JP2015172695A - Zoom lens, optical device, and method for manufacturing zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which achieves high optical performance during vibration isolation and during focusing on an object at a short distance.SOLUTION: The zoom lens includes, in order from the object side, a negative first lens group G1, a positive second lens group G2, a negative third lens group G3, and a positive fourth lens group G4. When varying power, the first to third lens groups G1 to G3 move along the optical axis, and the position of the fourth lens group G4 is fixed. When focusing, at least a part of the second lens group G2 moves as a focus group along the optical axis. At least a part of the third lens group G3 moves as a movable group so as to include a component in a direction perpendicular to the optical axis. The zoom lens satisfies a predetermined conditional expression.

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. A fourth lens group having power, and changing the distance between adjacent lens groups to perform zooming, moving the entire third lens group along the optical axis to perform focusing, and the second lens group A zoom lens has been proposed in which a part of the zoom lens is moved in a direction orthogonal to the optical axis to perform image stabilization (see, for example, Patent Document 1).

International Publication No. 2012/086153

  However, the conventional zoom lens as described above has a problem that the optical performance at the time of image stabilization and focusing on a short-distance object is not sufficient.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a zoom lens, an optical device, and a method for manufacturing the zoom lens, which have good optical performance during image stabilization and when focusing on a short distance object. To do.

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 A 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,
During focusing, at least a part of the second lens group moves along the optical axis as a focusing group,
Moving so that at least a part of the third lens group includes a component in a direction orthogonal to the optical axis as a movable group;
Provided is a zoom lens that satisfies the following conditional expression.
1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state

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

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 A zoom lens manufacturing method comprising:
During zooming, the position of the fourth lens group is fixed, and the first lens group, the second lens group, and the third lens group move along the optical axis,
At the time of focusing, at least a part of the second lens group moves along the optical axis as a focusing group,
At least a part of the third lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis;
A zoom lens manufacturing method is provided in which the focusing group satisfies the following conditional expression.
1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state

  According to the present invention, it is possible to provide a zoom lens, an optical device, and a method for manufacturing a zoom lens, which have good optical performance at the time of image stabilization and focusing on a short distance object.

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 fourth lens group having a force, 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 At the time of focusing, at least a part of the second lens group moves along the optical axis as a focusing group, and at least a part of the third lens group acts as a movable group in a direction perpendicular to the optical axis. It moves so that a component may be included, and the following conditional expression (1) is satisfied.
(1) 1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state

  As described above, the zoom lens of the present application moves so that at least a part of the third 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.

  As described above, the zoom lens according to 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 having a negative refractive power. And a fourth lens group having a positive refractive power. By appropriately setting the refractive power arrangement of each lens group in this way, the zoom lens of the present application has high zoom ratio and long focal length, while improving optical performance during vibration isolation and shortening the total lens length And good optical performance can be achieved. In particular, in the zoom lens of the present application, the second lens group includes, in order from the object side, a front lens group having a positive refractive power, an aperture stop, and a rear lens group having a positive refractive power. When the front lens group or the rear lens group of the second lens group is a focusing group, an air interval for focusing, that is, the focusing group moves during focusing, between the focusing group and the aperture stop. Space can be secured. In this case, the distance between the focusing group and the aperture stop may be changed during zooming.

  Conditional expression (1) defines the focal length of the focused group. By satisfying conditional expression (1), the zoom lens of the present application can satisfactorily correct various aberrations such as spherical aberration and coma during focusing while reducing the size.

  If the corresponding value of the conditional expression (1) of the zoom lens of the present application is less than the lower limit value, the refractive power of the focusing group increases, and spherical aberration and coma aberration are deteriorated during focusing. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (1) to 1.80.

  On the other hand, if the corresponding value of the conditional expression (1) of the zoom lens of the present application exceeds the upper limit value, the air interval for focusing becomes too large, leading to an increase in the total lens length. This makes it difficult to reduce the overall lens length and lens outer diameter when the cylinder is contracted. In addition, the refractive power of the lenses other than the focusing group in the second lens group is increased, leading to deterioration of decentering coma due to manufacturing errors. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (1) to 3.20.

  With the above configuration, it is possible to realize a zoom lens with good optical performance during image stabilization and when focusing on a short-distance object.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (2).
(2) 1.00 <| f3vr / fw | <5.00
However,
f3vr: focal length of the movable group fw: focal length of the zoom lens in the wide-angle end state

  Conditional expression (2) defines the focal length of the movable group. By satisfying conditional expression (2), the zoom lens according to the present application can satisfactorily correct various aberrations during image stabilization while achieving downsizing.

  When the corresponding value of the conditional expression (2) of the zoom lens of the present application is below the lower limit value, the sensitivity of the movable group increases, that is, when the movable group is decentered due to a manufacturing error or the like, the eccentric coma aberration, etc. The various aberrations are likely to occur. This makes it difficult to ensure good optical performance during vibration isolation. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 1.50. In order to further secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (2) to 1.80.

  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 moving amount of the movable group during vibration isolation increases, leading to an increase in the total lens length. Therefore, it becomes difficult to reduce the outer diameter of the zoom lens of the present application and the overall length of the lens when the lens barrel is contracted. Further, the refractive power of lenses other than the movable group in the third lens group or other lens groups is increased, and decentration coma aberration and decentration field curvature due to manufacturing errors are deteriorated. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 3.00. In order to further secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (2) to 2.50.

It is desirable that the zoom lens of the present application satisfies the following conditional expression (3).
(3) 1.00 <m12 / fw <2.50
However,
m12: Distance on the optical axis from the most image-side lens surface in the first lens group to the most object-side lens surface in the second lens group upon zooming from the wide-angle end state to the telephoto end state Change amount fw: focal length of the zoom lens in the wide angle end

  Conditional expression (3) defines the amount of change in the air gap between the first lens group and the second lens group upon zooming from the wide-angle end state to the telephoto end state. By satisfying conditional expression (3), the zoom lens of the present application can correct the curvature of field favorably while reducing the size.

  When the corresponding value of the conditional expression (3) of the zoom lens of the present application is less than the lower limit value, the burden at the time of zooming of the lens group other than the first lens group and the second lens group becomes large, and the refractive power of each lens group becomes Increase or the amount of movement of each lens group during zooming increases. For this reason, the decentration sensitivity increases, the optical performance deteriorates, and the total lens length increases. In particular, an increase in the refractive power of the third lens group causes the field curvature to deteriorate. In order to secure the effect of the present application, it is more preferable to set the lower limit of conditional expression (3) to 1.50.

  On the other hand, if the corresponding value of conditional expression (3) of the zoom lens of the present application exceeds the upper limit value, the total lens length increases. For this reason, it becomes difficult to reduce the outer diameter of the zoom lens of the present application and the overall length of the lens when the lens barrel is contracted. In addition, the increase in the total lens length leads to an increase in the total length of the lens barrel components such as the cam barrel, and the decentering state of each lens group is likely to fluctuate due to zooming. Is likely to occur. In order to secure the effect of the present application, it is more preferable to set the upper limit of conditional expression (3) to 2.00.

  The optical apparatus of the present application is characterized by having the zoom lens having the above-described configuration. Thereby, it is possible to realize an optical device having good optical performance at the time of image stabilization and focusing on a short distance object.

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 having a fourth lens group having a positive refractive power, wherein the position of the fourth lens group is fixed during zooming, and the first lens group, the second lens group, and the The third lens group is moved along the optical axis, and at the time of focusing, at least a part of the second lens group is moved along the optical axis as a focusing group, and at least the third lens group is moved. A part of the movable group moves so as to include a component in a direction orthogonal to the optical axis, and the in-focus group satisfies the following conditional expression (1). Thereby, it is possible to manufacture a zoom lens with good optical performance during image stabilization and focusing on a short-distance object.
(1) 1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state

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 embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a positive It is composed of a fourth lens group G4 having 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 L11 has an aspheric lens surface on the image side.

The second lens group G2 includes, in order from the object side, a front lens group G2F having a positive refractive power, an aperture stop S, and a rear lens group G2R having a positive refractive power.
The front lens group G2F includes, in order from the object side, a cemented lens of a biconvex positive lens L21 and a negative meniscus lens L22 having a concave surface facing the object side. The positive lens L21 has an aspheric lens surface on the object side.
The rear lens group G2R includes, in order from the object side, a cemented lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.

The third lens group G3 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L31 and a positive meniscus lens L32 having a convex surface facing the object side, and a positive meniscus lens L33 having a convex surface facing the object side. Consists of. The positive meniscus lens L33 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 image 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. In addition, the front lens group G2F, the aperture stop S, and the rear lens group G2R of the second lens group G2 move together during zooming.

In the zoom lens according to the present embodiment, the front lens group G2F in the second lens group G2 is moved to the image side along the optical axis as a focusing group, thereby focusing from an object at infinity to a near object. Do.
In the zoom lens according to the present example, the cemented negative lens of the negative lens L31 and the positive meniscus lens L32 in the third lens group G3 is moved as a movable group so as to include a component in a direction orthogonal to the optical axis. Shake.

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
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 are aspheric 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. D represents the distance from the object to the first surface.
[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 this 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 ∞

1 127.823 0.800 1.697 55.460
* 2 11.015 3.364
3 249.878 0.800 1.619 63.854
4 12.719 1.000
5 15.555 2.315 2.001 29.134
6 37.962 Variable

* 7 17.826 2.087 1.498 82.570
8 -12.421 0.800 1.517 52.203
9 -33.195 Variable
10 (Aperture S) ∞ 2.900
11 15.617 0.800 1.699 30.130
12 8.749 2.400 1.498 82.570
13 -25.039 Variable

14 -60.716 0.800 1.569 56.000
15 10.165 1.000 1.699 30.130
16 13.712 1.048
17 102.788 0.800 1.498 82.570
* 18 250.000 variable

19 ∞ 2.350 1.553 71.683
* 20 -21.305 BF

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8
2 0.000E + 00 -6.935E-05 -1.472E-07 -7.614E-09
7 0.000E + 00 -6.523E-05 2.535E-07 -2.839E-09
18 0.000E + 00 2.082E-04 1.445E-06 3.415E-09
20 0.000E + 00 -3.855E-05 -1.261E-07 4.782E-10

[Various data]
Scaling ratio 2.83

W T
f 10.3 29.1
FNO 3.56 5.66
2ω 77.0 ° 31.4 °
Y 8.19 8.19

(When focusing on an object at infinity)
W M T
f 10.300 20.242 29.100
d6 18.901 5.553 0.724
d9 5.530 5.530 5.530
d13 2.512 6.507 10.439
d18 0.994 7.638 11.048
BF 12.834 12.841 12.834
TL 51.200 48.491 51.003

(When focusing on a short distance object)
W M T
D 200.000 200.000 200.000
d6 22.153 7.145 2.321
d9 2.277 3.937 3.932
d13 2.512 6.507 10.439
d18 0.994 7.638 11.048
BF 12.834 12.841 12.834
TL 51.200 48.491 51.003

[Lens group data]
Group start surface f
1 1 -15.571
2 7 15.500
3 14 -22.390
4 19 38.505

[Anti-vibration data]
W M T
f 10.300 20.242 29.100
Z 0.151 0.185 0.239
θ 0.624 0.500 0.500
K 0.742 0.952 1.060

[Conditional expression values]
(1) | f2f / fw | = 2.358
(2) | f3vr / fw | = 2.039
(3) m12 / fw = 1.765

  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 0.624 ° rotational blur 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. 7 is a coma aberration diagram when the object is in focus, and a coma aberration diagram when the image stabilization is performed for a rotational shake of 0.500 ° when an object at infinity is focused in the telephoto end state. 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 represents the d-line (wavelength 587.6 nm), g represents the g-line (wavelength 435.8 nm), C represents the C-line (wavelength 656.3 nm), F represents the aberration in the F-line (wavelength 486.1 nm), d , G, C, and F do not indicate aberrations in 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 embodiment has high optical performance in which various aberrations are well corrected from the wide-angle end state to the telephoto end state, and when focusing on a short distance object, particularly in the telephoto end state. It can be seen that the optical performance at the time of focusing on a short distance object is good, and that the optical performance is also high at the time of vibration isolation.

(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 embodiment includes a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G3 having a negative refractive power, and a positive It is composed of a fourth lens group G4 having 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 L11 has an aspheric lens surface on the image side.

The second lens group G2 includes, in order from the object side, a front lens group G2F having a positive refractive power, an aperture stop S, and a rear lens group G2R having a positive refractive power.
The front lens group G2F includes, in order from the object side, a cemented lens of a biconvex positive lens L21 and a negative meniscus lens L22 having a concave surface facing the object side. The positive lens L21 has an aspheric lens surface on the object side.
The rear lens group G2R includes, in order from the object side, a cemented lens of a negative meniscus lens L23 having a convex surface facing the object side and a biconvex positive lens L24.

The third lens group G3 includes, in order from the object side, a cemented negative lens of a biconcave negative lens L31 and a positive meniscus lens L32 having a convex surface facing the object side, and a positive meniscus lens L33 having a convex surface facing the object side. Consists of. The positive meniscus lens L33 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 image 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. In addition, the front lens group G2F, the aperture stop S, and the rear lens group G2R of the second lens group G2 move together during zooming.

In the zoom lens according to the present embodiment, the rear lens group G2R in the second lens group G2 is moved to the object side along the optical axis as a focusing group, thereby focusing from an object at infinity to a near object. I do.
In the zoom lens according to the present example, the cemented negative lens of the negative lens L31 and the positive meniscus lens L32 in the third lens group G3 is moved as a movable group so as to include a component in a direction orthogonal to the optical axis. Shake.
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 91.922 0.800 1.697 55.460
* 2 10.780 4.956
3 2408.220 0.800 1.619 63.854
4 13.534 1.000
5 16.091 1.818 2.001 29.134
6 39.382 Variable

* 7 15.457 2.391 1.498 82.570
8 -13.741 0.800 1.517 52.203
9 -31.043 3.409
10 (Aperture S) ∞ Variable
11 18.962 0.800 1.699 30.130
12 8.769 2.400 1.498 82.570
13 -25.955 Variable

14 -62.446 0.800 1.569 56.000
15 9.599 1.000 1.699 30.130
16 13.435 1.048
17 88.765 0.800 1.498 82.570
* 18 250.347 Variable

19 ∞ 2.350 1.553 71.683
* 20 -20.694 BF

Image plane ∞

[Aspherical data]
Surface number κ A4 A6 A8
2 0.000E + 00 -6.263E-05 -1.117E-07 -7.496E-09
7 0.000E + 00 -7.287E-05 -3.487E-07 8.951E-09
18 0.000E + 00 1.799E-04 1.903E-06 -2.343E-08
20 0.000E + 00 -3.123E-05 -2.323E-07 9.786E-10

[Various data]
Scaling ratio 2.83

W T
f 10.3 29.1
FNO 3.56 5.66
2ω 77.0 ° 31.4 °
Y 8.19 8.19

(When focusing on an object at infinity)
W M T
f 10.300 20.147 29.100
d6 18.756 5.704 0.646
d10 3.856 3.856 3.856
d13 2.405 6.528 11.193
d18 1.010 7.525 9.843
BF 12.849 12.864 12.834
TL 51.199 48.786 50.710

(When focusing on a short distance object)
W M T
D 200.000 200.000 200.000
d6 18.756 5.704 0.646
d10 3.343 2.550 1.380
d13 2.917 7.835 13.669
d18 1.010 7.525 9.843
BF 12.849 12.864 12.834
TL 51.199 48.786 50.710

[Lens group data]
Group start surface f
1 1 -15.498
2 7 15.500
3 14 -22.802
4 19 37.401

[Anti-vibration data]
W M T
f 10.300 20.147 29.100
Z 0.152 0.187 0.250
θ 0.624 0.500 0.500
K 0.739 0.943 1.016

[Conditional expression values]
(1) | f2f / fw | = 2.966
(2) | f3vr / fw | = 2.039
(3) m12 / fw = 1.758

  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 image stabilization against 0.624 ° rotational blur 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. 7 is a coma aberration diagram when the object is in focus, and a coma aberration diagram when the image stabilization is performed for a rotational shake of 0.500 ° when an object at infinity is focused 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 embodiment has high optical performance in which various aberrations are well corrected from the wide-angle end state to the telephoto end state, and when focusing on a short distance object, particularly in the telephoto end state. It can be seen that the optical performance at the time of focusing on a short distance object is good, and that the optical performance is also high at the time of vibration isolation.

  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 good optical performance when focusing on a short-distance object. 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, in order to focus from an object at infinity to an object at a short distance, in the optical axis direction with a part of the lens group, the entire lens group, or a plurality of lens groups as the focusing group. It is good also as a structure to which it moves. In particular, it is preferable that at least a part of the second lens group is a focusing 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 third 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 as the photographing lens 2 in the camera 1 is a zoom lens having good optical performance when focusing on a short-distance object. Therefore, the camera 1 can realize good optical performance when focusing on a short-distance object. 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 having a lens group and a fourth lens group having a positive refractive power, and includes the following steps S1 to S4.

  Step S1: The first to fourth lens groups are arranged in order from the object side in the lens barrel, and a known moving mechanism is provided in the lens barrel, thereby fixing the position of the fourth lens group at the time of zooming. Thus, the first to third lens groups are moved along the optical axis.

Step S2: By providing a known moving mechanism in the lens barrel, etc., at the time of focusing, at least a part of the second lens group moves along the optical axis as a focusing group.
Step S3: By providing a known moving mechanism in the lens barrel, at least a part of the third lens group moves as a movable group so as to include a component in a direction perpendicular to the optical axis.

Step S4: The in-focus group satisfies the following conditional expression (1).
(1) 1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state

  According to such a zoom lens manufacturing method of the present application, it is possible to manufacture a zoom lens with good optical performance during image stabilization and focusing on a short-distance object.

G1 First lens group G2 Second lens group G2F Front lens group G2R Rear lens group G3 Third lens group G4 Fourth lens group S Aperture stop I Image surface

Claims (5)

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 A 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,
During focusing, at least a part of the second lens group moves along the optical axis as a focusing group,
Moving so that at least a part of the third lens group includes a component in a direction orthogonal to the optical axis as a movable group;
A zoom lens satisfying the following conditional expression:
1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.00 <| f3vr / fw | <5.00
However,
f3vr: focal length of the movable group fw: focal length of the zoom lens in the wide-angle end state The zoom lens according to claim 1, wherein the following conditional expression is satisfied.
1.00 <m12 / fw <2.50
However,
m12: Distance on the optical axis from the most image-side lens surface in the first lens group to the most object-side lens surface in the second lens group upon zooming from the wide-angle end state to the telephoto end state Change amount fw: focal length of the zoom lens in the wide angle end   An optical apparatus comprising the zoom lens according to any one of claims 1 to 3. 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 A zoom lens manufacturing method comprising:
During zooming, the position of the fourth lens group is fixed, and the first lens group, the second lens group, and the third lens group move along the optical axis,
At the time of focusing, at least a part of the second lens group moves along the optical axis as a focusing group,
At least a part of the third lens group moves as a movable group so as to include a component in a direction orthogonal to the optical axis;
A method of manufacturing a zoom lens, wherein the focusing group satisfies the following conditional expression:
1.50 <| f2f / fw | <3.50
However,
f2f: focal length of the focusing group fw: focal length of the zoom lens in the wide-angle end state

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