JPH11202201A - Zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of constitutive lens groups, to make compact the full length of a wide-angle terminal and to enable camera shake correction by performing the focusing from the infinity to a proximate point by moving a fourth group to the side of an object. SOLUTION: A Gr1 is composed of a concave negative meniscus lens on the image surface side, convex positive meniscus lens on the object side and both convex positive lenses. A GrA of a Gr2 is composed of a concave negative meniscus lens on the image surface side, both concave negative lenses and convex positive meniscus lens on the object side, and a GrB is composed of a concave negative meniscus lens on the image surface side and both convex positive lenses. A Gr3 is composed of both concave negative lenses and both convex positive lenses, a Gr4 is composed of both convex positive lenses, both concave negative lenses, both convex positive lenses and convex positive meniscus lens on the object side, and a focus group is composed of three lenses from the object side. A Gr5 is composed of a concave negative meniscus lens on the image surface side and a joint lens composed of both concave negative lenses and both convex positive lenses.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens, and more particularly, to a compact inner focus type having a camera shake correction function for preventing image shake due to camera shake (for example, vibration during hand-held shooting of a camera). It relates to a telephoto zoom lens.

[0002]

2. Description of the Related Art The mainstream of a focusing system conventionally used in a telephoto zoom lens is a one-group extension system. However, since the first lens group has a large lens weight, this method places a heavy burden on the lens driving motor. In order to avoid this, various types of focusing methods have been proposed.

For example, Japanese Patent Laying-Open No. 3-225307 proposes a focusing system in which a fourth unit is moved in focus in a five-group configuration of positive, negative, positive, positive, and negative. JP-A-3-225308 and JP-A-3-225
Japanese Patent Publication No. 309 proposes a focusing method in which two or more lens groups are moved in focus in a five-group configuration of positive, negative, positive, positive, and negative. JP-A-8-29684
In the official gazette, in the five-group configuration of positive, negative, positive, positive, and negative,
A focusing method has been proposed in which a part of the positive fourth unit is moved in focus.

[0004]

Problems to be Solved by the Invention
The zoom lens proposed in Japanese Patent Publication No. 7 has a configuration in which a fourth unit, which is a focusing unit, does not move during zooming. Therefore, in the focusing method proposed in this publication, it is necessary to secure a sufficient space between the fourth group and the front and rear groups in order to secure a moving margin of the fourth group during focusing. In particular, there is a problem that it is difficult to make the zoom lens compact at the wide-angle end where the distance between the lens units is the smallest. Further, according to the focus methods proposed in JP-A-3-225308, JP-A-3-225309 and JP-A-8-29684, there is a problem that the lens barrel configuration becomes complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and aims to reduce the number of lens groups as much as possible and to enable focusing by moving a certain group. Simplified configuration,
It is an object of the present invention to provide a zoom lens having a compact overall wide-angle end and capable of correcting camera shake.

[0006]

In order to achieve the above object, a zoom lens according to a first aspect of the present invention comprises, in order from the object side, a first group having a positive power, a second group having a negative power, Including a third unit having positive or negative power and a fourth unit having positive power, the first, third and fourth units move toward the object side during zooming from the wide-angle end to the telephoto end. A zoom lens that performs focusing from infinity to proximity by moving the fourth unit toward the object side.

A zoom lens according to a second aspect of the present invention is characterized in that, in the configuration of the first aspect, the following conditional expression is further satisfied. 0.3 <LBw / fw <0.8 where LBw is the distance from the last lens surface to the image plane at the wide-angle end, and fw is the focal length of the entire system at the wide-angle end.

The zoom lens according to a third aspect of the present invention is the zoom lens according to the second aspect of the invention, wherein, in order from the object side, a first group having a positive power, a second group having a negative power, and a positive or negative lens. The zoom lens includes a third lens unit having power, a fourth lens unit having positive power, and a fifth lens unit having negative power. The first lens unit and the third lens unit during zooming from the wide-angle end to the telephoto end. A zoom lens in which a group and a fourth group move to the object side, wherein an image plane correction at the time of camera shake is performed by moving a part of the second group in a direction perpendicular to an optical axis. I do.

In a zoom lens according to a fourth aspect of the present invention, in the configuration of the second aspect, the second group is divided into a negative front group and a positive rear group in order from the object side, and the front group is formed by an optical axis. The image plane is corrected when the camera shake occurs by moving the image plane in the vertical direction.

A zoom lens according to a fifth aspect of the present invention includes, in order from the object side, a first unit having a positive power, a second unit having a negative power, a third unit having a positive or negative power, and a positive unit. A fourth unit having a negative power and a fifth unit having a negative power. In zooming from the wide-angle end to the telephoto end, the first, second, and third groups move toward the object side. A moving zoom lens, characterized by satisfying the following conditional expression. 0.1 <| M2 / M1 | <0.6, where M1: a zoom movement amount of the first lens unit from the wide-angle end to the telephoto end, and M2: a zoom movement amount of the second lens unit from the wide-angle end to the telephoto end.

A zoom lens according to a sixth aspect of the present invention is characterized in that, in the configuration of the fifth aspect, the following conditional expression is further satisfied. 0.30 <Tw / ft <0.55 0.05 <| f2 / f3 | <0.70 where Tw: distance from the first lens surface to the image plane at the wide-angle end, ft: focal length of the entire system at the telephoto end, f2: second The focal length of the second group, f3: the focal length of the third group.

According to a seventh aspect of the present invention, in the zoom lens system according to the sixth aspect of the present invention, focusing from infinity to close proximity is performed by moving the fourth unit to the object side.

According to an eighth aspect of the present invention, in the zoom lens system according to the sixth aspect of the present invention, a part of the second group is moved in a direction perpendicular to an optical axis to perform image plane correction when camera shake occurs. It is characterized by the following.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a zoom lens embodying the present invention will be described with reference to the drawings. 1 to 3 are lens configuration diagrams respectively corresponding to the zoom lenses according to the first to third embodiments, and show the lens arrangement at the wide-angle end [W]. Arrow mi (i = 1, 2, 3, ...) in each lens configuration diagram
Respectively schematically shows movement of the i-th lens unit (Gri) during zooming from the wide-angle end [W] to the telephoto end [T]. Also, in each lens configuration diagram, the surface with ri (i = 1, 2, 3, ...) is the i-th surface counted from the object side, and di (i = 1, 2, 3, 3, ...)
The distance between the top surfaces of the groups marked with
The variable interval that changes in zooming, focusing, and camera shake correction among the third axial upper surface intervals. In the lens configuration diagram, the arrow mD indicates the parallel eccentricity of the camera shake correction group.
{Ie, movement in a direction perpendicular to the optical axis (AX)}, and the arrow mF indicates the focus movement of the focus group.

In the first to third embodiments, in order from the object side, a first lens unit (Gr1) having positive power, a second lens unit (Gr2) having negative power, and a positive or negative power The third with
This is a telephoto zoom lens composed of five groups: a group (Gr3), a fourth group (Gr4) having positive power, and a fifth group (Gr5) having negative power. As shown by arrows m1 to m5 in each lens configuration diagram, in the zooming from the wide-angle end [W] to the telephoto end [T], in the first embodiment, the first unit (Gr1) and the third unit (Gr1) are used. Gr
3) to the fifth lens unit (Gr5) move toward the object side, and the second lens unit (Gr2) is fixed, but in the second and third embodiments, the first lens unit (Gr1)
-The fifth unit (Gr5) moves to the object side.

Focusing from infinity to proximity is performed as shown by the arrow mF, as a whole of the fourth lens unit (Gr4) (second and third embodiments) or a part of the fourth lens unit (Gr4) (first lens unit). Embodiment)
This is performed by moving the object side along the optical axis (AX). The second group (Gr2) is a negative front group (GrA) in order from the object side.
And the positive rear group (GrB), and by moving the front group (GrA) eccentrically perpendicular to the optical axis (AX) as shown by the arrow mD, image plane correction at the time of camera shake occurs ( That is, camera shake correction) is performed.

The first embodiment is a five-group zoom lens of positive, negative, positive, positive, and negative, and each group is configured as follows from the object side. The first group (Gr1) includes a negative meniscus lens concave on the image surface side, a positive meniscus lens convex on the object side, and a biconvex positive lens. Second group
The front group (GrA) of (Gr2) includes a negative meniscus lens concave on the image plane side, a biconcave negative lens, and a positive meniscus lens convex on the object side. The rear group (GrB) of the second group (Gr2)
It is composed of a negative meniscus lens concave on the image plane side and a biconvex positive lens. The third unit (Gr3) includes a biconcave negative lens and a biconvex positive lens. Group 4 (G
r4) is composed of a biconvex positive lens, a biconcave negative lens, a biconvex positive lens, and a positive meniscus lens convex to the object side. (Convex positive / biconcave negative / biconvex positive) constitutes a focus group. Group 5 (Gr
5) is composed of a negative meniscus lens concave on the image plane side, and a cemented lens composed of a biconcave negative lens and a biconvex positive lens.

The second embodiment is a positive, negative, positive, positive, and negative five-group zoom lens, and each group is configured as follows from the object side. The first group (Gr1) includes a cemented lens including a negative meniscus lens concave on the image surface side and a positive meniscus lens convex on the object side, and a positive meniscus lens convex on the object side. Group (GrA) before Group 2 (Gr2)
Is composed of a negative meniscus lens concave on the image plane side, and a cemented lens composed of a biconcave negative lens and a positive meniscus lens convex on the object side. Second group (Gr2) Rear group (GrB)
Is composed of a negative meniscus lens concave on the image plane side and a biconvex positive lens. The third unit (Gr3) includes a cemented lens of a biconcave negative lens and a biconvex positive lens. The fourth group (Gr4) is composed of a cemented lens composed of a biconvex positive lens and a negative meniscus lens concave on the object side, and a biconvex positive lens, and focuses on the entire fourth group (Gr4). Make up a group. The fifth unit (Gr5) includes a plano-concave lens concave on the image plane side, and a cemented lens including a biconcave negative lens and a biconvex positive lens.

The third embodiment relates to a five-group positive / negative / negative / positive / negative zoom lens. Each group is configured as follows in order from the object side. The first group (Gr1) includes a cemented lens including a negative meniscus lens concave on the image surface side and a positive meniscus lens convex on the object side, and a positive meniscus lens convex on the object side. Group (GrA) before Group 2 (Gr2)
Is composed of a negative meniscus lens concave on the image plane side, and a cemented lens composed of a biconcave negative lens and a positive meniscus lens convex on the object side. Second group (Gr2) Rear group (GrB)
Is composed of a negative meniscus lens concave on the image plane side and a biconvex positive lens. The third unit (Gr3) includes a cemented lens of a biconcave negative lens and a biconvex positive lens. The fourth group (Gr4) is composed of a cemented lens composed of a biconvex positive lens and a negative meniscus lens concave on the object side, and a biconvex positive lens, and focuses on the entire fourth group (Gr4). Make up a group. The fifth unit (Gr5) includes a biconcave negative lens, and a cemented lens including a biconcave negative lens and a biconvex positive lens.

As in the first to third embodiments, in order from the object side, a first unit (Gr1) having positive power, a second unit (Gr2) having negative power, a positive or negative A third lens unit (Gr3) having a positive power and a fourth lens unit (Gr4) having a positive power. In a zoom lens in which the third lens unit (Gr3) and the fourth lens unit (Gr4) move to the object side, the focusing from infinity to proximity is performed by moving the whole or part of the fourth lens unit (Gr4) to the object side. By doing so, it is possible to realize a telephoto zoom lens capable of focusing with a simple lens barrel configuration.

The zoom configuration including four groups of positive, negative, (positive or negative) and positive on the object side is a basic configuration for realizing a compact telephoto zoom lens. Then, during zooming from the wide-angle end [W] to the telephoto end [W], the first group (Gr1), the third group (Gr3), and the fourth group (Gr4) are moved toward the object side, so that the wide-angle end [W ] Can be shortened as much as possible. In the conventional zoom configuration in which focusing is performed by the first lens unit (Gr1), the load on the lens driving motor increases due to the large lens weight of the first lens unit (Gr1). As in the embodiment, if the whole or a part of the fourth group (Gr4), which is located inside the lens system and has a light weight, is used as the focus group, the load on the motor can be reduced and smooth focusing can be achieved. Can be achieved. In addition, there is an advantage that focusing can be performed using a high-precision and compact piezoelectric element.

The fourth unit (G) used for focusing
r4) desirably includes at least a positive lens and a negative lens in order from the object side. By employing such a configuration, under spherical aberration generated by the first positive lens during focusing from an infinity in-focus condition to a close object can be corrected by the rear negative lens, Good proximity performance can be ensured. Further, when the positive lens is a biconvex lens and the negative lens is a biconcave lens, it is possible to more effectively correct the spherical aberration.

As described above, the four groups of positive, negative, (positive or negative) and positive are included on the object side, and during zooming from the wide-angle end [W] to the telephoto end [T], the first group (Gr1), Group 3 (Gr3) and Group 4
(Gr4) moves to the object side, and focusing from infinity to proximity is performed by moving all or part of the fourth group (Gr4) to the object side.
It is desirable to satisfy (1). 0.3 <LBw / fw <0.8 (1) where LBw is the distance from the last lens surface to the image plane at the wide-angle end [W], and fw is the focal length of the entire system at the wide-angle end [W].

By satisfying conditional expression (1), a compact telephoto zoom lens can be realized. Conditional expression
When the value is below the lower limit of (1), the lens back at the wide-angle end [W] becomes too short, and cannot be mounted on a single-lens reflex camera that requires a constant lens back. Also, wide-angle end
The focal length at [W] becomes too long, and a sufficient focal length cannot be secured. Conversely, when the value exceeds the upper limit of conditional expression (1), the lens back at the wide-angle end [W] becomes too large, and the overall length is increased. In addition, the focal length at the wide-angle end [W] becomes too short, and the amount of movement of each unit increases due to an increase in the zoom ratio, thereby causing an increase in the overall length.

Further, as in the first to third embodiments,
In order from the object side, a positive first lens unit (Gr1) and a negative second lens unit (Gr2)
And a third group (Gr3) of positive or negative, a fourth group (Gr4) of positive, and a fifth group (Gr5) of negative, and the wide-angle end [W] to the telephoto end [T Group (Gr1), third group in zooming to]
In the zoom lens in which the (Gr3) and the fourth group (Gr4) move to the object side, the image plane correction at the time of camera shake occurs is performed by the second group (Gr2).
To move a part of the lens vertically to the optical axis (AX)
(That is, parallel eccentricity), it is possible to suppress the performance deterioration when camera shake occurs.

From the viewpoint of the effective diameter, it is desirable to perform camera shake correction in a zoom group closer to the object side. This is because, in order to secure the image plane illuminance and the F-number, it is necessary to raise the effective diameter of the lens group located on the object side of the camera shake correction group by twice the moving amount of the camera shake correction group. For example, if camera shake correction is performed in the zoom group on the most image plane side, the effective diameter of all zoom groups must be increased, so that the zoom lens does not increase in the lens radial direction. This is against compactness. If the first group (Gr1) is used to perform camera shake correction, it is advantageous in terms of the effective diameter, but since the lens weight of the first group (Gr1) is large, a large load is applied to the lens driving motor. Become. For the reasons described above, it is desirable to perform the camera shake correction on a part of the second lens unit (Gr2) that is relatively small in lens weight and close to the object plane.

Further, as in the first to third embodiments,
The negative second group (Gr2) is divided into a negative front group (GrA) and a positive rear group (GrB) in order from the object side, and the camera shake correction is performed by parallel eccentricity of the front group (GrA). Then, the burden on the lens driving motor is reduced as compared with the case where the camera shake correction is performed for the entire second lens unit (Gr2), so that a telephoto zoom lens with a camera shake correction function with good total balance can be realized. If the front group (GrA) as the camera shake correction group is composed of two negative lens groups, good camera shake performance can be obtained. If the image-side negative lens unit is formed by joining a biconcave lens and a positive meniscus lens convex on the object side, better performance can be ensured.

Further, as in the first to third embodiments,
In order from the object side, a positive first lens unit (Gr1) and a negative second lens unit (Gr2)
And a third group (Gr3) of positive or negative, a fourth group (Gr4) of positive, and a fifth group (Gr5) of negative, and the wide-angle end [W] to the telephoto end [T Group (Gr1), second group in zooming to]
In the zoom lens in which (Gr2) and the third lens unit (Gr3) move to the object side, it is preferable that the following conditional expression (2) is satisfied. 0.1 <| M2 / M1 | <0.6 (2) where, M1: the amount of zoom movement of the first lens unit (Gr1) from the wide-angle end [W] to the telephoto end [T], M2: telephoto from the wide-angle end [W] The amount of zoom movement of the second lens unit (Gr2) to the end [T].

By satisfying conditional expression (2), a compact telephoto zoom lens can be realized. Conditional expression
When the value falls below the lower limit of (2), the zoom movement amount of the first group (Gr1) becomes too small, and the pressure angle of the cam constituting the first group (Gr1) becomes large. Cannot be moved smoothly. Also, the amount of movement of the second lens unit (Gr2) becomes too small, and particularly, the middle lens unit starts moving from the wide-angle end [W] to the middle.
In the region over [M], it becomes difficult to secure the surrounding illuminance. On the other hand, when the value exceeds the upper limit of the conditional expression (2), the interval between the first and second lens groups at the telephoto end [T] becomes too small.
Since the incident height of the on-axis light at [T] increases, the second group
It becomes difficult to properly correct spherical aberration in (Gr2). In addition, there arises a problem that the first lens unit (Gr1) and the second lens unit (Gr2) interfere at the telephoto end [T].

As described above, positive, negative, (positive or negative), positive,
A zoom lens composed of five negative groups, in which the first group (Gr1), the second group (Gr2), and the third group (Gr3) move toward the object side during zooming from the wide-angle end [W] to the telephoto end [T]. It is desirable to satisfy the following conditional expressions (3) and (4). 0.30 <Tw / ft <0.55 (3) 0.05 <| f2 / f3 | <0.70 (4) where Tw: distance from the first lens surface to the image plane at the wide-angle end [W], ft: telephoto end The focal length of the entire system at [T], f2: focal length of the second group (Gr2), f3: focal length of the third group (Gr3).

By satisfying conditional expressions (3) and (4), it is possible to realize a telephoto zoom lens having a very short overall length, especially at the wide-angle end [W]. If the lower limit of conditional expression (3) is exceeded, the total length at the wide-angle end [W] becomes too short, and it becomes impossible to secure desired optical performance especially at the telephoto end [T].
Conversely, when the value exceeds the upper limit of conditional expression (3), the focal length at the telephoto end [T] becomes too short, and a desired zoom ratio cannot be secured. On the other hand, when the value goes below the lower limit of conditional expression (4), the power of the second lens unit (Gr2) becomes too strong, and
It becomes difficult to correct spherical aberration in (Gr2), especially on the over side. Conversely, when the value exceeds the upper limit of conditional expression (4), the third lens unit
The power of (Gr3) becomes too strong, and it becomes difficult to correct coma aberration, especially at the wide-angle end [W].

The zoom lens system includes five groups: positive, negative, (positive or negative), positive, and negative. The first group (Gr1) and the second group (Gr1) in zooming from the wide-angle end [W] to the telephoto end [T]. Focusing from infinity to close by moving the fourth group (Gr4) to the object side also for the aforementioned zoom lens, which is characterized in that the second lens group (Gr2) and the third group (Gr3) move to the object side. It is desirable to perform camera shake correction by decentering a part of the second lens unit (Gr2) in parallel. This is because, as described above, the burden on the lens driving motor can be reduced without violating compactness.

Each of the zoom units constituting the first to third embodiments is constituted only by a refraction lens which deflects an incident light beam by refraction, but is not limited to this.
For example, each zoom group may be configured by a diffractive lens that deflects an incident light beam by diffraction, a refraction / diffraction hybrid lens that deflects an incident light beam by a combination of a diffraction action and a refraction action, or the like.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The zoom lens according to the present invention will be described more specifically with reference to construction data, aberration diagrams, and the like. Examples 1 to 3 given here as examples correspond to the above-described first to third embodiments, respectively.
1 to 3 showing the third embodiment are the same as those of the first to third embodiments.
1 shows the lens configuration at the wide-angle end [W].

In the construction data of each embodiment, ri (i = 1, 2, 3,...) Is the radius of curvature of the i-th surface counted from the object side, and di (i = 1, 2, 3,. ..) is the i-th shaft upper surface distance counted from the object side (shown here before the eccentricity), which is changed by zooming (variable space).
Is the actual surface distance between each group from the wide-angle end [W] to the intermediate focal length state (middle) [M] to the telephoto end [T]. Also, Ni (i =
1,2,3, ...) and νi (i = 1,2,3, ...) are i
Refractive index (Nd), Abbe number for the d-line of the second lens
(νd). The focal length f and the F-number FNO of the entire system corresponding to each focal length state [W], [M], [T] are shown together with other data, and Table 1 shows the values corresponding to the conditional expressions of each embodiment. .

[0036]

[Proximity Data] Wide-angle end [W]: β = -0.056, d20 = 1.000, d26 = 2.253 Telephoto end [T]: β = -0.197, d20 = 1.000, d26 = 8.773

[0038]

[Proximity data] Wide-angle end [W]: β = -0.060, d17 = 3.986, d22 = 26.024 Telephoto end [T]: β = -0.192, d17 = 3.021, d22 = 8.700

[0040]

[Proximity Data] Wide-angle end [W]: β = −0.053, d17 = 1.000, d22 = 17.962 Telephoto end [T]: β = -0.192, d17 = 1.000, d22 = 5.515

[0042]

[Table 1]

4 to 9 show the aberration performance before decentering (normal state) of each embodiment. 4 to 6 are longitudinal aberration diagrams of the first to third embodiments before decentering (normal state) and in infinity shooting, and FIGS. 7 to 9 are decentering of the first to third embodiments. Previous,
FIG. 4 is a longitudinal aberration diagram in a close-up shooting state (a close-up object distance of 1.5 m). 4 to 9, [W] denotes a wide-angle end, [M] denotes an intermediate focal length state (middle), and [T] denotes various aberrations at a telephoto end (in order from the left, spherical aberration, astigmatism, distortion; Y ′: image height), solid line (d) is aberration for d-line, dashed line (g) is aberration for g-line, two-dot chain line (c) is aberration for c-line, broken line
(SC) indicates a sine condition, and a dashed line (DM) and a solid line (D
S) represents astigmatism with respect to d-line on the meridional surface and the sagittal surface, respectively.

FIGS. 10 to 18 show the aberration performance of each embodiment in an infinity photographing state before eccentricity (normal state) and after eccentricity (camera shake correction state). 10 to 12 show Embodiment 1 and FIG.
3 to 15 correspond to the second embodiment, and FIGS. 16 to 18 correspond to the third embodiment, respectively. FIGS. 10, 13, and 16 show the wide-angle end [W],
11, 14, and 17 show middle [M], and FIGS. 12, 1
5 and FIG. 18 are lateral aberration diagrams respectively corresponding to the telephoto end [T]. Also, in FIGS. 10 to 18, (A) to (C) show the camera shake correction state of 0.7 degrees (the camera shake correction angle θ = 0.7 ° (= 0.
(D) and (E) in the correction state}
Indicates lateral aberration in a normal state, and (A) indicates an image height Y ′.
= 12, (B) is image height Y '= 0, (C) is image height Y' =-12, and (D) is image height
Y ′ = 12 and (E) show the lateral aberration at the image height Y ′ = 0.

[0045]

As described above, according to the first to eighth aspects of the present invention, a compact zoom lens having high optical performance can be realized.
According to the invention, the total length at the wide-angle end is further reduced, and a telephoto zoom lens of an inner focus system with a simplified lens barrel configuration can be realized. According to the third, fourth, and eighth aspects, it is possible to satisfactorily perform image plane correction when camera shake occurs while minimizing the load on the lens driving motor.

[Brief description of the drawings]

FIG. 1 is a lens configuration diagram of a first embodiment (Example 1).

FIG. 2 is a lens configuration diagram of a second embodiment (Example 2).

FIG. 3 is a lens configuration diagram of a third embodiment (Example 3).

FIG. 4 is a longitudinal aberration diagram of Example 1 in an infinity shooting state before decentering.

FIG. 5 is a longitudinal aberration diagram of Embodiment 2 in an infinity shooting state before decentering.

FIG. 6 is a longitudinal aberration diagram of Example 3 in an infinity shooting state before decentering.

FIG. 7 is a longitudinal aberration diagram in a close-up photographing state before decentering according to the first embodiment.

FIG. 8 is a longitudinal aberration diagram in a close-up photographing state before decentering according to the second embodiment.

FIG. 9 is a longitudinal aberration diagram of the third embodiment before decentering and in a close-up photographing state.

FIG. 10 is a lateral aberration diagram of the first embodiment before and after decentering, at the wide-angle end, and at infinity.

FIG. 11 is a lateral aberration diagram of the first embodiment before and after eccentricity, middle, and infinity shooting.

FIG. 12 is a lateral aberration diagram before and after eccentricity, at a telephoto end, and at infinity in Example 1;

FIG. 13 is a lateral aberration diagram before and after decentering, at a wide-angle end, and at infinity, according to the second embodiment.

FIG. 14 is a lateral aberration diagram before and after eccentricity, middle, and infinity photographing in Example 2.

FIG. 15 is a lateral aberration diagram before and after eccentricity, at a telephoto end, and at infinity shooting state in Example 2.

FIG. 16 is a lateral aberration diagram before and after decentering, at the wide-angle end, and at infinity in Example 3;

FIG. 17 is a lateral aberration diagram before and after eccentricity, middle, and infinity photographing in Example 3.

FIG. 18 is a lateral aberration diagram before and after eccentricity, at a telephoto end, and at infinity in Example 3;

[Explanation of symbols]

 Gr1 ... first group Gr2 ... second group GrA ... front group GrB ... rear group Gr3 ... third group Gr4 ... fourth group Gr5 ... fifth group

Claims (8)

[Claims] 1. A first unit having a positive power, a second unit having a negative power, a third unit having a positive or negative power, and a fourth unit having a positive power, in order from the object side. And the first in zooming from the wide-angle end to the telephoto end.
A zoom lens in which a group, a third group, and a fourth group move toward the object side, wherein focusing is performed from infinity to close proximity by moving the fourth group toward the object side. 2. The zoom lens according to claim 1, further satisfying the following conditional expression: 0.3 <LBw / fw <0.8, where LBw is the distance from the last lens surface to the image plane at the wide-angle end. , Fw: The focal length of the whole system at the wide-angle end. 3. A first unit having a positive power, a second unit having a negative power, a third unit having a positive or negative power, and a fourth unit having a positive power, in order from the object side. And a fifth unit having negative power, wherein the first, third and fourth units move toward the object side during zooming from the wide-angle end to the telephoto end. 3. The zoom lens according to claim 2, wherein an image plane is corrected when a camera shake occurs by moving a part of said second group in a direction perpendicular to an optical axis. 4. An image plane upon occurrence of camera shake by moving the front lens group in a direction perpendicular to the optical axis by dividing the second lens group into a negative front lens group and a positive rear lens group in order from the object side. The zoom lens according to claim 2, wherein the correction is performed. 5. A first unit having a positive power, a second unit having a negative power, a third unit having a positive or negative power, and a fourth unit having a positive power, in order from the object side. And a fifth unit having negative power, wherein the first, second, and third units move toward the object side during zooming from the wide-angle end to the telephoto end. 0.1 <| M2 / M1 | <0.6, where M1: zoom movement amount of the first group from the wide-angle end to the telephoto end, M2: telephoto from the wide-angle end The amount of zoom movement of the second group to the end. 6. The zoom lens according to claim 5, further satisfying the following conditional expression: 0.30 <Tw / ft <0.55 0.05 <| f2 / f3 | <0.70, where Tw: wide-angle end The distance from the first lens surface to the image plane, ft: focal length of the entire system at the telephoto end, f2: focal length of the second lens unit, f3: focal length of the third lens unit. 7. The zoom lens according to claim 6, wherein focusing from infinity to close proximity is performed by moving the fourth group toward the object side. 8. The zoom lens according to claim 6, wherein an image plane is corrected when a camera shake occurs by moving a part of said second group in a direction perpendicular to an optical axis.