourth A lens. The refractive power of the group G4A must be strengthened, and it is difficult to maintain the optical performance with only one positive lens and one negative lens. In order to ensure the effect of the conditional expression (10), the lower limit of the conditional expression (10) is set to -1.50, and further -1.00, -0.70, -0.50,-. It is more desirable to set it to 0.30, 0.00, 0.10.

Further, in the variable magnification optical system ZL according to the present embodiment, the first A lens group G1A has a positive lens, and at least one of the positive lenses of the first A lens group G1A has the conditional expression (11) shown below. It is desirable to be satisfied.

ΔθgF1 ≧ 0.025 (11)
However,
ΔθgF1: Abnormal dispersibility of the medium of the positive lens of the first A lens group G1A

Here, the anomalous dispersibility “ΔθgF” is expressed by the following equation as a deviation from the normal dispersion “θgF = agF + bgF × νd” of the partial dispersion ratio “θgF≡ (ng−nF) / (nF−nC)”.
ΔθgF = θgF− (agF + bgF × νd)

It is expressed by the following equation by substituting the coefficients “agF = 0.648327” and “bgF = −0.0018024” obtained from the reference glass of normal dispersion.
ΔθgF = θgF- (0.648327-0.0018024 × νd)

Note that nC, nF, and ng are refractive indexes of C line (wavelength λ = 656.3 nm), F line (wavelength λ = 486.1 nm), and g line (wavelength λ = 435.8 nm), respectively, and νd is It is the Abbe number of the d line (wavelength λ = 587.6 nm).

As described above, the anomalous dispersibility "ΔθgF1" of the medium of the positive lens of the first A lens group G1A is expressed by the following equation.
ΔθgF1 = θgF1- (0.648327-0.0018024 × νd1)

Conditional expression (11) defines the anomalous dispersibility of the medium of the positive lens included in the first A lens group G1A of the first lens group G1.

Within the range of the conditional expression (11), axial chromatic aberration and chromatic aberration of magnification can be reduced, which is preferable. In order to ensure the effect of the conditional expression (11), the lower limit of the conditional expression (11) is set to 0.028, and further 0.030, 0.032, 0.034, 0.036, 0. More preferably, it is .038, 0.040, 0.045, 0.050, 0.055, 0.062.

Further, in the variable magnification optical system ZL according to the present embodiment, the first lens group G1 has a positive lens, and the positive lens on the most object side of the first lens group G1 has the conditional expression (12) shown below. It is desirable to be satisfied.

ΔθgF2 ≧ 0.045 (12)
However,
ΔθgF2: Abnormal dispersion of the medium of the positive lens on the most object side of the first lens group G1 Here, similarly to the above, the anomalous dispersion of the medium of the positive lens on the most object side of the first lens group G1 “ΔθgF2” It is expressed by the following formula.
ΔθgF2 = θgF2- (0.648327-0.0018024 × νd2)

The conditional expression (12) defines the anomalous dispersibility of the medium of the positive lens on the most object side of the first lens group G1.

Within the range of the conditional expression (12), axial chromatic aberration and chromatic aberration of magnification can be reduced, which is preferable. In order to ensure the effect of the conditional expression (12), the lower limit of the conditional expression (12) is set to 0.048, and further 0.050, 0.053, 0.055, 0.058, 0. It is more desirable to set it to .060 and 0.062.

Further, in the variable magnification optical system ZL according to the present embodiment, it is desirable that the positive lens on the most object side of the first lens group G1 satisfies the condition formula (13) shown below.

0.17 <f1C / fg1 (13)
However,
f1C: Focal length of the first C lens group G1C of the first lens group G1 fg1: Focal length of the positive lens on the most object side of the first lens group G1

Conditional expression (13) defines the focal length of the first C lens group G1C with respect to the focal length of the positive lens on the most object side of the first lens group G1.

Within the range of the conditional expression (13), various aberrations such as spherical aberration and curvature of field can be reduced, which is preferable. In order to ensure the effect of the conditional expression (13), the lower limit of the conditional expression (13) is set to 0.20, and further 0.23, 0.25, 0.28, 0.30, 0. It is more desirable to set it to .40 and 0.50.

It should be noted that the conditions and configurations described above each exert the above-mentioned effects, and are not limited to those satisfying all the conditions and configurations, and any of the conditions or configurations, or any of them. It is possible to obtain the above-mentioned effect even if the combination of the above conditions or configurations is satisfied.

Next, a camera, which is an optical device provided with the variable magnification optical system ZL according to the present embodiment, will be described with reference to FIG. This camera 1 is a so-called mirrorless camera of an interchangeable lens type provided with the variable magnification optical system ZL according to the present embodiment as a 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 photoelectrically converted by the image pickup unit 3 is stored in the memory (not shown). In this way, the photographer can shoot the subject with the camera 1. In this embodiment, an example of a mirrorless camera has been described, but a single-lens reflex type camera having a quick return mirror in the camera body and observing a subject by a finder optical system is used as a variable magnification optical system ZL according to the present embodiment. Even when the camera 1 is mounted, the same effect as that of the camera 1 can be obtained.

Further, the contents described below can be appropriately adopted as long as the optical performance is not impaired.

In the present embodiment, the variable magnification optical system ZL having a 4-group configuration is shown, but the above configuration conditions and the like can be applied to other group configurations such as 5 groups and 6 groups. Further, a configuration in which a lens or a lens group is added on the most object side or a configuration in which a lens or a lens group is added on the most image side may be used. Specifically, it is conceivable to add a lens group whose position with respect to the image plane is fixed at the time of magnification change or focusing on the most image side. Further, the lens group refers to a portion having at least one lens separated by an air interval that changes at the time of magnification change or focusing. Further, the lens component means a single lens or a bonded lens in which a plurality of lenses are bonded.

Further, a single lens group, a plurality of lens groups, or a partial lens group may be moved in the optical axis direction to focus on a short-distance object from an infinity object. In this case, the focusing group can also be applied to autofocus, and is also suitable for driving a motor (such as an ultrasonic motor) for autofocus. In particular, it is preferable that at least a part of the first lens group G1 (first B lens group G1B) is the focusing group, and the positions of the other lenses with respect to the image plane are fixed at the time of focusing. Considering the load applied to the motor, the focusing group is preferably composed of a single lens.

In addition, the lens group or partial lens group is moved so as to have a displacement component in the direction orthogonal to the optical axis, or is rotationally moved (swinged) in the in-plane direction including the optical axis to correct image blur caused by camera shake. It may be an anti-vibration group. In particular, it is preferable that at least a part of the fourth lens group G4 (fourth lens group G4B) is an anti-vibration group.

Further, the lens surface may be formed on a spherical surface or a flat surface, or may be formed on an aspherical surface. When the lens surface is spherical or flat, lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to processing and assembly adjustment errors 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, the aspherical surface is an aspherical surface formed by grinding, a glass mold aspherical surface formed by forming glass into an aspherical shape, or a composite aspherical surface formed by forming resin on the glass surface into an aspherical shape. Any aspherical surface may be used. 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.

The aperture diaphragm S is preferably arranged on the object side of the fourth lens group G4 (between the third lens group G3 and the fourth lens group G4), but the lens does not have a member as an aperture diaphragm. The frame may substitute for that role.

Further, each lens surface may be provided with an antireflection film having high transmittance in a wide wavelength range in order to reduce flare and ghost and achieve high optical performance with high contrast.

Further, the variable magnification optical system ZL of the present embodiment has a magnification ratio of about 1.5 to 5.0 times.

Hereinafter, an outline of a method for manufacturing the variable magnification optical system ZL according to the present embodiment will be described with reference to FIG.

First, each lens is arranged to prepare each lens group of the variable magnification optical system ZL (step S100). Further, at the time of scaling, the second lens group G2 and the third lens group G3 are arranged so as to move in the optical axis direction (step S200). Further, in the first lens group G1, in order from the object side, a first A lens group G1A having a positive refractive power, a first B lens group G1B having a negative refractive power, and a first C lens group having a positive refractive power. G1C and are arranged (step S300). Further, the fourth lens group G4 has a front group G4F, which is a vibration-proof group that moves in order from the object side so that at least a part of the lens group has a displacement component in a direction orthogonal to the optical axis, and a rear group G4F having a positive refractive power. The group G4R and the group G4R are arranged (step S400). Further, upon focusing, the first B lens group G1B is arranged so as to move in the optical axis direction (step S500). Then, the variable magnification optical system ZL is arranged so as to satisfy the condition according to the predetermined conditional expression (for example, the above-mentioned conditional expression (1)) (step S600).

Specifically, in the present embodiment, for example, as shown in FIG. 1, as the variable magnification optical system ZL, the biconvex positive lens L11, the biconvex positive lens L12, the biconcave negative lens L13, and the object side are sequentially arranged from the object side. A junction lens in which a negative meniscus lens L14 with a convex surface facing toward the object and a positive meniscus lens L15 with a convex surface facing the object side are joined, and a bonding lens in which a positive meniscus lens L16 with a concave surface facing the object side and both concave negative lenses L17 are joined. A plano-convex positive lens L18 whose lens surface on the object side is flat is arranged to form the first lens group G1, and a plano-concave negative lens L21 and biconvex negative lens L22 whose lens surface on the object side is flat are biconvex. A junction lens in which a positive lens L23 is joined and a plano-concave negative lens L24 whose lens surface on the image side is flat are arranged to form a second lens group G2, and a biconvex positive lens L31 and a biconvex positive lens L32. A bonding lens bonded to a negative meniscus lens L33 with a concave surface facing the object side is arranged to form a third lens group G3, and a bonding lens L41 having a convex surface facing the object side and a biconvex positive lens L42 bonded to each other. Lens, a junction lens in which a positive meniscus lens L43 with a concave surface facing the object side and a biconcave negative lens L44 are joined, a biconcave negative lens L45, a biconvex positive lens L46, and a negative meniscus lens L47 with a concave surface facing the object side. A junction lens, a positive meniscus lens L48 with a convex surface facing the object side, a junction lens L49 with a biconvex positive lens L49 and a negative meniscus lens L410 with a concave surface facing the object side, an optical filter FL1, a lens on the image side. A plano-convex positive lens L411 having a flat surface and a biconcave negative lens L412 are arranged to form a fourth lens group G4. The aperture diaphragm S is arranged on the object side of the fourth lens group G4.

Then, each lens group prepared in this way is arranged according to the procedure described above to manufacture the variable magnification optical system ZL.

With the above configuration, in the variable magnification optical system ZL having a long focal length to some extent, not only the size and lightness of the lens but also the thinness and weight that are easy to handle as a product including the members of the mechanical part are provided. It is possible to provide a variable-magnification optical system ZL having a more stable and high imaging performance, an optical device having this variable-magnification optical system ZL, and a method for manufacturing the variable-magnification optical system ZL.

Hereinafter, each embodiment of the present application will be described with reference to the drawings. It should be noted that FIG. 1, FIG. 3, and FIG. 5 are cross-sectional views showing the configuration and refractive power distribution of the variable magnification optical system ZL (ZL1 to ZL2) according to each embodiment. Further, in the lower part of the cross-sectional view of the variable magnification optical systems ZL1 to ZL2 in FIGS. 1 and 5, the light of each lens group G1 to G4 when the magnification is changed from the wide-angle end state (W) to the telephoto end state (T). The direction of movement along the axis is indicated by an arrow.

[First Example]
1 and 3 are diagrams showing the configuration of the variable magnification optical system ZL1 according to the first embodiment. In this variable magnification optical system ZL1, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. And a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes a first A lens group G1A having a positive refractive power, a first B lens group G1B having a negative refractive power, and a first C lens group G1C having a positive refractive power in order from the object side. , Consists of.

The first A lens group G1A includes a biconvex positive lens L11, a biconvex positive lens L12, a biconcave negative lens L13, a negative meniscus lens L14 with a convex surface facing the object side, and a convex surface facing the object side, in order from the object side. It is composed of a bonded lens in which a positive meniscus lens L15 is bonded.

The first B lens group G1B is composed of a bonded lens in which a positive meniscus lens L16 having a concave surface facing the object side and a biconcave negative lens L17 are joined in order from the object side.

The first C lens group G1C is composed of a plano-convex regular lens L18 whose lens surface on the object side is a flat surface.

The second lens group G2 includes a plano-concave positive lens L21 having a flat lens surface on the object side, a junction lens in which a biconcave negative lens L22 and a biconvex positive lens L23 are joined, and an image side in order from the object side. It is composed of a plano-concave negative lens L24 whose lens surface is flat.

The third lens group G3 is composed of a biconvex positive lens L31 and a junction lens in which a biconvex positive lens L32 and a negative meniscus lens L33 with a concave surface facing the object side are joined in this order from the object side.

The fourth lens group G4 includes a fourth A lens group G4A having a positive refractive power, a fourth B lens group G4B having a negative refractive power, and a fourth C lens group G4C having a positive refractive power in order from the object side. It is composed of a fourth D lens group G4D having a positive refractive power. Here, the 4A lens group G4A, the 4B lens group G4B, and the 4C lens group G4C constitute the front group G4F, and the 4D lens group G4D constitutes the rear group G4R.

The fourth A lens group G4A is composed of a bonded lens in which a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42 are joined in order from the object side.

The fourth B lens group G4B is composed of a bonded lens in which a positive meniscus lens L43 having a concave surface facing the object side and a biconcave negative lens L44 are joined in order from the object side, and a biconcave negative lens L45.

The fourth C lens group G4C is a junction lens in which a biconvex positive lens L46 and a negative meniscus lens L47 with a concave surface facing the object side are joined in order from the object side, and a positive meniscus lens L48 with a convex surface facing the object side. It is configured.

The fourth D lens group G4D is a junction lens in which a biconvex positive lens L49 and a negative meniscus lens L410 with a concave surface facing the object side are joined in order from the object side, and a plano-convex positive lens L411 having a flat lens surface on the image side. , And both concave and negative lenses L412.

In this variable magnification optical system ZL1, the aperture diaphragm S is arranged on the object side of the fourth lens group G4 (between the third lens group G3 and the fourth lens group G4). Further, in the 4th D lens group G4D (a junction lens in which a biconvex positive lens L49 and a negative meniscus lens L410 with a concave surface facing the object side are joined, and a plano-convex positive lens L411 having a flat lens surface on the image side). The optical filter FL1 is arranged between them, and the optical filter FL2 is arranged between the fourth lens group G4 and the image plane I.

Further, in this variable magnification optical system ZL1, the first lens group G1 and the fourth lens group G4 are immovable (fixed with respect to the image plane I) when the magnification is changed from the wide-angle end state to the telephoto end state. The two lens group G2 moves in the optical axis direction (image side), and the third lens group G3 moves in the optical axis direction (convex toward the image side) in order to correct the fluctuation of the image plane position due to the scaling. Move (drawing a trajectory).

Further, in this variable magnification optical system ZL1, for focusing from infinity to a short-range object, the first B lens group G1B having a negative refractive power in the first lens group G1 is set as the focusing group, and this first B lens group is used. This is done by moving G1B in the image direction.

Further, in the variable magnification optical system ZL1, the correction (vibration isolation) of the image position when camera shake occurs is to move the 4th B lens group G4B as the vibration isolation group so as to have a displacement component in the direction orthogonal to the optical axis. Corrects image blur on the image plane.

Further, in this variable magnification optical system ZL1, in order to change the focal length range of the entire system of the variable magnification optical system ZL1, between the front group G4F and the rear group G4R constituting the fourth lens group G4 (fourth C lens). It has a magnification conversion optical group Gx that can be inserted and removed (between the group G4C and the 4th D lens group G4D).

The magnification conversion optical group Gx is, in order from the object side, a positive meniscus lens Lx1 with a convex surface facing the object side, a junction lens in which a biconvex positive lens Lx2 and a biconcave negative lens Lx3 are joined, and a negative with a convex surface facing the object side. It is composed of a junction lens in which a meniscus lens Lx4 and a positive meniscus lens Lx5 with a convex surface facing the object side are bonded, a biconcave negative lens Lx6, a biconvex positive lens Lx7 and a biconcave negative lens Lx8. ..

Table 1 below lists the specifications of the variable magnification optical system ZL1 when the magnification conversion optical group Gx corresponding to FIG. 1 is not inserted. In the overall specifications of Table 1, f is the focal length of the entire system of the variable magnification optical system ZL1, FNO is the F number, ω is the half angle of view [°], Y is the maximum image height, TL is the total length, and BF. Represents the back focus value for each of the wide-angle end state, the intermediate focal length state, and the telephoto end state. Here, the total length TL indicates the distance (actual distance and air equivalent length) on the optical axis from the lens surface (first surface) on the most object side to the image surface I at the time of infinite focusing. Further, the back focus BF indicates the distance (air equivalent length) on the optical axis from the lens surface (49th surface) closest to the image plane to the image plane I at the time of focusing at infinity. Further, in the lens data, the first column m is the order (plane number) of the lens surfaces from the object side along the traveling direction of the light beam, and the second column r is the radius of curvature of each lens surface in the third column. d is the distance (plane spacing) on the optical axis from each optical surface to the next optical surface, and the fourth column nd and the fifth column νd are the refractive index and Abbe number with respect to the d line (λ = 587.6 nm). Is shown. Further, the radius of curvature 0.0000 indicates a plane, and the refractive index of air 1.00000 is omitted. The focal length of the lens group indicates the surface number and the focal length of the starting surface of each lens group.

Here, "mm" is generally used as the unit of the focal length f, the radius of curvature r, the surface spacing d, and other lengths listed in all the following specification values, but the optical system is proportionally expanded or proportional. It is not limited to this because the same optical performance can be obtained even if the reduction is performed. Further, the description of these symbols and the description of the specification table are the same in the following examples.

(Table 1) First Example (when the magnification conversion optical group is not inserted)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 183.600 300.000 392.000
FNO = 4.082 4.083 4.085
ω [°] = 6.787 4.091 3.112
Y = 21.6 21.6 21.6
TL (actual distance) = 389.811 389.811 381.811
TL (air equivalent length) = 389.129 389.129 381.129
BF (air conversion length) = 53.409 53.409 53.409

[Lens data]
m r d nd ν d
Physical surface ∞
1 187.63100 12.850 1.43384 95.24
2 -1369.38670 0.200
3 131.46280 17.000 1.49782 82.57
4-452.91620 2.000
5 -436.79520 4.500 1.74950 35.33
6 601.85700 29.883
7 97.11400 3.500 1.77250 49.62
8 56.03280 13.900 1.49782 82.57
9 497.12390 7.364
10 -329.20900 3.500 1.80610 33.27
11 -156.14630 3.000 1.48749 70.32
12 79.13050 28.015
13 0.00000 4.300 1.72916 54.61
14 -182.95440 D1
15 0.00000 2.000 1.88100 40.14
16 59.70290 4.237
17 -88.83170 2.000 1.49782 82.57
18 65.44280 5.000 1.78472 25.71
19 -338.95290 1.745
20 -71.44080 2.000 1.49782 82.57
21 0.00000 D2
22 195.48250 4.500 1.56883 56.00
23 -105.02730 0.100
24 230.27940 5.200 1.49782 82.57
25 -70.92610 2.000 1.92119 23.96
26 -158.85560 D3
27 0.00000 7.042 Aperture aperture S
28 94.31720 1.800 1.95375 32.33
29 41.48400 5.800 1.59319 67.90
30 -381.00910 4.000
31 -479.76020 4.000 1.80809 22.74
32 -70.04550 1.800 1.49782 82.57
33 988.84400 1.494
34 -112.82940 1.800 1.83400 37.18
35 146.09070 4.974
36 215.49090 4.200 1.69895 30.06
37 -61.99000 1.800 1.95375 32.33
38 -385.90720 0.100
39 66.87560 3.400 1.54814 45.78
40 221.36370 39.558
41 340.03060 6.900 1.80610 40.97
42 -42.86090 2.100 1.95375 32.33
43 -86.94720 5.542
44 0.00000 1.500 1.51680 63.88
45 0.00000 5.608
46 80.60440 4.100 1.49782 82.57
47 0.00000 12.800
48 -75.31480 1.900 2.00100 29.12
49 191.29370 51.990
50 0.00000 2.000 1.51680 63.88
51 0.00000 0.100
Image plane ∞

[Lens group focal length]
Lens group Start surface Focal length 1st lens group 1 219.251
1st A lens group 1 156.202
1st B lens group 10 -151.671
1st C lens group 13 250.911
2nd lens group 15 -46.786
3rd lens group 22 97.736
4th lens group 27 277.352
4th A lens group 27 329.439
4th B lens group 31 -92.317
4th C lens group 36 136.044
4th D lens group 41 287.279

In this variable magnification optical system ZL1, the axial air gap D1 between the first lens group G1 and the second lens group G2, the axial air gap D2 between the second lens group G2 and the third lens group G3, and the third lens group G3. The axial air gap D3 between the lens group G3 and the aperture diaphragm S changes upon scaling. Table 2 below shows the variable intervals in each focal length state of the wide-angle end state, the intermediate focal length state, and the telephoto end state in the infinity focusing state.

(Table 2)
Wide-angle end state Intermediate focal length state Telephoto end state D1 2.100 24.430 31.667
D2 42.924 19.168 2.000
D3 9.686 11.112 21.042

Table 3 below lists the specifications of the variable magnification optical system ZL1 when the magnification conversion optical group Gx corresponding to FIG. 3 is inserted. In Table 3, the lens data relating to the magnification conversion optical group Gx is shown from the lens surface immediately before the object side in which the magnification conversion optical group Gx of the variable magnification optical system ZL1 is inserted into the optical path. That is, the lens data of the object surface and the first to 39th surfaces are the same as the lens data when the magnification conversion optical group Gx is not inserted as shown in Table 1, and thus are omitted in Table 3. Further, the focal length of the lens group is also the same as the focal length shown in Table 1 on the object side of the magnification conversion optical group Gx, so the first lens group G1 to the third lens group G3 are omitted. The same applies to the following examples.

(Table 3) First Example (when the magnification conversion optical group is inserted)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 256.702 419.611 548.556
FNO = 5.715 5.719 5.723
ω [°] = 4.757 2.889 2.204
Y = 21.6 21.6 21.6
TL (actual distance) = 389.689 389.734 381.784
TL (air equivalent length) = 389.008 389.052 381.008
BF (air conversion length) = 53.436 53.480 53.436

[Lens data]
m r d nd ν d
40 221.36370 2.570
41 31.41290 5.800 1.51742 52.20
42 306.61800 1.178
43 77.98440 4.500 1.72047 34.71
44 -77.98440 1.500 2.00100 29.12
45 6385.35810 1.316
46 107.28170 1.500 2.00100 29.12
47 18.51190 5.300 1.67270 32.12
48 144.18680 2.902
49 -332.69370 1.200 1.83481 42.73
50 32.12040 2.000
51 34.02200 4.200 1.72047 34.71
52 -45.71480 1.200 1.61800 63.34
53 45.71480 4.392
54 340.03060 6.900 1.80610 40.97
55 -42.86090 2.100 1.95375 32.33
56 -86.94720 5.542
57 0.00000 1.500 1.51680 63.88
58 0.00000 5.608
59 80.60440 4.100 1.49782 82.57
60 0.00000 12.800
61 -75.31480 1.900 2.00100 29.12
62 191.29370 54.117
63 0.00000 2.000 1.51680 63.88
64 0.00000 0.100
Image plane ∞

[Lens group focal length]
Lens group Start surface Focal length 4th lens group 27 -814.181
4th A lens group 27 329.439
4th B lens group 31 -92.317
4th C lens group 36 136.044
Magnification conversion optics 41 -360.176
4th D lens group 55 287.271

When the magnification conversion optical group Gx is inserted into this variable magnification optical system ZL1, the axial air spacing D1 between the first lens group G1 and the second lens group G2 and the second lens group G2 that change at the time of magnification change The axial air gap D2 between the third lens group G3 and the axial air gap D3 between the third lens group G3 and the aperture aperture S are the same as those in Table 2.

Table 4 below shows the values corresponding to each conditional expression in the variable magnification optical system ZL1. In Table 4, fw is the focal distance of the entire system in the wide-angle end state of the variable magnification optical system ZL1, ft is the focal distance of the entire system in the telescopic end state of the variable magnification optical system ZL1, and f1 is the first lens group G1. F1B is the focal distance of the first lens group G1B, f1C is the focal distance of the first C lens group G1C, f4 is the focal distance of the fourth lens group G4, and Σ1 is the most of the first lens group G1. The distance (total thickness) on the optical axis from the lens surface on the object side to the lens surface on the image side is L1 from the lens surface on the object side of the first lens group G1 to the image side of the first lens group G1. Σ4 is the distance on the optical axis to the focal point, Σ4 is the distance (total thickness) on the optical axis from the lens surface on the most object side to the lens surface on the image side of the fourth lens group G4, and Dc is the fourth lens group. The distance between the front group G4F and the rear group G4R of G4 on the optical axis, f123w is the combined focal distance of the first lens group G1, the second lens group G2, and the third lens group G3 in the wide-angle end state, and β3w is the wide angle. The lateral magnification of the third lens group G3 in the end state, β3t is the lateral magnification of the third lens group G3 in the telescopic end state, β4w is the magnification of the fourth lens group G4 in the wide-angle end state, and ΔθgF1 is the first A lens group. The anomalous dispersibility of the positive lens of G1A, ΔθgF2 is the anomalous dispersibility of the positive lens on the most object side of the first lens group G1, and fg1 is the focal distance of the positive lens on the most object side of the first lens group G1. Represents. Since the first A lens group G1A has two positive lenses, the values of ΔθgF1 are displayed in order from the object side, separated by commas. The description of this reference numeral is the same in the following examples.

(Table 4)
f123w = 420.699
Σ1 = 130.012
L1 = 240.423
Σ4 = 115.176
Dc = 39.558
β3w = -2.383
β3t = -2.5500
β4w = 0.436
ΔθgF1 = 0.0649, 0.0391
ΔθgF2 = 0.0649
fg1 = 381.320

[Conditional expression correspondence value]
(1) f1 / ft = 0559
(2) f4 / ft = 0.708
(3) (-f1B) /f1=0.692
(4) Σ1 / L1 = 0.541
(5) f1C / f1 = 1.144
(6) Dc / Σ4 = 0.343
(7) Dc / f4 = 0.143
(8) fw / f123w = 0.436
(9) β3w / β3t = 0.953
(10) β4w = 0.436
(11) ΔθgF1 = 0.0649, 0.0391
(12) ΔθgF2 = 0.0649
(13) f1C / fg1 = 0.658

As described above, the variable magnification optical system ZL1 satisfies all of the above conditional expressions (1) to (13).

When the magnification conversion optical group Gx is not inserted in this variable magnification optical system ZL1, the spherical aberration diagram, non-point aberration diagram, and distortion aberration in the wide-angle end state, intermediate focal length state, and telephoto end state at the time of infinity focusing The figure, the chromatic aberration of magnification diagram, and the coma aberration diagram are shown in FIG. 2, and the wide-angle end state and the telephoto end at the time of infinity focusing when the magnification conversion optical group Gx is inserted in the variable magnification optical system ZL1. FIG. 4 shows various aberration diagrams of the spherical aberration diagram, the non-point aberration diagram, the distortion aberration diagram, the magnification chromatic aberration diagram, and the coma aberration diagram in the state. In each aberration diagram, FNO indicates an F number and Y indicates an image height. The spherical aberration diagram shows the value of the F number corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the transverse aberration diagram shows the value of each image height. D is the d line (λ = 587.6 nm), G is the g line (λ = 435.8 nm), F is the F line (λ = 486.1 nm), and C is the C line (λ = 656.3 nm). .. In the astigmatism diagram, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. Further, in the aberration diagram of each embodiment shown below, the same reference numerals as those of this embodiment are used. From each of these aberration diagrams, in this variable magnification optical system ZL1, various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state regardless of whether the magnification conversion optical group Gx is inserted or not. You can see that.

[Second Example]
FIG. 5 is a diagram showing a configuration of the variable magnification optical system ZL2 according to the second embodiment. In this variable magnification optical system ZL2, in order from the object side, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a third lens group G3 having a positive refractive power. And a fourth lens group G4 having a positive refractive power.

The first lens group G1 includes a first A lens group G1A having a positive refractive power, a first B lens group G1B having a negative refractive power, and a first C lens group G1C having a positive refractive power in order from the object side. , Consists of.

The first A lens group G1A includes a biconvex positive lens L11, a biconvex positive lens L12, a biconcave negative lens L13, a negative meniscus lens L14 with a convex surface facing the object side, and a convex surface facing the object side, in order from the object side. It is composed of a bonded lens in which a positive meniscus lens L15 is bonded.

The first B lens group G1B is composed of a bonded lens in which a positive meniscus lens L16 having a concave surface facing the object side and a biconcave negative lens L17 are joined in order from the object side.

The first C lens group G1C is composed of a positive meniscus lens L18 with a concave surface facing the object side.

The second lens group G2 is, in order from the object side, a biconcave negative lens L21, a junction lens in which a biconcave negative lens L22 and a biconvex positive lens L23 are joined, and a negative meniscus lens L24 with a concave surface facing the image side. It is configured.

The third lens group G3 is a bonded lens in which a positive meniscus lens L31 having a concave surface facing the object side and a biconvex positive lens L32 and a negative meniscus lens L33 having a concave surface facing the object side are joined in order from the object side. It is configured.

The fourth lens group G4 includes a fourth A lens group G4A having a positive refractive power, a fourth B lens group G4B having a negative refractive power, and a fourth C lens group G4C having a positive refractive power in order from the object side. It is composed of a fourth D lens group G4D having a positive refractive power. Here, the 4A lens group G4A, the 4B lens group G4B, and the 4C lens group G4C constitute the front group G4F, and the 4D lens group G4D constitutes the rear group G4R.

The fourth A lens group G4A is composed of a bonded lens in which a negative meniscus lens L41 having a convex surface facing the object side and a biconvex positive lens L42 are joined in order from the object side.

The fourth B lens group G4B is a bonded lens in which a positive meniscus lens L43 having a concave surface facing the object side and a negative meniscus lens L44 having a concave surface facing the object side are joined in order from the object side, and a biconcave negative lens L45. It is configured.

The 4th C lens group G4C is a bonded lens in which a negative meniscus lens L46 having a convex surface facing the object side and a positive meniscus lens L47 having a convex surface facing the object side are joined in order from the object side, and a convex surface facing the object side. It is composed of a positive meniscus lens L48.

The fourth D lens group G4D is a junction lens in which a negative meniscus lens L49 having a convex surface facing the object side and a biconvex positive lens L410 are joined, a biconvex positive lens L411, and a biconcave negative lens L412 in order from the object side. It is configured.

In this variable magnification optical system ZL2, the aperture diaphragm S is arranged on the object side of the fourth lens group G4 (between the third lens group G3 and the fourth lens group G4). Further, the optical filter FL1 is arranged in the 4th D lens group G4D (between the junction lens in which the negative meniscus lens L49 with the convex surface facing the object side and the biconvex positive lens L410 are joined and the biconvex positive lens L411). The optical filter FL2 is arranged between the fourth lens group G4 and the image plane I.

Further, in this variable magnification optical system ZL2, the first lens group G1 and the fourth lens group G4 are immovable (fixed with respect to the image plane I) when the magnification is changed from the wide-angle end state to the telephoto end state. The two lens group G2 moves in the optical axis direction (image side), and the third lens group G3 moves in the optical axis direction (convex toward the image side) in order to correct the fluctuation of the image plane position due to the scaling. Move (drawing a trajectory).

Further, in this variable magnification optical system ZL2, for focusing from infinity to a short-range object, the first B lens group G1B having a negative refractive power in the first lens group G1 is set as the focusing group, and this first B lens group is used. This is done by moving G1B in the image direction.

Further, in the variable magnification optical system ZL2, the correction (vibration isolation) of the image position when camera shake occurs is to move the 4th B lens group G4B as the vibration isolation group so as to have a displacement component in the direction orthogonal to the optical axis. Corrects the image shake on the image plane.

Further, in this variable magnification optical system ZL2, in order to change the focal length range of the entire system of the variable magnification optical system ZL2, between the front group G4F and the rear group G4R constituting the fourth lens group G4 (fourth C lens). (Between the group G4C and the 4th D lens group G4D), the magnification conversion optical group Gx shown in the first embodiment can be inserted and removed.

Table 5 below lists the specifications of the variable magnification optical system ZL2 when the magnification conversion optical group Gx corresponding to FIG. 5 is not inserted.

(Table 5) Second Example (when the magnification conversion optical group is not inserted)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telescopic end state f = 183.329 299.589 391.529
FNO = 4.081 4.083 4.084
ω [°] = 6.756 4.082 3.109
Y = 21.6 21.6 21.6
TL (actual distance) = 391.670 391.693 391.719
TL (air equivalent length) = 390.989 391.012 391.151
BF (air equivalent length) = 52.881 52.904 53.043

[Lens data]
m r d nd ν d
Physical surface ∞
1 195.86860 11.891 1.43385 95.23
2 -1464.91720 0.100
3 137.99630 15.377 1.49782 82.57
4-451.66690 2.000
5 -439.48160 4.500 1.72047 34.71
6 681.80320 35.526
7 96.87320 3.500 1.77250 49.62
8 55.47360 11.565 1.49782 82.57
9 743.76790 6.708
10 -390.58260 3.471 1.79504 28.69
11 -169.67530 3.000 1.51680 63.88
12 87.25780 27.346
13 -1210.24780 3.298 1.72916 54.61
14 -197.18840 D1
15 -1431.36750 2.000 1.88100 40.14
16 63.40260 3.694
17 -91.25210 2.000 1.49782 82.57
18 68.81440 5.000 1.79585 24.55
19 -434.83490 1.644
20 -74.64730 2.000 1.49782 82.57
21 -1247.34830 D2
22 -1274.22840 2.581 1.69680 55.52
23 -228.17970 0.100
24 129.69780 6.200 1.49782 82.57
25 -57.46210 2.000 1.90200 25.26
26 -92.89130 D3
27 0.00000 6.500 Aperture aperture S
28 106.07700 1.800 1.95375 32.32
29 47.79910 5.600 1.58313 59.42
30 -231.21880 4.282
31 -152.17430 4.500 1.81482 22.95
32 -46.84270 1.800 1.63693 31.15
33 -118.43900 0.473
34 -88.58490 1.800 1.72636 54.76
35 128.42700 5.038
36 105.91330 1.800 1.90366 31.31
37 45.84410 4.907 1.69564 56.60
38 713.94380 0.100
39 64.36530 3.006 1.82884 27.32
40 113.47470 41.336
41 157.46610 2.000 1.82358 39.89
42 76.92590 5.014 1.64512 36.77
43 -221.70880 6.500
44 0.00000 1.500 1.51680 63.88
45 0.00000 6.500
46 143.52740 6.319 1.49782 82.57
47 -82.12030 11.094
48 -55.38040 2.000 2.00100 29.13
49 1758.36200 51.449
50 0.00000 2.000 1.51680 63.88
51 0.00000 0.113
Image plane ∞

[Lens group focal length]
Lens group Start surface Focal length 1st lens group 1 230.999
1st A lens group 1 153.981
1st B lens group 10 -157.734
1st C lens group 13 322.628
2nd lens group 15 -48.286
Third lens group 22 111.573
4th lens group 28 212.689
4th A lens group 28 263.775
4th B lens group 31 -98.906
4th C lens group 36 114.604
4th D lens group 41 1045.320

In this variable magnification optical system ZL2, the axial air gap D1 between the first lens group G1 and the second lens group G2, the axial air gap D2 between the second lens group G2 and the third lens group G3, and the third lens group G3. The axial air gap D3 between the lens group G3 and the aperture diaphragm S changes upon scaling. Table 6 below shows the variable intervals in each focal length state of the wide-angle end state, the intermediate focal length state, and the telephoto end state in the infinity focusing state.

(Table 6)
Wide-angle end state Intermediate focal length state Telephoto end state D1 2.101 26.757 35.180
D2 43.436 19.982 2.502
D3 13.203 12.000 21.057

Table 7 below shows the values corresponding to each conditional expression in the variable magnification optical system ZL2. Since the first A lens group G1A has two positive lenses, the values of ΔθgF1 are displayed in order from the object side, separated by commas.

(Table 7)
f123w = 665.574
Σ1 = 128.282
L1 = 245.040
Σ4 = 117.369
Dc = 41.336
β3w = -3.776
β3t = -3.852
β4w = 0.275
ΔθgF1 = 0.0619, 0.0391
ΔθgF2 = 0.0619
fg1 = 399.090

[Conditional expression correspondence value]
(1) f1 / ft = 0.589
(2) f4 / ft = 0.543
(3) (-f1B) /f1=0.672
(4) Σ1 / L1 = 0.524
(5) f1C / f1 = 1.397
(6) Dc / Σ4 = 0.352
(7) Dc / f4 = 0.194
(8) fw / f123w = 0.276
(9) β3w / β3t = 0.980
(10) β4w = 0.275
(11) ΔθgF1 = 0.0619, 0.0391
(12) ΔθgF2 = 0.0619
(13) f1C / fg1 = 0.808

As described above, the variable magnification optical system ZL2 satisfies all of the above conditional expressions (1) to (13).

When the magnification conversion optical group Gx is not inserted in this variable magnification optical system ZL2, the spherical aberration diagram, the non-point aberration diagram, and the distortion aberration in the wide-angle end state, the intermediate focal length state, and the telephoto end state at the time of infinity focusing FIG. 6 shows various aberration diagrams of the figure, the chromatic aberration of magnification diagram, and the coma aberration diagram. From each of these aberration diagrams, it can be seen that in this variable magnification optical system ZL2, various aberrations are satisfactorily corrected from the wide-angle end state to the telephoto end state.

1 Camera (optical equipment) ZS (ZS1 to ZS2) Variable magnification optical system G1 1st lens group G1A 1A lens group G1B 1B lens group G1C 1C lens group G2 2nd lens group G3 3rd lens group G4 4th lens Group G4F Front group G4B G4R Rear group

Claims (20)

From the object side,
The first lens group with positive refractive power and
A second lens group with negative refractive power,
A third lens group with positive refractive power,
It has a fourth lens group having a positive refractive power, and
Upon scaling, the second lens group and the third lens group move in the optical axis direction,
The first lens group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in order from the object side. death,
The fourth lens group includes a front group, which is a vibration-proof group that moves so that at least a part thereof has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive power, in order from the object side. Have,
Upon focusing, the first B lens group moves in the optical axis direction,
A variable magnification optical system characterized by satisfying the following conditions.
0.30 <f1 / ft <0.75
0.708 ≤ f4 / ft <3.00
However,
f1: Focal length of the first lens group
f4: Focal length of the fourth lens group ft: Focal length of the entire system in the telephoto end state From the object side,
The first lens group with positive refractive power and
A second lens group with negative refractive power,
A third lens group with positive refractive power,
It has a fourth lens group having a positive refractive power, and
Upon scaling, the second lens group and the third lens group move in the optical axis direction,
The first lens group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in order from the object side. death,
The first B lens group consists of a bonded lens in which a positive lens and a negative lens are joined.
The fourth lens group includes a front group, which is a vibration-proof group that moves so that at least a part thereof has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive power, in order from the object side. Have,
Upon focusing, the first B lens group moves in the optical axis direction,
A variable magnification optical system characterized by satisfying the following conditions.
0.30 <f1 / ft <0.75
However,
f1: Focal length of the first lens group ft: Focal length of the entire system in the telephoto end state From the object side,
The first lens group with positive refractive power and
A second lens group with negative refractive power,
A third lens group with positive refractive power,
It has a fourth lens group having a positive refractive power, and
Upon scaling, the second lens group and the third lens group move in the optical axis direction,
The first lens group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in order from the object side. death,
The fourth lens group includes a front group, which is a vibration-proof group that moves so that at least a part thereof has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive power, in order from the object side. Have,
The air spacing between the front group and the rear group of the fourth lens group is the largest air spacing among the air spacings in the fourth lens group.
Upon focusing, the first B lens group moves in the optical axis direction,
A variable magnification optical system characterized by satisfying the following conditions.
0.30 <f1 / ft <0.75
However,
f1: Focal length of the first lens group ft: Focal length of the entire system in the telephoto end state From the object side,
The first lens group with positive refractive power and
A second lens group with negative refractive power,
A third lens group with positive refractive power,
It has a fourth lens group having a positive refractive power, and
Upon scaling, the second lens group and the third lens group move in the optical axis direction,
The first lens group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in order from the object side. death,
The fourth lens group includes a front group, which is a vibration-proof group that moves so that at least a part thereof has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive power, in order from the object side. Have,
Upon focusing, the first B lens group moves in the optical axis direction,
A variable magnification optical system characterized by satisfying the following conditions.
0.30 <f1 / ft <0.75
0.15 <Dc / Σ4 <0.50
However,
f1: Focal length of the first lens group ft: Focal length of the entire system in the telephoto end state
Dc: The distance between the front group and the rear group of the fourth lens group on the optical axis.
Σ4: Distance on the optical axis from the lens surface on the most object side to the lens surface on the image side of the fourth lens group. From the object side,
The first lens group with positive refractive power and
A second lens group with negative refractive power,
A third lens group with positive refractive power,
It has a fourth lens group having a positive refractive power, and
Upon scaling, the second lens group and the third lens group move in the optical axis direction,
The first lens group includes a first A lens group having a positive refractive power, a first B lens group having a negative refractive power, and a first C lens group having a positive refractive power in order from the object side. death,
The fourth lens group includes a front group, which is a vibration-proof group that moves so that at least a part thereof has a displacement component in a direction orthogonal to the optical axis, and a rear group, which has a positive refractive power, in order from the object side. Have,
Upon focusing, the first B lens group moves in the optical axis direction,
Satisfy the conditions of the following equation ,
0.30 <f1 / ft <0.75
However,
f1: Focal length of the first lens group ft: Focal length of the entire system in the telephoto end state
The first lens group has a positive lens, and the positive lens on the most object side of the first lens group satisfies the condition of the following equation .
ΔθgF2 ≧ 0.045
0.17 <f1C / fg1
However,
ΔθgF2: Abnormal dispersibility of the medium of the positive lens on the most object side of the first lens group
f1C: Focal length of the first C lens group of the first lens group
fg1: Focal length of the positive lens on the most object side of the first lens group
Here, ΔθgF2 = θgF2- (0.648327-0.0018024 × νd2).
However,
θgF2≡ (ng-nF) / (nF-nC): Partial dispersion ratio of the medium of the positive lens on the most object side of the first lens group.
ng: Refractive index of the medium of the positive lens on the most object side of the first lens group with respect to the g line.
nF: Refractive index of the medium of the positive lens on the most object side of the first lens group with respect to the F line.
nC: Refractive index of the medium of the positive lens on the most object side of the first lens group with respect to the C line.
νd: Abbe number with respect to the d-line of the medium of the positive lens on the most object side of the first lens group. The variable magnification optical system according to claim 2 , wherein the air spacing between the front group and the rear group of the fourth lens group is the largest air spacing among the air spacings in the fourth lens group. .. The variable magnification optical system according to any one of claims 2, 3 and 6, wherein the conditions of the following equation are satisfied.
0.15 <Dc / Σ4 <0.50
However,
Dc: Distance on the optical axis between the front group and the rear group of the fourth lens group Σ4: On the optical axis from the lens surface on the most object side to the lens surface on the image side of the fourth lens group The first lens group has a positive lens, and the positive lens on the most object side of the first lens group satisfies the condition of the following equation, claim 2, 3, 4, 6, 7. The variable magnification optical system according to any one of the above.
ΔθgF2 ≧ 0.045
0.17 <f1C / fg1
However,
ΔθgF2: Abnormal dispersibility of the medium of the positive lens on the most object side of the first lens group f1C: Focal length of the first C lens group of the first lens group fg1: Of the positive lens on the most object side of the first lens group Focal length Here, let ΔθgF2 = θgF2- (0.648327-0.0018024 × νd2).
However,
θgF2≡ (ng-nF) / (nF-nC): Partial dispersion ratio of the medium of the positive lens on the most object side of the first lens group ng: g of the medium of the positive lens on the most object side of the first lens group Refractive rate with respect to line nF: Refractive coefficient with respect to F line of the medium of the positive lens on the most object side of the first lens group nC: Refractive coefficient of the medium of the positive lens on the most object side of the first lens group with respect to C line νd: Abbe number with respect to d-line of the medium of the positive lens on the most object side of the first lens group The variable magnification optical system according to any one of claims 2 to 8, wherein the variable magnification optical system satisfies the condition of the following equation.
0.42 <f4 / ft <3.00
However,
f4: Focal length of the fourth lens group ft: Focal length of the entire system in the telephoto end state The variable magnification optical system according to any one of claims 1 to 9, wherein the first lens group is fixed to an image plane at the time of magnification change. The variable magnification optical system according to any one of claims 1 to 10, wherein the fourth lens group is fixed to an image plane at the time of magnification change. The variable magnification optical system according to any one of claims 1 to 11, wherein the variable magnification optical system satisfies the condition of the following equation.
0.40 <(-f1B) / f1 <1.00
However,
f1: Focal length of the first lens group f1B: Focal length of the first B lens group of the first lens group The variable magnification optical system according to any one of claims 1 to 12, wherein the variable magnification optical system satisfies the condition of the following equation.
0.30 <Σ1 / L1 <1.30
However,
Σ1: Distance on the optical axis from the lens surface on the most object side of the first lens group to the lens surface on the image side L1: Image of the first lens group from the lens surface on the most object side of the first lens group Distance on the optical axis to the side focal point The variable magnification optical system according to any one of claims 1 to 13, wherein the variable magnification optical system satisfies the condition of the following equation.
0.70 <f1C / f1 <1.65
However,
f1: Focal length of the first lens group f1C: Focal length of the first C lens group of the first lens group The variable magnification optical system according to any one of claims 1 to 14, wherein the variable magnification optical system satisfies the condition of the following equation.
0.02 <Dc / f4 <0.50
However,
Dc: Distance on the optical axis between the front group and the rear group of the fourth lens group f4: Focal length of the fourth lens group The variable magnification optical system according to any one of claims 1 to 15, wherein the variable magnification optical system satisfies the condition of the following equation.
-2.00 <fw / f123w <2.00
However,
fw: Focal length of the entire system in the wide-angle end state f123w: Combined focal length of the first lens group, the second lens group, and the third lens group in the wide-angle end state The variable magnification optical system according to any one of claims 1 to 16, wherein the variable magnification optical system satisfies the condition of the following equation.
0.70 <β3w / β3t <1.20
However,
β3w: Lateral magnification of the third lens group in the wide-angle end state β3t: Lateral magnification of the third lens group in the telephoto end state The variable magnification optical system according to any one of claims 1 to 17, wherein the conditions of the following equation are satisfied.
-2.00 <β4w <2.00
However,
β4w: Magnification of the fourth lens group in the wide-angle end state The variable magnification optical according to any one of claims 1 to 18, wherein the first A lens group has a positive lens, and at least one of the positive lenses satisfies the condition of the following equation. system.
ΔθgF1 ≧ 0.025
However,
ΔθgF1: Abnormal dispersibility of the medium of the positive lens of the first A lens group Here, ΔθgF1 = θgF1- (0.648327-0.0018024 × νd1).
However,
θgF1≡ (ng-nF) / (nF-nC): Partial dispersion ratio of the medium of the positive lens of the first A lens group ng: Refractive coefficient of the medium of the positive lens of the first A lens group with respect to the g line nF: The first Refractive coefficient of the positive lens of the 1A lens group with respect to the F line nC: Refractive coefficient of the positive lens of the first A lens group with respect to the C line νd: Abbe number of the positive lens of the first A lens group with respect to the d line of the medium An optical device having the variable magnification optical system according to any one of claims 1 to 19.

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