JP6354222B2 - Zoom lens, optical device - Google Patents

Description

  The present invention relates to a zoom lens, an optical device, and a zoom lens manufacturing method suitable for an imaging device such as a digital camera, a video camera, and a silver salt film camera.

  In recent years, an image sensor used in an imaging apparatus such as a digital camera has been increased in the number of pixels. An imaging lens used in an imaging apparatus provided with a high-pixel imaging device is required to have high optical performance.

  Under such a background, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a positive refraction. Proposed zoom lens composed of a powerful fourth lens group, with variable magnification by changing the distance between adjacent lens groups, and moving the third lens group along the optical axis for focusing. (For example, see Patent Document 1).

JP 2001-343584 A

  However, the conventional zoom lens as described above has a problem that it is not sufficiently miniaturized. In addition, there is a problem in that optical performance deteriorates if an attempt is made to perform vibration isolation by moving a predetermined lens in a direction perpendicular to the optical axis.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a zoom lens, an optical device, and a zoom lens manufacturing method that are small in size and have good optical performance during image stabilization.

In order to solve the above problems, the present invention
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power Depending on the group, it consists essentially of four lens groups ,
During zooming, the distance between adjacent lens groups changes,
The second lens group includes, in order from the object side, a first partial group having a positive refractive power, a second partial group having a negative refractive power, an aperture stop, and a third partial group.
During zooming, the first lens group, the second lens group, and the third lens group move along the optical axis, and the position of the fourth lens group is fixed,
At the time of focusing, at least a part of the third lens group moves along the optical axis,
The first partial group or the second partial group in the second lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis,
Provided is a zoom lens that satisfies the following conditional expression.
0.15 <| fw / fvr | < 0.40
However,
fw: focal length of the zoom lens in the wide-angle end state fvr: focal length of the movable group
The present invention also provides
In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power Depending on the group, it consists essentially of four lens groups,
During zooming, the distance between adjacent lens groups changes,
The second lens group includes, in order from the object side, a first partial group having a positive refractive power, a second partial group having a negative refractive power, an aperture stop, and a third partial group.
During zooming, the first lens group, the second lens group, and the third lens group move along the optical axis, and the position of the fourth lens group is fixed,
At the time of focusing, at least a part of the third lens group moves along the optical axis,
The first partial group or the second partial group in the second lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis,
Provided is a zoom lens that satisfies the following conditional expression.
0.15 <| fw / fvr | <0.50
0.20 <| f2 / fvr | <0.60
However,
fw: focal length of the zoom lens in the wide-angle end state
fvr: focal length of the movable group
f2: Focal length of the second lens group

The present invention also provides
An optical apparatus comprising the zoom lens is provided.

  According to the present invention, it is possible to provide a zoom lens, an optical device, and a zoom lens manufacturing method that are small in size and have good optical performance during image stabilization.

FIGS. 1A and 1B are sectional views of the zoom lens according to the first example of the present application in the wide-angle end state and the telephoto end state, respectively. FIGS. 2A and 2B are graphs showing various aberrations when the zoom lens according to Example 1 of the present application is focused on an object at infinity in the wide-angle end state and the telephoto end state, respectively. 3 (a) and 3 (b) show coma aberration when image stabilization is performed at the time of focusing on an object at infinity in the wide-angle end state and the telephoto end state of the zoom lens according to Example 1 of the present application, respectively. FIG. FIGS. 4A and 4B are graphs showing various aberrations when focusing on a short-distance object in the wide-angle end state and the telephoto end state of the zoom lens according to Example 1 of the present application, respectively. FIGS. 5A and 5B are sectional views of the zoom lens according to the second example of the present application in the wide-angle end state and the telephoto end state, respectively. FIGS. 6A and 6B are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively. FIGS. 7 (a) and 7 (b) show coma aberration when image stabilization is performed at the time of focusing on an object at infinity in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively. FIG. FIGS. 8A and 8B are graphs showing various aberrations when focusing on a short-distance object in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively. FIG. 9 is a diagram showing a configuration of a camera including the zoom lens of the present application. FIG. 10 is a diagram showing an outline of the zoom lens manufacturing method of the present application.

Hereinafter, the zoom lens, the optical device, and the zoom lens manufacturing method of the present application will be described.
The zoom lens of the present application includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a positive refraction. A second lens group having a positive refractive power, a second partial group having a negative refractive power, and an aperture stop, in order from the object side. And the third partial group, and at the time of zooming, the first lens group, the second lens group, and the third lens group move along the optical axis, and the position of the fourth lens group is fixed. At the time of focusing, at least a part of the third lens group moves along the optical axis, and the first partial group or the second partial group in the second lens group is orthogonal to the optical axis as a movable group. And the following conditional expression (1) is satisfied. .
(1) 0.15 <| fw / fvr | <0.50
However,
fw: focal length of the zoom lens in the wide-angle end state fvr: focal length of the movable group

  As described above, the zoom lens of the present application includes, in order from the object side, the first lens group having a negative refractive power, the second lens group having a positive refractive power, and the third lens group having a negative refractive power. A fourth lens group having a positive refractive power, and the second lens group has a first partial group having a positive refractive power and a second partial group having a negative refractive power in order from the object side. And an aperture stop and a third partial group. With this configuration, the zoom lens of the present application can achieve good optical performance while having a high zoom ratio and a long focal length.

  In addition, as described above, the zoom lens of the present application moves so that the first partial group or the second partial group in the second lens group includes a component in a direction orthogonal to the optical axis as a movable group. Accordingly, it is possible to correct image blur due to camera shake or the like, that is, to perform image stabilization.

  Conditional expression (1) defines the refractive power of the movable group. By satisfying conditional expression (1), the zoom lens of the present application can satisfactorily suppress deterioration in optical performance during vibration isolation while achieving downsizing.

  If the corresponding value of conditional expression (1) of the zoom lens of the present application is below the lower limit value, the amount of movement of the movable group at the time of vibration isolation becomes too large. For this reason, since the zoom lens of this application will enlarge, it is unpreferable. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (1) to 0.20.

  On the other hand, if the corresponding value of conditional expression (1) of the zoom lens of the present application exceeds the upper limit value, the refractive power of the movable group becomes too large. For this reason, the eccentric coma, the lateral chromatic aberration, and the curvature of field are deteriorated at the time of image stabilization, which is not preferable. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 0.40.

  With the above configuration, it is possible to realize a zoom lens that is small and has good optical performance during image stabilization.

  In the zoom lens according to the present application, it is desirable that the third partial group has a positive refractive power. With this configuration, since the third partial group bears the main refractive power of the positive second lens group, it is possible to realize good aberration correction.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 0.50 <fw / f2 <0.90
However,
fw: focal length of the zoom lens in the wide-angle end state f2: focal length of the second lens group

  Conditional expression (2) defines the refractive power of the second lens group. The zoom lens of the present application can achieve good aberration correction and miniaturization by satisfying conditional expression (2).

  If the corresponding value of the conditional expression (2) of the zoom lens of the present application is below the lower limit value, the refractive power of the second lens group becomes too small, and the amount of movement for performing the desired zooming becomes large, resulting in an increase in size. I will invite you. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 0.60.

  On the other hand, if the corresponding value of conditional expression (2) of the zoom lens of the present application exceeds the upper limit value, the refractive power of the second lens group becomes too large, which is advantageous for downsizing. This increases the sensitivity of the lead. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 0.80.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 0.20 <| f2 / fvr | <0.60
However,
f2: focal length of the second lens group fvr: focal length of the movable group

  Conditional expression (3) defines the ratio between the refractive power of the second lens group and the refractive power of the movable group. By satisfying conditional expression (3), the zoom lens of the present application can satisfactorily suppress deterioration in optical performance during vibration isolation while achieving downsizing.

  If the corresponding value of conditional expression (3) of the zoom lens of the present application is below the lower limit value, the amount of movement of the movable group at the time of vibration isolation becomes too large. For this reason, since the zoom lens of this application will enlarge, it is unpreferable. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 0.30.

  On the other hand, when the corresponding value of conditional expression (3) of the zoom lens of the present application exceeds the upper limit value, the refractive power of the movable group becomes too large. For this reason, the eccentric coma, the lateral chromatic aberration, and the curvature of field are deteriorated at the time of image stabilization, which is not preferable. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 0.50.

  In the zoom lens of the present application, it is preferable that each of the first lens group, the second lens group, the third lens group, and the fourth lens group includes at least one aspheric surface. With this configuration, spherical aberration and field curvature can be favorably corrected.

  The optical apparatus of the present application is characterized by having the zoom lens having the above-described configuration. As a result, it is possible to realize an optical device that is small and has good optical performance during vibration isolation.

The zoom lens manufacturing method of the present application includes, in order from the object side, a first lens group having negative refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power; A zoom lens manufacturing method including a fourth lens group having a positive refractive power, wherein the second lens group includes, in order from the object side, a first partial group having a positive refractive power and a negative refractive power. The fourth lens group is fixed at the time of zooming, and the first lens group, the second lens group, and the third lens group are fixed to each other. The third lens group is moved along the optical axis, and at the time of focusing, at least a part of the third lens group is moved along the optical axis, and the first partial group in the second lens group is moved. Alternatively, the second partial group is formed as a movable group in a direction perpendicular to the optical axis. So as to move to contain the movable group is characterized in that so as to satisfy the following conditional expression (1). Thereby, it is possible to manufacture a zoom lens that is small and has good optical performance during image stabilization.
(1) 0.15 <| fw / fvr | <0.50
However,
fw: focal length of the zoom lens in the wide-angle end state fvr: focal length of the movable group

Hereinafter, zoom lenses according to numerical examples of the present application will be described with reference to the accompanying drawings.
(First embodiment)
FIGS. 1A and 1B are sectional views of the zoom lens according to the first example of the present application in the wide-angle end state and the telephoto end state, respectively. Note that arrows in FIG. 1 and FIG. 5 to be described later indicate the movement trajectory of each lens unit at the time of zooming from the wide-angle end state to the telephoto end state.
The zoom lens according to the present example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a negative refractive power. G3 and a fourth lens group G4 having a positive refractive power.

  The first lens group G1, in order from the object side, includes a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a positive meniscus lens L13 having a convex surface directed toward the object side. Consists of. The negative meniscus lens L12 has an aspheric lens surface on the object side and the image side.

The second lens group G2 includes, in order from the object side, a first partial group G2a having a positive refractive power, a second partial group G2b having a negative refractive power, an aperture stop S, and a first partial group having a positive refractive power. 3 subgroups G2c.
The first partial group G2a is composed of a biconvex positive lens L21.
The second partial group G2b includes a negative meniscus lens L22 having a concave surface directed toward the object side. The negative meniscus lens L22 has an aspheric lens surface on the object side.
The third partial group G2c is composed of a cemented lens of a negative meniscus lens L23 having a convex surface directed toward the object side and a biconvex positive lens L24 in order from the object side.

The third lens group G3 includes a negative meniscus lens L31 having a convex surface directed toward the object side. The negative meniscus lens L31 has aspherical object-side and image-side lens surfaces.
The fourth lens group G4 includes a positive meniscus lens L41 having a concave surface directed toward the object side. The positive meniscus lens L41 has an aspheric lens surface on the image side.

  With the above configuration, in the zoom lens according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state, and the second lens The first lens group G1 moves along the optical axis so that the air gap between the group G2 and the third lens group G3 increases and the air gap between the third lens group G3 and the fourth lens group G4 increases. The second lens group G2 and the third lens group G3 move toward the object side along the optical axis. The position of the fourth lens group G4 is fixed at the time of zooming. Further, the first partial group G2a, the second partial group G2b, the aperture stop S, and the third partial group G2c of the second lens group G2 move together during zooming.

In the zoom lens according to the present embodiment, the third lens group G3 is moved to the image side along the optical axis, thereby focusing from an object at infinity to a near object.
In the zoom lens according to the present example, the second partial group G2b in the second lens group G2 is moved as a movable group so as to include a component in a direction orthogonal to the optical axis, thereby performing image stabilization.

Table 1 below lists values of specifications of the zoom lens according to the present example.
In Table 1, f indicates the focal length, and BF indicates the back focus (the distance on the optical axis between the lens surface closest to the image side and the image plane I).

  In [Surface data], the surface number is the order of the optical surfaces counted from the object side, r is the radius of curvature, d is the surface interval (the interval between the nth surface (n is an integer) and the n + 1th surface), and nd is The refractive index for d-line (wavelength 587.6 nm) and νd indicate the Abbe number for d-line (wavelength 587.6 nm), respectively. Further, the object plane indicates the object plane, the variable indicates the variable plane spacing, the stop S indicates the aperture stop S, and the image plane indicates the image plane I. The radius of curvature r = ∞ indicates a plane. For the aspherical surface, * is added to the surface number, and the value of the paraxial radius of curvature is indicated in the column of the radius of curvature r. The description of the refractive index of air nd = 1.000 is omitted.

[Aspherical data] shows an aspherical coefficient and a conic constant when the shape of the aspherical surface shown in [Surface data] is expressed by the following equation.
x = (h ² / r) / [1+ {1−κ (h / r) ² } ^1/2 ]
+ A4h ⁴ + A6h ⁶ + A8h ⁸ + A10h ¹⁰
Here, h is the height in the direction perpendicular to the optical axis, x is the distance (sag amount) from the tangent plane of the apex of the aspheric surface to the aspheric surface at the height h, and κ is the conic constant. , A4, A6, A8, A10 are aspherical coefficients, and r is the radius of curvature of the reference sphere (paraxial radius of curvature). “E−n” (n is an integer) indicates “× 10 ⁻ⁿ ”, for example “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”. The secondary aspherical coefficient A2 is 0 and is not shown.

In [various data], FNO is the F number, 2ω is the angle of view (unit is “°”), Y is the image height, TL is the total length of the zoom lens according to the present embodiment (light from the first surface to the image surface I). (Distance on the axis), dn indicates a variable distance between the nth surface and the (n + 1) th surface. W represents the wide-angle end state, M represents the intermediate focal length state, and T represents the telephoto end state.
[Lens Group Data] indicates the start surface and focal length of each lens group.

In [Anti-Vibration Data], Z is the amount of shift of the movable group, that is, the amount of movement in the direction perpendicular to the optical axis, and θ is the rotation blur angle (tilt angle, unit is “°”) of the zoom lens according to the present embodiment. , K represents a vibration isolation coefficient.
[Conditional Expression Corresponding Value] indicates the corresponding value of each conditional expression of the zoom lens according to the present embodiment.

Here, the focal length f, the radius of curvature r, and other length units listed in Table 1 are generally “mm”. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.
In addition, the code | symbol of Table 1 described above shall be similarly used also in the table | surface of each Example mentioned later.

(Table 1) First Example
[Surface data]
Surface number r d nd νd
Object ∞ ∞

1 78.892 0.80 1.7450 52.4
2 10.034 1.71
* 3 17.452 1.00 1.8512 40.0
* 4 9.307 0.98
5 12.455 2.27 2.0007 25.5
6 26.745 Variable

7 15.912 1.59 1.6380 61.0
8 -36.986 1.13
* 9 -14.015 0.80 1.4978 82.6
10 -36.732 1.15
11 (Aperture S) ∞ 0.90
12 13.073 0.80 1.6133 35.8
13 5.489 2.81 1.4978 82.6
14 -33.124 Variable

* 15 -32.118 0.80 1.5452 63.7
* 16 43.926 Variable

17 -77.198 2.73 1.6263 60.3
* 18 -16.492 BF

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
3 0.000E + 00 1.232E-04 -1.192E-06 9.574E-09 -1.191E-11
4 0.000E + 00 -9.802E-06 -1.437E-06 -1.507E-08 -7.874E-11
9 0.000E + 00 2.704E-05 3.771E-06 -1.175E-07 0.000E + 00
15 0.000E + 00 4.690E-04 3.430E-05 -9.148E-07 0.000E + 00
16 0.000E + 00 6.793E-04 3.487E-05 -8.133E-07 0.000E + 00
18 0.000E + 00 5.620E-05 -1.305E-06 4.685E-09 7.830E-12

[Various data]
W T
f 10.20 29.40
FNO 3.6 6.35
2ω 77.6 ° 31.2 °
Y 8.20 8.20
TL 58.03 58.47
BF 12.89 12.89

(When focusing on an object at infinity)
W M T
f 10.20 18.60 29.40
d6 18.13 6.61 1.45
d14 2.12 7.29 13.58
d16 5.41 8.01 11.16
BF 12.89 12.89 12.89

[Lens group data]
Group start surface f
1 1 -16.57
2 7 14.62
3 15 -33.90
4 17 32.92

[Anti-vibration data]
W M T
f 10.20 18.60 29.40
Z 0.18 0.25 0.30
θ 0.5 0.5 0.5
K -0.50 -0.65 -0.84

[Conditional expression values]
fvr = -46.06
(1) | fw / fvr | = 0.22
(2) fw / f2 = 0.70
(3) | f2 / fvr | = 0.32

  FIGS. 2A and 2B are graphs showing various aberrations when the zoom lens according to Example 1 of the present application is focused on an object at infinity in the wide-angle end state and the telephoto end state, respectively. 3 (a) and 3 (b), respectively, perform vibration isolation against rotation blur of 0.5 ° when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 1 of the present application. FIG. 5 is a coma aberration diagram when the object is in the telephoto end state, and a coma aberration diagram when the image stabilization is performed with respect to a rotational blur of 0.5 ° at the time of focusing on an object at infinity. FIGS. 4A and 4B are graphs showing various aberrations when focusing on a short-distance object in the wide-angle end state and the telephoto end state of the zoom lens according to Example 1 of the present application, respectively.

  In each aberration diagram, FNO represents an F number, and Y represents an image height. d indicates the aberration at the d-line (wavelength 587.6 nm), g indicates the aberration at the g-line (wavelength 435.8 nm), and those without d and g indicate the aberration at the d-line. In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. The coma aberration diagram shows coma aberration at each image height Y. Note that the same reference numerals as in this embodiment are used in the aberration diagrams of each embodiment described later.

  From each aberration diagram, the zoom lens according to the present example has high optical performance with various aberrations corrected well from the wide-angle end state to the telephoto end state, and also has high optical performance even during image stabilization. I understand that.

(Second embodiment)
FIGS. 5A and 5B are sectional views of the zoom lens according to the second example of the present application in the wide-angle end state and the telephoto end state, respectively.
The zoom lens according to the present example includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, and a third lens group having a negative refractive power. G3 and a fourth lens group G4 having a positive refractive power.

  The first lens group G1, in order from the object side, includes a negative meniscus lens L11 having a convex surface directed toward the object side, a negative meniscus lens L12 having a convex surface directed toward the object side, and a positive meniscus lens L13 having a convex surface directed toward the object side. Consists of. The negative meniscus lens L12 has an aspheric lens surface on the image side.

The second lens group G2 includes, in order from the object side, a first partial group G2a having a positive refractive power, a second partial group G2b having a negative refractive power, an aperture stop S, and a first partial group having a positive refractive power. 3 subgroups G2c.
The first partial group G2a is composed of a biconvex positive lens L21. The positive lens L21 has an aspheric lens surface on the object side.
The second partial group G2b includes, in order from the object side, a cemented lens of a negative meniscus lens L22 having a convex surface facing the object side and a positive meniscus lens L23 having a convex surface facing the object side.
The third partial group G2c is composed of a biconvex positive lens L24.

The third lens group G3 includes a negative meniscus lens L31 having a convex surface directed toward the object side. The negative meniscus lens L31 has an aspheric lens surface on the image side.
The fourth lens group G4 includes a planoconvex positive lens L41 having a convex surface directed toward the object side. The positive lens L41 has an aspheric lens surface on the image side.

  With the above configuration, in the zoom lens according to the present embodiment, the air gap between the first lens group G1 and the second lens group G2 decreases during zooming from the wide-angle end state to the telephoto end state, and the second lens The first lens group G1 moves along the optical axis so that the air gap between the group G2 and the third lens group G3 increases and the air gap between the third lens group G3 and the fourth lens group G4 increases. The second lens group G2 and the third lens group G3 move toward the object side along the optical axis. The position of the fourth lens group G4 is fixed at the time of zooming. Further, the first partial group G2a, the second partial group G2b, the aperture stop S, and the third partial group G2c of the second lens group G2 move together during zooming.

In the zoom lens according to the present embodiment, the third lens group G3 is moved to the image side along the optical axis, thereby focusing from an object at infinity to a near object.
Further, in the zoom lens according to the present embodiment, the first partial group G2a in the second lens group G2 is moved as a movable group so as to include a component in a direction orthogonal to the optical axis, thereby performing image stabilization.
Table 2 below lists values of specifications of the zoom lens according to the present example.

(Table 2) Second Example
[Surface data]
Surface number r d nd νd
Object ∞ ∞

1 65.074 1.00 1.7678 49.7
2 10.582 2.22
3 21.472 1.00 1.7766 48.7
* 4 9.015 0.60
5 11.386 2.67 2.0006 25.5
6 22.956 Variable

* 7 15.422 1.20 1.4978 82.6
8 -460.710 1.48
9 9.744 0.60 1.8081 22.7
10 6.869 1.20 1.8830 40.8
11 7.816 2.11
12 (Aperture S) ∞ 1.50
13 14.686 1.63 1.4978 82.6
14 -19.110 Variable

15 10.782 0.80 1.6908 36.5
* 16 7.017 Variable

17 ∞ 2.50 1.7007 56.3
* 18 -28.026 BF

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8 A10
4 0.000E + 00 -1.642E-04 -1.853E-07 -1.249E-08 -2.299E-10
7 0.000E + 00 -1.148E-04 9.544E-07 -2.877E-08 -5.249E-10
16 0.000E + 00 -2.139E-05 1.247E-06 -5.518E-08 0.000E + 00
18 0.000E + 00 4.282E-05 -1.969E-06 1.391E-08 -3.253E-11

[Various data]
W T
f 10.2 29.40
FNO 3.6 6.35
2ω 77.6 ° 31.2 °
Y 8.20 8.20
TL 59.06 59.06
BF 12.58 12.58

(When focusing on an object at infinity)
W M T
f 10.20 19.99 29.40
d6 17.84 5.24 1.15
d14 1.61 7.63 12.53
d16 6.50 9.11 12.31
BF 12.58 12.58 12.58

[Lens group data]
Group start surface f
1 1 -15.4661
2 7 14.4691
3 15 -31.8519
4 17 40.0000

[Anti-vibration data]
W M T
f 10.20 19.99 29.40
Z 0.07 0.10 0.12
θ 0.3 0.3 0.3
K 0.80 1.04 1.27

[Conditional expression values]
fvr = 30.00
(1) | fw / fvr | = 0.34
(2) fw / f2 = 0.70
(3) | f2 / fvr | = 0.48

  FIGS. 6A and 6B are graphs showing various aberrations during focusing on an object at infinity in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively. FIG. 7A and FIG. 7B respectively perform vibration isolation against rotation blur of 0.3 ° when focusing on an object at infinity in the wide-angle end state of the zoom lens according to Example 2 of the present application. FIG. 6 is a coma aberration diagram when the camera is shaken, and a coma aberration diagram when the image stabilization is performed with respect to a rotational shake of 0.3 ° at the time of focusing on an object at infinity in the telephoto end state. FIGS. 8A and 8B are graphs showing various aberrations when focusing on a short-distance object in the wide-angle end state and the telephoto end state of the zoom lens according to Example 2 of the present application, respectively.

  From each aberration diagram, the zoom lens according to the present example has high optical performance with various aberrations corrected well from the wide-angle end state to the telephoto end state, and also has high optical performance even during image stabilization. I understand that.

  According to each of the above embodiments, it is possible to realize a zoom lens that has a short overall lens length, is small and light, has good optical performance, and has little deterioration in optical performance during vibration isolation. In addition, each said Example has shown one specific example of this invention, and this invention is not limited to these. The following contents can be appropriately adopted within a range that does not impair the optical performance of the zoom lens of the present application.

  Although a numerical example of the zoom lens of the present application has been described with a four-group configuration, the present application is not limited to this, and a zoom lens of another group configuration (for example, five groups) can also be configured. Specifically, a configuration in which a lens or a lens group is added to the most object side or the most image side of the zoom lens of the present application may be used.

  In addition, the zoom lens of the present application is used in order to focus from an object at infinity to an object at a short distance in the direction of the optical axis using a part of the lens group, the entire lens group, or a plurality of lens groups as the focusing lens group. It is good also as a structure moved to. In particular, it is preferable that at least a part of the third lens group is a focusing lens group. Such a focusing lens group can be applied to autofocus, and is also suitable for driving by an autofocus motor such as an ultrasonic motor.

  In the zoom lens of the present application, either the entire lens group or a part of the lens group is moved so as to include a component in a direction perpendicular to the optical axis as an anti-vibration lens group, or an in-plane direction including the optical axis It can also be set as the structure which carries out anti-vibration by carrying out rotational movement (oscillation) to (F). In particular, in the zoom lens of the present application, it is preferable that at least a part of the second lens group is an anti-vibration lens group.

  The lens surface of the lens constituting the zoom lens of the present application may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are easy, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspherical, any of aspherical surface by grinding, glass mold aspherical surface in which glass is molded into an aspherical shape, or composite aspherical surface in which resin provided on the glass surface is formed in an aspherical shape Good. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In the zoom lens of the present application, it is preferable that the aperture stop be disposed in the second lens group, and the role may be substituted by a lens frame without providing a member as the aperture stop.
Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the zoom lens of the present application. Thereby, flare and ghost can be reduced, and high optical performance with high contrast can be achieved.

Next, a camera equipped with the zoom lens of the present application will be described with reference to FIG.
FIG. 9 is a diagram illustrating a configuration of a camera including the zoom lens of the present application.
As shown in FIG. 9, the camera 1 is a so-called mirrorless camera of an interchangeable lens provided with the zoom lens according to the first embodiment as the photographing lens 2. Note that the zoom lens according to the first embodiment, which is the photographing lens 2, preferably has a structure in which the distance between the first lens group and the second lens group is reduced to reduce the size of the zoom lens when the lens is housed.

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

  Here, the zoom lens according to the first embodiment mounted on the camera 1 as the taking lens 2 is a zoom lens that is small in size and has good optical performance during image stabilization. Therefore, the present camera 1 can achieve good optical performance during vibration isolation while achieving downsizing. Note that even if a camera in which the zoom lens according to the second embodiment is mounted as the photographing lens 2, the same effect as the camera 1 can be obtained. Further, even when the zoom lens according to each of the above embodiments is mounted on a single-lens reflex camera having a quick return mirror and observing a subject with a finder optical system, the same effect as the camera 1 can be obtained.

Finally, the outline of the manufacturing method of the zoom lens of this application is demonstrated based on FIG.
The zoom lens manufacturing method of the present application shown in FIG. 10 includes, in order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens having a negative refractive power. A zoom lens manufacturing method including a lens group and a fourth lens group having a positive refractive power, and includes the following steps S1 to S5.

Step S1: The second lens group includes, in order from the object side, a first partial group having a positive refractive power, a second partial group having a negative refractive power, an aperture stop, and a third partial group. The first to fourth lens groups are arranged in order from the object side in the lens barrel.
Step S2: By providing a known moving mechanism in the lens barrel, the position of the fourth lens group is fixed and the first to third lens groups move along the optical axis during zooming. .

Step S3: A known moving mechanism is provided on the lens barrel so that at least a part of the third lens group moves along the optical axis during focusing.
Step S4: By providing a known moving mechanism on the lens barrel, the first partial group or the second partial group in the second lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis. Like that.

Step S5: The movable group is made to satisfy the following conditional expression (1).
(1) 0.15 <| fw / fvr | <0.50
However,
fw: focal length of zoom lens in wide-angle end state fvr: focal length of movable group

  According to the zoom lens manufacturing method of the present application, it is possible to manufacture a zoom lens that is small in size and has good optical performance during image stabilization.

G1 First lens group G2 Second lens group G2a First partial group G2b Second partial group G2c Third partial group G3 Third lens group G4 Fourth lens group S Aperture stop I Image surface

Claims (7)

In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power Depending on the group, it consists essentially of four lens groups ,
During zooming, the distance between adjacent lens groups changes,
The second lens group includes, in order from the object side, a first partial group having a positive refractive power, a second partial group having a negative refractive power, an aperture stop, and a third partial group.
During zooming, the first lens group, the second lens group, and the third lens group move along the optical axis, and the position of the fourth lens group is fixed,
At the time of focusing, at least a part of the third lens group moves along the optical axis,
The first partial group or the second partial group in the second lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis,
A zoom lens satisfying the following conditional expression:
0.15 <| fw / fvr | < 0.40
However,
fw: focal length of the zoom lens in the wide-angle end state fvr: focal length of the movable group In order from the object side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group having a negative refractive power, and a fourth lens having a positive refractive power Depending on the group, it consists essentially of four lens groups ,
During zooming, the distance between adjacent lens groups changes,
The second lens group includes, in order from the object side, a first partial group having a positive refractive power, a second partial group having a negative refractive power, an aperture stop, and a third partial group.
During zooming, the first lens group, the second lens group, and the third lens group move along the optical axis, and the position of the fourth lens group is fixed,
At the time of focusing, at least a part of the third lens group moves along the optical axis,
The first partial group or the second partial group in the second lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis,
A zoom lens satisfying the following conditional expression:
0.15 <| fw / fvr | <0.50
0.20 <| f2 / fvr | <0.60
However,
fw: focal length of the zoom lens in the wide-angle end state fvr: focal length of the movable group
f2: Focal length of the second lens group The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
0.20 <| f2 / fvr | <0.60
However,
f2: focal length of the second lens group fvr: focal length of the movable group The zoom lens according to any one of claims 1 to 3, wherein the third partial group has a positive refractive power. The zoom lens according to any one of claims 1 to 4, characterized by satisfying the following conditional expression.
0.50 <fw / f2 <0.90
However,
fw: focal length of the zoom lens in the wide-angle end state f2: focal length of the second lens group The first lens group, the second lens group, the third lens group and the fourth lens group, claim 5, further comprising at least one aspherical claim 1, wherein The zoom lens according to one item. An optical apparatus comprising the zoom lens according to any one of claims 1 to 6 .

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