JPH06289296A - Zoom lens with vibrationproofing function - Google Patents

Abstract

PURPOSE:To provide a zoom lens with high performance applicable as a lens for general photography and as providing a vibrationproofing function. CONSTITUTION:A zoom lens formed with four lens groups with positive, negative, positive, and positive refracting power and equipped with a vibration proofing image position displacement means which performs vibrationproof by moving a second lens group to an image side and a third lens group G3 in a direction intersecting almost orthogonally to an optical axis at the time of performing variable from power a wide angle end to a telephoto end is comprised so as to satisfy a relation DELTAY= f4/f3.DELTAS assuming the amount of travel in a direction intersecting orthogonally with the optical axis of the 3rd lens group G3 as DELTAS and the focal distance of the third lens group as f3, that of a fourth lens group as f4, and the amount of travel of an image at the time of the variable power as DELTAY.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens having an image stabilizing function.

[0002]

2. Description of the Related Art A conventional zoom lens having an anti-vibration function is disclosed in JP-A-1-189621 and JP-A-1-191.
No. 112 and Japanese Patent Laid-Open No. 1-191113, an arbitrary zoom lens group (especially one group and four groups) of the zoom lens composed of two or more lens groups is crossed across the optical axis for vibration isolation. Displacement is used to correct the image formation state, and
As disclosed in Japanese Patent No. 284823, there is a correction method in which only a part of the first lens group fixed during zooming is moved.

[0003]

However, the above-mentioned conventional techniques are intended to be used for a small camera such as a so-called compact camera, and the following is used for a so-called single lens reflex lens. There is such a problem.

First, if the structure of this prior art is applied as it is to a lens for a single-lens reflex camera, there is a problem that a back focus of a generally required degree cannot be sufficiently obtained. Further, since miniaturization is the most important factor, there is a drawback that a large zoom ratio cannot be realized, and there is a problem that it cannot be applied to a high-performance single lens reflex lens for general photography, a telephoto zoom lens, etc. .

The present invention has been made to solve these problems and is applicable as a lens for general photography, with the object of providing a high-performance zoom lens having an anti-vibration function. There is.

[0006]

In order to solve the above problems, in a zoom lens having an image stabilizing function according to the first aspect of the present invention, a zoom lens having a positive refracting power is arranged in order from the object side. There is one lens group G ₁ , a second lens group G ₂ having a negative refractive power, a third lens group G ₃ having a positive refractive power, and a fourth lens group G ₄ having a positive refractive power. During zooming from the wide-angle end to the telephoto end, the second lens group G ₂ moves toward the image side for zooming, and the third lens group G ₃ moves in a direction substantially orthogonal to the optical axis. Equipped with image position displacement means for image stabilization,
The amount of movement of the third lens group G ₃ in a direction substantially orthogonal to the optical axis is ΔS, the focal length of the third lens group is f ₃ , the focal length of the fourth lens group is f ₄ , and the image at the time of zooming is When the amount of movement is ΔY, the relationship of the following expression (1) is satisfied.

ΔY = f ₄ / f ₃ · ΔS (1) Formula

In the invention described in claim 2 of the present application, claim 1
The zoom lens equipped with the image stabilization function described in (4) has a focal length at the wide-angle end of the zoom lens of f _W and a focal length at the telephoto end of f.
_T , the maximum displacement of the third lens group G _{3 at the time} of vibration isolation is ΔS
_{When max} is set, the conditions of the following expressions (2) and (3) are satisfied.

0.5 <f ₃ / (f _W · f _T ) ^1/2 <1 (2) Formula

ΔS _max / f ₃ <0.1 Equation (3)

According to the invention of claim 3 of the present application, claim 1
Alternatively, the zoom lens 2 having the image stabilizing function described in 2,
A flare stop that blocks unnecessary light when the third lens group G ₃ is moved in a direction substantially orthogonal to the optical axis for vibration isolation is disposed fixed to the optical axis. Is characterized by.

[0012]

The present invention is particularly suitable for a telephoto zoom lens for photography, basically, in order from the object side, positive, negative, positive,
A zoom lens composed of a so-called four-group structure having a positive refracting power is adopted, and a third lens group among them is moved in the direction orthogonal to the optical axis to change the image forming position. It has a mechanism. The features and advantages of this type of zoom lens will be briefly described below.

A telephoto zoom lens for photography is mainly a zoom type having four groups of positive, negative, positive, and positive. A typical type is three groups on the object side, an afocal zoom lens.
This is a type that configures a computer and will be described by taking this as an example.

This four-group zoom type is a four-group construction consisting of lens groups having positive, negative, positive and positive refracting power from the object side. The second lens group has a variable power effect and the third lens group has an image surface. Has the effect of correcting the movement of the. Further, during zooming, the second lens group and the third lens group move, and the third lens group-the fourth lens group
The ray bundles between the lens groups are parallel, and the first lens group and the fourth lens group are fixed.

The zoom lens according to this system has a variable power ratio of up to about 4 and has a good image forming performance. In addition, in terms of the mechanism, the number of movable groups during zooming is small, and if focusing is performed by the first lens group or the fourth lens group, it can be separated from the lens group used during zooming. There is. Therefore, the four-group zoom lens type has been widely used for the telephoto zoom lens.

The present invention relates to an improvement of such a four-group zoom lens type and has found optimum conditions as a zoom lens having a vibration-proof function. In particular, the third lens group is a vibration-proof group. The details of the construction of the anti-vibration zoom lens and the conditions therefor will be described below.

First, as a method of stabilizing the image stabilizing zoom lens according to the present invention, a method of shifting the lens group or the lens in a direction substantially orthogonal to the optical axis is adopted. That is, the image-forming position is changed by moving the lens group or lens inside the optical system by an appropriate amount in the direction substantially orthogonal to the optical axis to shift the entire optical axis due to camera shake, etc. This is a method of correcting the amount.

Next, a lens group or a lens that is shifted during image stabilization will be described. In a typical telephoto zoom lens, the first lens group is the largest lens group, and
It is often extended (moved to the object side) when performing caching. Therefore, it is not preferable to use a correction optical system that displaces the first lens group with respect to the optical axis for image stabilization because the size becomes further large when the holding mechanism and the drive mechanism are added.

The fourth lens group has a relatively long overall length,
Since the lens diameter is also large, the holding mechanism and the driving mechanism also become large, which is not preferable. Therefore, even in the positive, negative, positive, positive four-group zoom type according to the present invention, similarly, it is not preferable to use the first lens group and the fourth lens group as a correction optical system for image stabilization.

Next, when the second lens group and the third lens group are compared and examined, they are common in that the lens groups are small, but as described above, in the four-group afocal type, the third lens group is used. It is characteristic that the magnification in the group is infinite and constant during zooming, in other words, the third lens group always works to emit parallel rays during zooming.

Therefore, the focal length becomes larger than that of the second lens group, and the apparent F number becomes darker. Therefore, the third lens group has a simpler lens structure than the second lens group. Is possible. In addition, the decentering of the lens, which is one of the lens manufacturing errors, is generally less affected by the third lens group on the imaging characteristics. Are suitable. In addition, the lens group near the aperture stop has a relatively small lens diameter because the bundles of light rays at each angle of view are densely gathered.

Therefore, even if a correction optical system is added to such a third lens group with an anti-vibration function and is displaced with respect to the optical axis, the holding mechanism and the drive mechanism do not increase in size, so the correction system Since it is possible to simplify the entire configuration including the above, it is convenient to use as an anti-vibration lens group even from the demand for miniaturization. Further, in terms of aberration, the third lens group can correct the image position without making a large difference in image quality change between the central portion and the peripheral portion.

From the above, the present invention has found that it is optimal to use the third lens group as the image stabilizing group.

In addition, in the above structure, if the amount of movement of the third lens group in the direction substantially perpendicular to the optical axis is ΔS and the amount of movement of the image at this time is ΔY, then the following (1) The relation of formula is established, and the movement amount at that time is constant regardless of the zoom position.

ΔY = f ₄ / f ₃ · ΔS (1) Formula

Equation (1) indicates that the amount of movement of the third lens group is determined by the lateral magnification of the composite of the third lens group and the fourth lens group. Then, this condition is a condition that is satisfied in the case of the above-mentioned four-group afocal type, and it is clear from this condition that the present invention is particularly suitable for this type of zoom lens.

Further, when the lens group is displaced in the direction substantially orthogonal to the optical axis for the image stabilization operation, a light beam unnecessary for image formation is transmitted from the optical axis of the image stabilization lens group to the peripheral portion,
It may enter the imaging surface. Therefore, by providing a flare diaphragm fixed to the optical axis in addition to the aperture stop of the lens system, such unnecessary light rays in the peripheral portion are effectively blocked.

The position where the flare diaphragm is formed is not particularly limited as long as the unnecessary light in the peripheral portion can be blocked during the vibration-proof movement of the vibration-proof lens group. Is also good.

Next, in the invention described in claim 2, the following conditional expression is satisfied in the above configuration.

0.5 <f ₃ / (f _W · f _T ) ^1/2 <1 (2) Formula

ΔS _max / f ₃ <0.1 (3) Formula

The expression (2) defines an appropriate focal length range of the third lens group to which the image stabilizing function is added.
If the upper limit of expression (2) is exceeded, the focal length of the third lens group becomes too large, and the lens diameter and diaphragm diameter become large, which violates the demand for downsizing. In addition, if an aperture stop is arranged in the vicinity of the fourth lens group as in a normal zoom lens, the chief ray is separated from the optical axis in the first lens group, so that the lens diameter is also increased and the front lens diameter is increased. It is not preferable because it invites.

On the other hand, when the value goes below the lower limit of the expression (2), the focal length of the third lens group becomes too small, and the distance between the second lens group and the second lens group becomes narrower. It is difficult to secure a sufficient zoom ratio, and it is difficult to secure a sufficient zoom ratio. In addition, the Petzval sum is apt to deviate in the positive direction, and good imaging performance cannot be obtained. In addition,
The condition of the expression (2) is preferably within the range of 0.6 to 0.8, but if it is within the range of the condition of the expression (1), no practical problem occurs.

Expression (3) defines an appropriate range of the maximum movement amount of the third lens group during image stabilization from the relationship (ratio) with the focal length of the third lens group. If the upper limit of expression (3) is exceeded, the amount of movement of the third lens group during image stabilization will become too large,
As a result, the amount of aberration variation during image stabilization becomes too large, making correction difficult. In particular, there is a problem that the difference in the optical axis direction between the best image plane in the m direction and the best image plane in the S direction at the peripheral position on the image plane widens. Also, the mechanism for vibration isolation becomes complicated,
The zoom lens as a whole is likely to be upsized, which goes against the problems in manufacturing and the demand for downsizing. The smaller the condition value of the equation (3), the more preferable, but it is possible to correct the aberration and the like from other design conditions and the like within the range of this condition.

In addition to the above conditions, it is desirable that the vibration-proof zoom lens according to the present invention satisfy the following conditional expression in order to achieve further excellent performance.

[0036] _{0.5 <r t / f 3 <} 20 ... (4) formula

L / f _W <0.3 Equation (5)

Here, r _t is the radius of curvature of the object-side surface of the most image-side convex lens in the third lens group. L is the total length of the image stabilizing lens group (the length measured along the optical axis).

If the range of expression (4) (either the upper limit or the lower limit) is exceeded, fluctuations of spherical aberration and field curvature during zooming,
The fluctuation of astigmatism becomes excessive. Further, even during image stabilization, fluctuations in spherical aberration and coma aberration become excessive, and it becomes difficult to correct aberrations based on this, which is inconvenient.

When the value exceeds the upper limit of the expression (5), the total length of the image stabilizing lens unit becomes long and the weight increases, and the mechanical system for image stabilizing becomes complicated and large in size.

Next, the control system of the image stabilizing mechanism will be described. Blur amount of optical axis considered on the object side of zoom lens ΔW
Is corrected regardless of the zoom position, the focal length of the entire system at an arbitrary zoom position is set to f _Z, and this is indicated by Z times the focal length f _W at the wide-angle end (f _Z = f _W · Z).

[0042] The parameter - Using data Z, at the wide-angle end, when the correction amount △ S _W against vibration angular △ W of the optical axis, any's - displacement of the vibration proof group in home position △
It is necessary to control the correction amount so that S _Z is represented by the following equation (6).

ΔS _Z = ΔS _W · Z (6) Formula

In order to control the anti-vibration mechanism so as to satisfy the expression (6), the rotary encoder is used, for example, in the second lens group or the third lens group so that the above Z can be obtained. It is necessary to have means for reading the rotation angle, etc. Although various other control system algorithms can be considered, the most standard algorithm is shown for each.

When actually constructing the third lens group, it is desirable to have a configuration including at least one convex lens and one concave lens. When the third lens group is composed of one convex lens and one concave lens, these are cemented lenses, and when they are composed of three or more lens groups, the cemented lens is provided on the image side. This reduces variations in various aberrations during image stabilization.

At this time, by making the direction of the cemented surface convex toward the image side, it is possible to suppress the fluctuation of the field curvature and the fluctuation of the astigmatism at the time of zooming, and at the same time, at the time of image stabilization. Variations of various aberrations can also be suppressed.

Further, in order to obtain a good achromat during zooming and image stabilization, and to obtain a zoom lens having excellent imaging performance, the following formulas (7) and (8) are used. It is preferable to satisfy the conditions.

0.1 <Δη _d <0.4 (7) Formula

15 <Δν _d <50 Equation (8)

It should be noted that Δη _d is obtained by subtracting the average value of the refractive index of the convex lens from the average value of the refractive index of the concave lens forming the third lens group, and the average Abbe number of the convex lenses forming the third lens group is defined as Δη _d. Δν _d is obtained by subtracting the average Abbe number of the concave lens from the value.

Equation (7) is a condition for correcting spherical aberration favorably during zooming and during image stabilization, and by satisfying this condition, the Petzval sum of the entire zoom lens is favorably compensated. It is also possible to do. If the range of the expression (7) is exceeded, large spherical aberration occurs, and astigmatism and curvature of the image surface become great, resulting in a problem that good imaging characteristics cannot be obtained.

Equation (8) shows the range of Abbe numbers for favorably achromatizing the third lens group. If it deviates from this range, color shift occurs, which makes it difficult to obtain good imaging characteristics, and it becomes difficult to correct various aberrations.

Further, by adopting an aspherical surface for the lens surface in the third lens group, it is possible to achieve a further excellent imaging performance. In particular, when an aspherical surface is applied to the surface of the third lens group that is closest to the object side, the effect of improving the image forming characteristics becomes great.

As described above, the present invention, in order from the object side,
Z-group consisting of so-called four-group structure with positive and negative positive power
This is a lens with a suitable anti-vibration function added, and if it is additionally stated, it is equipped with an optimal anti-vibration function for a type in which three groups on the object side constitute an afocal-zoom converter.

In order to form a four-group type zoom lens which constitutes such an afocal system, the image position by the first lens group and the second lens group and the object side focal position of the third lens group are spatially separated. By making them coincide with each other, it is possible to form an afocal system between the third lens group and the fourth lens group.

By adopting an anti-vibration mechanism for the third lens group of such an afocal-zoom converter,
It is possible to obtain a zoom lens having an extremely good image forming characteristic and an image stabilization function.

[0057]

The present invention will be described in more detail with reference to the following examples. Each of the embodiments described here has, in order from the object side, a first lens group G ₁ having a positive refracting power, a second lens group G ₂ having a negative refracting power, and a positive refracting power. It has a third lens group G ₃ and a fourth lens group G ₄ having a positive refractive power, and the second lens group G ₄ is used during zooming from the wide-angle end to the telephoto end.
Reference numeral ₂ has an image position displacement means for moving to the image side for zooming, and further for moving the third lens group G ₃ in a direction substantially orthogonal to the optical axis for image stabilization. Three lens group G
The moving amount of ₃ is ΔS, and the focal length of the third lens group G ₃ is f
₃ , the focal length of the fourth lens group is f ₄ , and the image movement amount is ΔY
Then, the following conditions are satisfied.

ΔY = f ₄ / f ₃ · ΔS (1) Formula

Here, three kinds of embodiments of the present invention will be described, but the present invention is applied to a so-called four-group afocal type zoom lens, and the design numerical values and each of these three kinds of embodiments are shown. The corresponding numerical values of the conditions are shown in Table 1 below.

In the table below, the condition defined by the equation (1) is a condition that is always satisfied in the so-called four-group afocal zoom lens, but for reference, only the respective values at the telephoto end and the wide-angle end are shown. Shown in the table. The numerical value is a design value in each of the embodiments, and almost exactly satisfies the condition of the expression (1) although some errors occur. Further, in each of the examples, the vibration control displacement amount of the third lens group is controlled so as to satisfy the expression (6).

[0061]

[Table 1]

Each embodiment according to the present invention will be described below. First, FIG. 1 shows a schematic configuration of the image stabilizing zoom lens according to the first embodiment of the present invention. This example is a typical application of the present invention, the focal length is 100-300 mm,
It is F4.5 (F number).

This embodiment is a zoom lens having a four-group configuration of lens groups G _{1a to} G _4a having positive, negative, positive, and positive refractive power in order from the object side, and when zooming from the wide-angle end to the telephoto end, The lens group G _2a moves toward the image side, and the third lens group G _3a moves nonlinearly. The first lens group G _1a and the fourth lens group G _4a are fixed to a lens barrel (not shown), and the light flux between the third lens group G _3a and the fourth lens group G _4a is The system becomes a parallel system, and the second lens group G _2a has a variable power effect and the third lens group G _3a has a function of correcting the movement of the image plane.

The third lens group G _3a is composed of two combined lenses, a convex lens and a concave lens, and is arranged with its convex surface facing the image side. Further, it is configured so as to be movable in a direction orthogonal to the optical axis, and is provided with control means for detecting a shake or the like of the entire lens system and performing a predetermined displacement. As described above, in this control means, the movement amount is controlled so that the vibration isolation displacement amount of the third lens group G _3a satisfies the above equation (6).

At a position near the object side of the fourth lens group G _4a ,
An aperture stop S ₁ of the image stabilizing zoom lens system according to this embodiment is provided, and a fixed stop FS ₁ is provided on the image side of the aperture stop S ₁ . Separately from this, when the third lens group G _3a is displaced in the direction orthogonal to the optical axis during the image stabilization operation, a flare stop that blocks unnecessary light at a peripheral position away from the optical axis is provided on the optical axis. It is preferable to provide it in a fixed state with respect to.

Table 2 below shows design values of each lens and the like in the first embodiment.

[0067]

[Table 2]

FIG. 2 shows the state of aberration correction in the first embodiment.
(Wide-angle end) and Fig. 3 (Telephoto end). As shown in these figures, according to the present embodiment, each aberration is satisfactorily corrected in any zooming range, and the third lens group G _3a is corrected in the direction orthogonal to the optical axis during the image stabilization operation. Even if it moves, the lateral aberration with respect to the image is suppressed extremely minutely.

Next, a second embodiment of the present invention will be described. In this embodiment, the present invention is applied to a zoom lens on the slightly wide angle side as compared with the first embodiment, and the focal length is 80 to 200 mm and F4.

FIG. 4 shows the schematic constitution of the vibration-proof zoom lens according to this embodiment. As in the above-mentioned embodiment, the four lens unit groups G _{1b to} G _4b having positive, negative, positive and positive refracting power are arranged in order from the object side. The second lens group G _2b moves to the image side during zooming from the wide-angle end to the telephoto end, and the third lens group G
_3b moves non-linearly. The first lens group G _1b and the fourth lens group G _4b are fixed to a lens barrel (not shown), and the light flux between the third lens group G _3b and the fourth lens group G _4b is It becomes a parallel system, and the second lens group G _2b performs the zooming action.
The third lens group G _3b has a function of correcting the movement of the image plane.

The third lens group G _3b in the second embodiment is
It consists of a combination of two lenses, a convex lens and a concave lens, and is arranged with its convex surface facing the image side. further,
It is configured to be movable in a direction orthogonal to the optical axis, and is provided with control means for detecting blurring or the like of the entire lens system and performing control so as to perform predetermined displacement. The vibration isolation displacement amount in this embodiment is controlled so as to satisfy the above equation (6).

At a position near the object side of the fourth lens group G _4b ,
An aperture stop S ₂ of the image stabilizing zoom lens system according to this example is provided, and a fixed stop FS ₂ is provided on the image side of the aperture stop S ₂ . Separately from this, when the third lens group G _3b is displaced in the direction orthogonal to the optical axis during the image stabilization operation, a flare stop that blocks unnecessary light at a peripheral position away from the optical axis is provided on the optical axis. It is preferable to provide it in a fixed state with respect to.

Table 3 below shows design values of each lens and the like in the second embodiment.

[0074]

[Table 3]

FIG. 5 shows the state of aberration correction in the second embodiment.
(Wide-angle end) and FIG. 6 (Telephoto end). As shown in these figures, also in the second embodiment, each aberration is well corrected in any zooming range, and the third lens group G _3b moves in the direction orthogonal to the optical axis during the image stabilizing operation. Even if the correction movement is performed, the lateral aberration with respect to the image is extremely small.

Next, a third embodiment of the present invention will be described. In this embodiment, the present invention is applied to a relatively bright telephoto zoom lens, and the focal length is 80 to 200 m.
m and F2.8.

FIG. 4 shows a schematic structure of the vibration-proof zoom lens according to the third embodiment. As in the above embodiments, lens groups G _{1c to} G _4c having positive, negative, positive and positive refracting powers in order from the object side.
The second lens group G _2c moves toward the image side and the third lens group G _3c moves nonlinearly during zooming from the wide-angle end to the telephoto end. Then, the first lens group G
_1c and the fourth lens group G _4c are fixed to a lens barrel (not shown), the light flux between the third lens group G _3c and the fourth lens group G _4c is a parallel system, and the second lens The group G _2c has a zooming function, and the third lens group G _3c has a function of correcting the movement of the image plane.

The third lens group G _3c of the third embodiment is composed of three lenses, which are a combination lens of a convex lens and a concave lens, and another convex lens, and the convex side of the combination lens is directed to the image side, and the image is formed more than the single convex lens. It is arranged on the side.

Further, the third lens group G _3c is constructed so as to be movable in the direction orthogonal to the optical axis, and the control means for detecting the shake of the entire lens system and performing the predetermined displacement. Is provided. Also in this embodiment, the vibration-proof displacement amount is controlled so as to satisfy the equation (6).

In the third embodiment, the fourth lens group G
_An aperture stop S ₂ is provided in the middle portion of _4c , but apart from this, when the third lens group G _3c is displaced in the direction orthogonal to the optical axis during the image _{stabilization operation} , it is separated from the optical axis. It is advisable to provide a flare stop that blocks unnecessary light at peripheral positions in a state of being fixed with respect to the optical axis.

Table 4 below shows design values of each lens and the like in the third embodiment.

[0082]

[Table 4]

FIG. 8 shows the state of aberration correction in the third embodiment.
(Wide-angle end) and FIG. 9 (Telephoto end). As shown in these figures, in the present embodiment as well, each aberration is well corrected in any zoom range, and the third lens group G is used during the image stabilization operation.
_{Even if 3c} is corrected and moved in the direction orthogonal to the optical axis, lateral aberration with respect to the image is suppressed to an extremely small amount.

In each of the above-described embodiments, the present invention is applied to the zoom lens of the four-group afocal type, so that the magnification of the third lens group is always constant during zooming of the entire zoom lens. Since it forms a parallel relay system with the four lens groups, it is the simplest lens group among all four lens groups.

Therefore, even if the image stabilizing mechanism is provided in the third lens group as in each of the embodiments, the enlargement of the zoom lens system (outer shape) is suppressed, and the structure of the displacement mechanism for image stabilizing is compared. There is an advantage that the configuration is simple.

[0086]

As described above, according to the present invention, in the zoom lens having the image stabilizing function, it is possible to suppress the size increase even if the image stabilizing function is added, and the various aberrations are satisfactorily corrected. It is possible to obtain a high-performance zoom lens having excellent image forming characteristics.

Particularly, the present invention has a so-called four-group structure, and
It is suitable for a zoom lens of the type that forms an afocal zoom converter with three groups, and has an optimum configuration for a so-called telephoto zoom lens for photography.

However, since the first lens group and the fourth lens group are also configured to be movable during zooming, it is possible to increase the zooming cost and to improve the performance of the imaging characteristics during zooming. It can also be applied to the zoom type.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a vibration-proof zoom lens according to a first embodiment of the present invention.

FIG. 2 is an aberration diagram showing states of various aberrations at the wide-angle end in the first example.

FIG. 3 is an aberration diagram showing states of various aberrations at the telephoto end of the first example.

FIG. 4 is an explanatory diagram showing a schematic configuration and the like of a vibration-proof zoom lens according to the present invention.

FIG. 5 is an aberration diagram showing states of various aberrations at the wide-angle end.

FIG. 6 is an aberration diagram showing states of various aberrations at the telephoto end.

FIG. 7 is an explanatory diagram showing a schematic configuration of a vibration-proof zoom lens according to a third embodiment of the present invention.

FIG. 8 is an aberration diagram showing various aberration states at the wide-angle end in the third example.

FIG. 9 is an aberration diagram showing states of various aberrations at the telephoto end of the third example.

[Explanation of symbols]

G ₁ , G _1a , G _1b , G _1c ... First lens group G ₂ , G _2a , G _2b , G _2c ... Second lens group G ₃ , G _3a , G _3b , G _3c ... Third lens group S, S ₁ , S ₂ , S ₃ ... Aperture diaphragm FS ₁ , FS ₂ , FS ₃ ... Fixed diaphragm

Claims (3)

[Claims] 1. A first lens group G ₁ having a positive refractive power and a second lens group G ₂ having a negative refractive power in order from the object side.
And a third lens group G ₃ having a positive refractive power and a fourth lens group G ₄ having a positive refractive power, and the second lens group G ₂ at the time of zooming from the wide-angle end to the telephoto end. There moves toward the image side for zooming, the third lens group G ₃ is moved in a direction substantially perpendicular to the optical axis with the image position displacing unit for image stabilization, the third lens group G ₃ light When the moving amount in the direction substantially orthogonal to the axis is ΔS, the focal length of the third lens unit is f ₃ , the focal length of the fourth lens unit is f ₄ , and the moving amount of the image during zooming is ΔY, _{△ Y = f 4 / f 3} · △ having a vibration reduction function that satisfies the relationship of S's - zoom lens. 2. The focal length at the wide-angle end of the zoom lens is f
_Assuming that _{W is} the focal length at the telephoto end, f _T , and the maximum displacement of the third lens group G ₃ during vibration isolation is ΔS _max , then 0.5 <f ₃ / (f _W · f _T ) ^1/2 The zoom lens having an image stabilizing function according to claim 1, wherein <1 ΔS _max / f ₃ <0.1 is satisfied. 3. A flare stop that blocks unnecessary light when the third lens group G ₃ is moved in a direction substantially orthogonal to the optical axis for image stabilization is arranged in a state fixed to the optical axis. A zoom lens having a vibration-proof function according to claim 1 or 2, which is provided.