JP2001337272A - Zoom lens with camera shake correction function and video camera using the same - Google Patents

Abstract

(57) Abstract: In a five-group zoom lens, a two-lens third lens group fixed to an image plane at the time of zooming and focusing is moved perpendicularly to the optical axis. To compensate for camera shake. SOLUTION: The effective diameter of the first lens from the object side of the first lens group 21 is C1, the effective diameter of the second lens from the object side of the first lens group 21 is C2, and the first lens group 21.
Assuming that the effective diameter of the third lens from the object side is C3, the following conditional expressions (Equation 71) and (Equation 72) are satisfied. [Equation 71] 0.80 <C2 / C1 <1.00 [Equation 72] 0.65 <C3 / C1 <1.00

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens equipped with a camera shake correction function which is used in a video camera or the like and has a camera shake correction function for optically correcting image shake caused by camera shake, vibration, or the like.

[0002]

2. Description of the Related Art Conventionally, in a photographing system such as a video camera, a shake preventing function for preventing vibration such as camera shake has been essential, and various types of anti-shake optical systems have been proposed.

For example, in Japanese Patent Application Laid-Open No. Hei 8-29737, a two-lens optical system for camera shake correction is mounted on the front surface of a zoom lens, and one of them is moved perpendicularly to the optical axis. Thus, the movement of the image due to camera shake is corrected.

Further, Japanese Patent Application Laid-Open No. 7-128619 discloses a four-group zoom lens, in which a part of a third lens group constituted by a plurality of lenses is vertically arranged with respect to an optical axis. By moving, the movement of the image due to camera shake is corrected.

[0005]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No. Hei 8-2
In the camera disclosed in Japanese Patent No. 9737, since the optical system for camera shake correction is mounted on the front surface of the zoom lens, the lens diameter of the optical system for camera shake correction becomes large. In addition, the size of the entire apparatus is accordingly increased, and the load on the drive system is also increased. Therefore, it is disadvantageous for small size, light weight, and power saving.

[0006] In the camera disclosed in Japanese Patent Application Laid-Open No. 7-128619, a part of a third lens group fixed to an image plane is moved perpendicularly to an optical axis to thereby shake an image due to camera shake. This is advantageous in terms of size as compared with a type in which an optical system for camera shake correction is mounted on the front of the zoom lens, but the lens group for camera shake correction is composed of three lenses. Therefore, the burden on the actuator was large.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art, and is a zoom lens having a five-group configuration, the two lenses being fixed to an image plane at the time of zooming and focusing. It is an object of the present invention to provide a zoom lens equipped with a camera shake correction function capable of correcting a camera shake by moving a third lens group having a configuration perpendicular to an optical axis.

[0008]

According to a first aspect of the present invention, there is provided a zoom lens having a positive refractive power which is arranged in order from an object side to an image plane side. A first lens group fixed to the image plane, a second lens group having a negative refractive power and performing a zooming action by moving on the optical axis, and a positive refractive power; A third lens group fixed in the optical axis direction at the time of zooming and focusing, a fourth lens group having a negative refractive power and fixed with respect to the image plane, and having a positive refractive power. A fifth lens group that moves on the optical axis so as to keep the image plane that fluctuates with the movement of the second lens group on the optical axis and the movement of the object at a fixed position from the reference plane. A zoom lens, wherein the first lens group is a lens having a negative refractive power and arranged in order from the object side;
A second lens group including a first lens having a positive refractive power and a second lens having a positive refractive power, wherein the second lens group is a lens having a first negative refractive power, The third lens group includes a lens having a positive refractive power and a meniscus lens having a negative refractive power, which are arranged in order from the object side. The fourth lens group is a lens having a negative refractive power, which is arranged in order from the object side in order to correct the movement of the image due to camera shake. The fifth lens group is a lens having a negative refractive power, a first positive refractive power lens, and a second positive refractive power lens, which are arranged in order from the object side. A first lens from the object side of the first lens group. The effective diameter of the C1, the effective diameter of the from the object side of the first lens group an effective diameter of the second lens C2, the third lens from the object side of the first lens group C
When the number is 3, the first lens group is expressed by the following (Equation 26):
The conditional expression (27) is satisfied. [Equation 26] 0.80 <C2 / C1 <1.00 [Equation 27] 0.65 <C3 / C1 <1.00 Also, the second configuration of the zoom lens according to the present invention is as follows. A first lens unit having a positive refractive power and fixed with respect to the image plane, arranged in order toward the side, and a variable power function having a negative refractive power and moving on the optical axis And a third lens group having a positive refractive power and fixed in the optical axis direction during zooming and focusing, and a negative lens power as a whole, A fourth lens group fixed with respect to an image plane having a positive refracting power, and an image plane which fluctuates in accordance with the movement of the second lens group on the optical axis and the movement of the object at a fixed position from the reference plane. A fifth lens group that moves on the optical axis so as to maintain
The lens group includes a lens having a negative refractive power, a lens having a first positive refractive power, and a lens having a second positive refractive power, which are arranged in order from the object side. A first lens having a negative refractive power, a lens having a second negative refractive power, and a lens having a positive refractive power arranged in order from the side, wherein the third lens group is arranged in order from the object side. In addition, the lens consists of a lens with a positive refractive power and a lens with a negative refractive power whose surface on the image side is flat, and moves in the direction perpendicular to the optical axis in order to correct the movement of the image due to camera shake. It is possible that the fourth lens group is arranged in order from the object side,
The fifth lens group is composed of a cemented lens of a lens having a negative refractive power and a lens having a positive refractive power, and the fifth lens group is a lens having a negative refractive power and a lens having a first positive refractive power arranged in order from the object side. , And a second lens having a positive refractive power, wherein the effective diameter of the first lens from the object side of the first lens group is C1,
When the effective diameter of the second lens from the object side of the first lens group is C2 and the effective diameter of the third lens from the object side of the first lens group is C3, the first lens group is It is characterized by satisfying the conditional expressions (Equation 28) and (Equation 29). [Equation 28] 0.80 <C2 / C1 <1.00 [Equation 29] 0.65 <C3 / C1 <1.00 In the third configuration of the zoom lens according to the present invention, the image plane is arranged from the object side. A first lens unit having a positive refractive power and fixed with respect to the image plane, arranged in order toward the side, and a variable power function having a negative refractive power and moving on the optical axis And a third lens group having a positive refractive power and fixed in the optical axis direction at the time of zooming and focusing, and a second lens group having a negative refractive power and And a fourth lens unit fixed in position, having a positive refractive power, and keeping an image plane, which fluctuates with the movement of the second lens group on the optical axis and the movement of an object, at a fixed position from the reference plane. A fifth lens group that moves on the optical axis as described above, wherein the first lens group is a negative lens arranged in order from the object side. Folding lens,
A second lens group including a first lens having a positive refractive power and a second lens having a positive refractive power, wherein the second lens group is a lens having a first negative refractive power, The third lens group includes a lens having a positive refractive power and a biconcave lens having a negative refractive power, which are arranged in order from the object side. The fourth lens group is a lens having a negative refractive power, which is arranged in order from the object side in order to correct the movement of the image due to camera shake. And a cemented lens of a lens having a positive refractive power,
The lens group includes a lens having a negative refractive power, a lens having a first positive refractive power, and a lens having a second positive refractive power, which are arranged in order from the object side. From C1, the effective diameter of the first lens is C1, the effective diameter of the second lens from the object side of the first lens group is C2, and the effective diameter of the third lens from the object side of the first lens group is C1. When C3 is set, the first lens group is expressed by the following (Equation 30) and (Equation 3).
A zoom lens satisfying the conditional expression (1). [Equation 30] 0.80 <C2 / C1 <1.00 [Equation 31] 0.65 <C3 / C1 <1.00 In the fourth configuration of the zoom lens according to the present invention, the image plane is arranged from the object side. A first lens unit having a positive refractive power and fixed with respect to the image plane, arranged in order toward the side, and a variable power function having a negative refractive power and moving on the optical axis And a third lens group having a positive refractive power and fixed in the optical axis direction at the time of zooming and focusing, and a second lens group having a negative refractive power and And a fourth lens unit fixed in position, having a positive refractive power, and keeping an image plane, which fluctuates with the movement of the second lens group on the optical axis and the movement of an object, at a fixed position from the reference plane. A fifth lens group that moves on the optical axis as described above, wherein the first lens group is a negative lens arranged in order from the object side. Folding lens,
A second lens group including a first lens having a positive refractive power and a second lens having a positive refractive power, wherein the second lens group is a lens having a first negative refractive power, The third lens group includes a lens having a positive refractive power and a lens having a negative refractive power, which are arranged in order from the object side, and includes a lens having a negative refractive power and a lens having a positive refractive power. The whole of the fourth lens group is movable in the direction perpendicular to the optical axis in order to correct the movement of the image due to camera shake, and the fourth lens group is arranged in order from the object side and has a separated negative refractive power. The fifth lens group is composed of a lens having a negative refractive power and a lens having a negative refractive power.
A lens having a first positive refractive power and a second positive refractive power, wherein the effective diameter of the first lens from the object side of the first lens group is C1, the object of the first lens group When the effective diameter of the second lens from the side is C2, and the effective diameter of the third lens from the object side of the first lens group is C3, the first lens group has the following (Equation 32), (Equation 32) 33. A zoom lens characterized by satisfying the conditional expression (33). [Equation 32] 0.80 <C2 / C1 <1.00 [Equation 33] 0.65 <C3 / C1 <1.00 By satisfying the above-mentioned conditional expression, a sufficient peripheral light amount can be secured, and therefore, camera shake correction is performed. It is possible to make the change in the peripheral light amount that sometimes occurs inconspicuous. If the upper limit of the above conditional expression is exceeded, the diameter of the second lens and the third lens is larger than the diameter of the first lens, so that the lens barrel becomes large, and furthermore, harmful light such as flare. Also increase.
On the other hand, when the value goes below the lower limit of the conditional expression, a sufficient amount of light cannot be secured, so that a change in the amount of light at the time of camera shake correction becomes conspicuous. Further, since the amount of light is ensured by the first lens group which is always fixed, even if the lens diameter is increased, the load on the actuator is increased as in the case where the amount of light is secured by the fifth lens group which is a movable lens group. There is no such thing.

When the lens having a negative refractive power in the third lens group is a meniscus lens, the angles of rays incident on the object-side surface and the image-side surface of the lens are close to each other.
This is advantageous for obtaining good aberration.

When the surface of the third lens unit having a negative refractive power on the image plane side is flat, there is an advantage that processing is easy.

When the negative lens of the third lens group is a biconcave lens, the power is not borne by one of the surfaces, so that the bias of each lens in the lens group is reduced. The core tolerance can be reduced.

Further, since the fourth lens group is composed of separated lenses, the degree of freedom in designing is increased, so that the aberration can be corrected well.

Further, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, it is preferable that at least one surface of the lens constituting the second lens group is aspheric. According to this preferred example, it is possible to satisfactorily correct coma occurring at the periphery of the screen.

Also, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, it is preferable that at least one surface of the lens constituting the third lens group is an aspheric surface. According to this preferred example, it is possible to satisfactorily correct the spherical aberration and the aberration generated at the time of camera shake correction.

Further, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, on the i-th aspheric surface of the second lens group, the local radius of curvature at 10% of the lens effective diameter is r _2i1 , and the local radius of curvature at 90% of the lens effective diameter is local. When the radius of curvature is r _2i9 ,
Is preferably satisfied. [ _Equation 34] 0.70 <r _2i1 / r _2i9 <1.60 The conditional expression (Equation 34) is a conditional expression for defining the aspherical amount, and is a sufficient aberration for realizing high resolution. This is a conditional expression for obtaining performance. If the upper limit of the conditional expression is exceeded, the correction amount of coma in the peripheral portion of the screen becomes too small. On the other hand, when the value goes below the lower limit of this conditional expression, the amount of correction of coma becomes too large, and it becomes impossible to obtain sufficient aberration performance.

Further, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, on the i-th aspheric surface of the third lens group, the local radius of curvature at 10% of the lens effective diameter is r _3i1 , and the local radius of curvature at 90% of the lens effective diameter is local. When the radius of curvature is r _3i9 , the following ( _Equation 35)
Is preferably satisfied. [ _Expression 35] 0.05 <r _3i1 / r _3i9 <2.00 The conditional expression (Expression 35) is a conditional expression for defining the amount of aspherical surface, and is a sufficient aberration for realizing high resolution. This is a conditional expression for obtaining performance. When the value exceeds the upper limit of the conditional expression, the correction amount of the spherical aberration becomes too small. Also, coma flare is likely to occur when the lens moves. On the other hand, when the value goes below the lower limit of the conditional expression, the correction amount of the spherical aberration becomes too large, and it becomes impossible to obtain sufficient aberration performance.

Incidentally, the local radius of curvature C mentioned here is:
Based on the aspheric coefficient calculated from the sag amount of the surface shape,
It is a value obtained by algebraically calculated, and can be obtained by the equations (a) and (b) shown in the following (Equation 36).

[0018]

[Equation 36]

Further, the zoom lenses according to the first to the first aspects of the present invention.
In the fourth configuration, it is preferable that the sag amount on the object-side surface and the image-side surface of the lens having a positive refractive power of the third lens unit is equal.

Further, the zoom lenses according to the first to fifth aspects of the present invention are described below.
In the fourth configuration, when the focal length of the third lens group is f ₃ , and the combined focal length of the third lens group and the fourth lens group is f ₃₄ , 3
It is preferable to satisfy the conditional expression (7). [Equation 37] 0.30 <| f ₃ / f ₃₄ | <0.95 The conditional expression (Equation 37) is a conditional expression for defining the focal length of the camera shake correction lens (third lens group). It is. When the value goes below the lower limit of the conditional expression, the power of the camera shake correction lens (third lens group) becomes too strong, and the deterioration of aberration performance becomes large. In addition, the assembly tolerance during manufacturing becomes strict. On the other hand, if the upper limit of this conditional expression is exceeded,
Since the amount of movement of the lens at the time of camera shake correction increases, the lens diameter also increases, which is disadvantageous for miniaturization.

Also, the zoom lens according to the present invention has the following first to first aspects.
In the fourth configuration, when the focal length of the entire system at the wide-angle end is fw, and the distance from the last lens surface to the imaging surface in air is BF, the following conditional expression (38) is satisfied. preferable. [Equation 38] 2.0 <BF / fw <5.0 The conditional expression (Equation 38) is a conditional expression for realizing a zoom lens having a long back focus such as three plates. If the lower limit of the conditional expression is not reached, a color separation optical system having a length sufficient for sufficient color separation cannot be inserted. On the other hand, when the value exceeds the upper limit of the conditional expression, the back focus becomes unnecessarily long, and it is difficult to reduce the size.

Further, the first to the first zoom lenses of the present invention.
In the fourth configuration, the focal length of the entire system at the wide-angle end is fw, the focal length of the i-th lens group is f _i (i = 1 to 5),
The combined focal length of the third lens group and the fourth lens group is
When f is ₃₄ , it is preferable to satisfy the following conditional expressions (Expression 39) to (Expression 42). [Expression 39] 5.0 <f ₁ /fw<8.0 [number _{40] 0.5 <| f 2 |} / fw <1.6 [ number 41] 7.0 <f ₃₄ /fw<13.5 [Equation 42] 2.0 <f ₅ /fw<5.0 The conditional expression (Equation 39) above is a conditional expression relating to the refractive power of the first lens group. If the lower limit of the conditional expression is not reached, the first
Since the refractive power of the lens group becomes too large, it becomes difficult to correct spherical aberration on the long focal length side. On the other hand, when the value exceeds the upper limit of the conditional expression, the lens length increases, and a compact zoom lens cannot be realized.

The conditional expression (40) is a conditional expression relating to the refractive power of the second lens unit. When the value goes below the lower limit of this conditional expression, the size can be reduced, but the Petzval sum of the entire system becomes negative and the field curvature cannot be corrected. On the other hand, when the value exceeds the upper limit of the conditional expression, it is easy to correct the aberration, but the length of the variable power system becomes longer, and it becomes difficult to make the entire system compact.

The conditional expression (41) is a conditional expression relating to the refractive power of the third lens unit. When the value goes below the lower limit of this conditional expression, the refractive power of the third lens group becomes too large, so that it becomes difficult to correct spherical aberration. On the other hand, when the value exceeds the upper limit of the conditional expression, the combined system of the first to third lens units becomes a divergent system, so that the lens outer diameter of the fourth lens unit located behind the lens system can be reduced. In addition, the Petzval sum of the whole system cannot be reduced.

The conditional expression (Expression 42) is a conditional expression relating to the refractive power of the fourth lens unit. If the lower limit of the conditional expression is not reached, the screen coverage range becomes narrow, and it is necessary to increase the lens diameter of the first lens group in order to obtain a desired range, so that a reduction in size and weight cannot be realized. On the other hand, when the value exceeds the upper limit of this conditional expression, it is easy to correct aberrations, but the amount of movement of the fourth lens unit at the time of short-distance photographing becomes large, and not only is it difficult to make the entire system compact, but also It becomes difficult to correct the imbalance of off-axis aberrations at the time of distance shooting and at the time of long distance shooting.

Further, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, the Abbe number of one lens of the third lens group is ν ₃₁ , the Abbe number of the other lens of the third lens group is ν ₃₂ , and the Abbe number of one lens of the fourth lens group is Assuming that the number is ν ₄₁ and the Abbe number of the other lens in the fourth lens group is ν ₄₂ , the following (Equation 43) and (Equation 44)
Is preferably satisfied. [Equation 43] | ν ₃₁ −ν ₃₂ |> 25 [Equation 44] | ν ₄₁ −ν ₄₂ |> 25 The above-mentioned conditional expressions (Equation 43) and (Equation 44) reduce deterioration of chromatic aberration of magnification during camera shake correction. This is an equation for reducing the size. At the time of camera shake correction, lateral chromatic aberration occurs because the lens is shifted. Abbe number difference of each lens group is calculated as above (Equation 4).
By setting as in (3) and (Equation 44), a sufficient achromatism effect can be provided, so that deterioration of chromatic aberration of magnification can be reduced even during lens shift.

Further, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, the refractive index of a lens having a positive refractive power of the third lens group is nd ₃₁ , the refractive index of a lens having a negative refractive power of the third lens group is nd ₃₂ , and the fourth lens group is When the refractive index of the lens having a negative refractive power is nd ₄₁ and the refractive index of the lens having a positive refractive power of the fourth lens group is nd ₄₂ , the following conditional expressions (Expression 45) to (Expression 48) are obtained. It is preferable to satisfy. [Expression 45] nd ₃₁ <1.60 [Expression 46] nd ₄₁ > 1.50 [Expression 47] | nd ₃₁ −nd ₃₂ |> 0.25 [Expression 48] | nd ₄₁ −nd ₄₂ |> 0.20 The conditional expressions (Equation 45) to (Equation 48) are conditional expressions for correcting curvature of field while suppressing deterioration of chromatic aberration of magnification during camera shake correction. If the upper limit of the conditional expression (45) is exceeded, the radius of curvature of the surface of the convex lens (a lens having a positive refractive power) becomes large. If the lower limit of the conditional expression (46) is exceeded, a concave lens is obtained. Since the radius of curvature of the surface of the (negative refractive power lens) decreases, the negative curvature of field increases. If the lower limits of the conditional expressions (Equation 47) and (Equation 48) are not satisfied, chromatic aberration cannot be sufficiently corrected, and chromatic aberration occurs during lens shift.

Further, the first to the first zoom lenses of the present invention.
In a fourth configuration, on the object side of the third lens group,
A fixed stop is provided for the image plane, and the stop diameter of the stop decreases with an increase in the focal length of the entire system. When the stop diameter at the telephoto end is St and the stop diameter at the wide-angle end is Sw, It is preferable to satisfy the conditional expression (49). [Equation 49] St / Sw <0.92 According to this preferred example, deterioration of aberration at the long focal length side, particularly at the telephoto end, can be reduced.

Further, the first to the fifth zoom lenses of the present invention.
In the fourth configuration, it is preferable that the second lens from the object side of the first lens group is blackened or a light-shielding sheet is attached to cut light rays passing through the outer peripheral portion of the lens. When the diameters of the second lens and the third lens from the object side of the first lens group are large, if light rays at the peripheral portion of the screen are cut by the lens barrel, the outer peripheral portion of the barrel becomes large, making it difficult to reduce the size. Becomes The lens barrel can be reduced in size by determining the effective diameter of the lens using a blackened or light-shielding sheet.

Further, the first to the first zoom lenses of the present invention.
In the fourth configuration, when the rate of movement of the image on the screen during camera shake correction changes from wide angle to telephoto, it is preferable that the ratio increases in proportion to the zoom ratio. As the angle of view increases, even if camera shake occurs, it becomes less noticeable. By changing the rate of movement of the image in proportion to the zoom ratio, natural camera shake correction can be realized at all zoom positions, and no unnecessary load is imposed on the actuator.

Further, the first to the first zoom lenses of the present invention.
In the fourth configuration, the maximum movement amount of the third lens unit at the focal length f of the entire system at the time of camera shake correction is Y, the movement amount of the third lens unit at the telephoto end is Yt, and the focal length at the telephoto end is Yt. ft, the following (Equation 50), (Equation 51)
Is preferably satisfied. [Equation 50] Yt> Y [Equation 51] (Y / Yt) / (f / ft) <1.5 The above-mentioned conditional expressions (Equation 50) and (Equation 51) are conditions relating to the amount of movement of the third lens group. It is an expression. When the correction angle is constant in the entire zoom range, the larger the zoom ratio, the larger the amount of movement of the third lens group, and conversely, the smaller the zoom ratio, the smaller the amount of movement of the third lens group. In the vicinity of the telephoto end, since the angle of view is narrow, if the upper limit of the conditional expression (Equation 50) is exceeded, the performance will be degraded and the image will become unnatural.

The conditional expression (Equation 51) defines the upper limit of the camera shake on the wide-angle side. If the upper limit is exceeded, the correction becomes excessive and the deterioration of the optical performance becomes large. In addition, the screen after correction becomes unnatural.

Further, by constituting a video camera using a zoom lens having any one of the above configurations, it is possible to realize a compact and high-performance video camera with a camera shake correction function.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to embodiments.

FIG. 1 is a basic configuration diagram of a zoom lens equipped with a camera shake correction function according to the present invention.

As shown in FIG. 1, first from the object side (the left side in FIG. 1) to the image plane side (the right side in FIG. 1),
A lens group, a second lens group, a third lens group, a fourth lens group, and a fifth lens group are arranged, thereby forming a zoom lens.

The first lens group includes a lens having a negative refractive power, a lens having a first positive refractive power, arranged in order from the object side,
And a lens having a second positive refractive power, has a positive refractive power as a whole, and is fixed to the image plane.

The second lens group includes a first lens having a negative refractive power, a lens having a second negative refractive power, and a lens having a positive refractive power, which are arranged in order from the object side. It has a refracting power and performs a zooming effect by moving on the optical axis.

The third lens group includes, in order from the object side, a lens having a positive refractive power and a lens having a negative refractive power.
It has a positive refractive power as a whole and is fixed in the optical axis direction at the time of zooming and at the time of focusing. Further, the entire third lens group is movable in a direction perpendicular to the optical axis in order to correct movement of an image due to camera shake. When the rate of movement of the image on the screen at the time of camera shake correction changes from wide angle to telephoto, it is desirable that it increases in proportion to the zoom ratio. As the angle of view increases, even if camera shake occurs, it becomes less noticeable. By changing the rate of movement of the image in proportion to the zoom ratio, natural camera shake correction can be realized at all zoom positions, and no unnecessary load is imposed on the actuator.

The fourth lens group includes a lens having a negative refractive power and a lens having a positive refractive power, which are arranged in order from the object side, has a negative refractive power as a whole, and is fixed with respect to the image plane. It is in the state that was done.

The fifth lens group includes, in order from the object side, a lens having a negative refractive power, a lens having a first positive refractive power,
And a lens having a second positive refractive power, having a positive refractive power as a whole, and moving an image plane, which varies with the movement of the second lens group on the optical axis and the movement of the object, from the reference plane. Move on the optical axis to keep it at a fixed position.

[First Embodiment] In the present embodiment, the lens having a negative refractive power that constitutes the third lens group is a meniscus lens. Further, a lens having a negative refractive power and a lens having a positive refractive power which constitute the fourth lens group are cemented. Further, at least one surface of the second lens group and the third lens group is aspheric.

(Example 1) The following (Table 1) shows specific numerical examples of the zoom lens in this example.

[0044]

[Table 1]

In the above (Table 1), r is the radius of curvature of the lens surface, d is the thickness of the lens or the air gap between the lenses, n
Represents the refractive index of each lens with respect to the d-line, and ν represents the Abbe number of each lens with respect to the d-line.

The following Table 2 shows the aspherical coefficients of the zoom lens of this embodiment.

[0047]

[Table 2]

The following Table 3 shows the variable air gap (mm) obtained by zooming when the object point is at a position 2 m from the front end of the lens.

[0049]

[Table 3]

The standard position in the above (Table 3) is a position where the magnification of the second lens group is -1. In Table 3 above, f (mm), F / No, and ω (degree) are the focal length, F number, and incidence at the wide angle end, the standard position, and the telephoto end of the zoom lens of Table 1 above, respectively. The angle of view is half.

FIG. 2 shows a configuration of a zoom lens based on the above data (Table 1), and FIGS. 3 to 5 show aberration performance diagrams of the present zoom lens at the wide-angle end, the standard position, and the telephoto end. 3 to 5, (a), (b),
(C), (d) and (e) are spherical aberration (mm), respectively.
It shows astigmatism aberration (mm), distortion (%), axial chromatic aberration (mm), and chromatic aberration of magnification (mm). Further, in the figures of the spherical aberration in each figure (a), the solid line shows the value for the d-line. Further, in the astigmatism diagrams of each diagram (b), the solid line indicates sagittal field curvature, and the broken line indicates meridional field curvature. In addition, in the axial chromatic aberration in each diagram (d), the solid line shows the value for the d line, the short broken line shows the value for the F line, and the long broken line shows the value for the C line. Also,
In each of the diagrams of the chromatic aberration of magnification in FIG.
The line and the long dashed line indicate values for the C line, respectively.

As shown in FIG. 2, the zoom lens according to the present embodiment has a first lens group 21, a second lens group 22, and a third lens group 2 arranged in order from the object side to the image plane side.
3, a fourth lens group 24, and a fifth lens group 25. A variable stop is arranged on the optical axis between the second lens group 22 and the third lens group 23. The first lens group 21 has a positive refractive power as a whole, and is fixed with respect to the image plane during zooming and focusing. The second lens group 22 has a negative refractive power as a whole, and performs a zooming action by moving on the optical axis. Third lens group 2
Numeral 3 is composed of a lens having a positive refractive power and a lens having a negative refractive power, has a positive refractive power as a whole, and is fixed in the optical axis direction at the time of zooming and focusing. . 4th
The lens group 24 includes a lens having a negative refractive power and a lens having a positive refractive power, and has a negative refractive power as a whole,
It is fixed to the image plane during zooming and during focusing. The fifth lens group 25 has a positive refractive power as a whole, and moves on the optical axis to simultaneously move an image by zooming and adjust focus. In addition, when camera shake occurs, image shake is corrected by moving the third lens group 23 in a direction perpendicular to the optical axis.

The lenses having a positive refractive power of the third lens group 23 have the same sag amount on the object side surface and the image side surface.

The effective diameter of the first lens from the object side of the first lens group 21 is C1, the effective diameter of the second lens from the object side of the first lens group 21 is C2, and the object of the first lens group 21 is C2. When the effective diameter of the third lens from the side is C3, the first lens group 21 satisfies the following conditional expressions (Expression 52) and (Expression 53). [Equation 52] 0.80 <C2 / C1 <1.00 [Equation 53] 0.65 <C3 / C1 <1.00 Also, in the i-th aspherical surface of the second lens group 22, the lens effective diameter is 1 Let r be the local radius of curvature at a given radius
_2i1 , When the local radius of curvature at 90% of the effective lens diameter is r _2i9 , it is desirable that the following conditional expression (Equation 54) is satisfied. [ _Equation 54] 0.70 <r _2i1 / r _2i9 <1.60 In the i-th aspherical surface of the third lens unit 23, the local radius of curvature at 10% of the effective lens diameter is represented by r.
_3i1 , When the local radius of curvature at 90% of the effective lens diameter is r _3i9 , it is desirable to satisfy the following expression (55). [ _Equation 55] 0.05 <r _3i1 / r _3i9 <2.00 Further, the focal length of the correction lens group (third lens group 23) is f ₃ , and the combined focal point of the third lens group 23 and the fourth lens group 24 is When the distance is f ₃₄ , the third lens group is expressed by the following (Equation 56)
It is desirable to satisfy the following conditional expression. [Equation 56] 0.30 <| f ₃ / f ₃₄ | <0.95 Also, when the focal length of the entire system at the wide-angle end is fw, and the distance from the last lens surface to the imaging surface in air is BF. , It is desirable to satisfy the following conditional expression (Equation 57). [Equation 57] 2.0 <BF / fw <5.0 The focal length of the entire system at the wide-angle end is fw, the focal length of the ith lens group is f _i (i = 1 to 5), and the third lens group is 23
When When the composite focal length of the fourth lens group 24 and a f _34,
It is desirable to satisfy the following conditional expressions (Equation 58) to (Equation 61). [Equation 58] 5.0 <f ₁ /fw<8.0 [Equation 59] 0.5 <| f ₂ | / fw <1.6 [Equation 60] 7.0 <f ₃₄ /fw<13.5 [Equation 61] 2.0 <f ₅ /fw<5.0 The Abbe number of one lens of the third lens group 23 is represented by ν.
₃₁ , the Abbe number of the other lens of the third lens group 23 is ν ₃₂ , and the Abbe number of one lens of the fourth lens group 24 is ν
_41, an Abbe number of the other lens in the fourth lens group 24 [nu ₄₂
In this case, it is preferable to satisfy the following conditional expressions (Equation 62) and (Equation 63). [Equation 62] | ν ₃₁ −ν ₃₂ |> 25 [Equation 63] | ν ₄₁ −ν ₄₂ |> 25 Further, the refractive index of the convex lens (lens having a positive refractive power) of the third lens group 23 is nd ₃₁ , The refractive index of the concave lens (lens having a negative refractive power) of the third lens group 23 is nd ₃₂ , and the refractive index of the concave lens (lens having a negative refractive power) of the fourth lens group 24 is n.
d ₄₁ , when the refractive index of the convex lens (lens having a positive refractive power) of the fourth lens group 24 is nd ₄₂ ,
It is desirable to satisfy the conditional expression (Equation 67). [Expression 64] nd ₃₁ <1.60 [Expression 65] nd ₄₁ > 1.50 [Expression 66] | nd ₃₁ −nd ₃₂ |> 0.25 [Expression 67] | nd ₄₁ −nd ₄₂ |> 0.20 Also, the stop diameter of the fixed stop with respect to the image plane provided on the object side of the third lens group 23 decreases as the focal length of the entire system increases, the stop diameter at the telephoto end is St, and the stop diameter at the wide-angle end is St. Is Sw, it is desirable to satisfy the following conditional expression (Equation 68). [Equation 68] St / Sw <0.92 Also, the maximum movement amount of the third lens group 23 at the focal length f of the entire system at the time of camera shake correction is Y, the movement amount of the third lens group 23 at the telephoto end is Yt, When the focal length at the telephoto end is ft, it is desirable to satisfy the following conditional expressions (Equation 69) and (Equation 70). [Equation 69] Yt> Y [Equation 70] (Y / Yt) / (f / ft) <1.5 Hereinafter, the above (Equation 5) in the zoom lens of the present embodiment will be described.
The values of the conditional expressions 2) to (Equation 70) are shown.

C1 = 17.80 mm, C2 = 17.26
mm, C3 = 15.84 mm C2 / C1 = 0.97 C3 / C1 = 0.89 r ₂₁₁ / r ₂₁₉ = 0.97 r ₃₁₁ / r ₃₁₉ = 0.58 | f ₃ / f ₃₄ | = 0.61 _{BF / fw = 3.70 f 1 /fw=7.12} | f 2 | /fw=1.45 f 34 /fw=10.15 f 5 /fw=3.38 | ν 31 -ν 32 | = 37 0.7 | ν ₄₁ −ν ₄₂ | = 36.8 nd ₃₁ = 1.51450 nd ₄₁ = 1.60311 | nd ₃₁ −nd ₃₂ | = 0.29 | nd ₄₁ −nd ₄₂ | = 0.24 St / Sw = 0.58 Yt = 0.30 Wide-angle end Y = 0.04 (Y / Yt) / (f / ft) = 1.33 Standard position Y = 0.12 (Y / Yt) / (f / ft) = 0.92 As is clear from the aberration performance diagrams shown in FIGS. 3 to 5, the zoom lens according to the present embodiment has a sufficient aberration to realize high resolution. It has a positive ability.

FIG. 6 shows an aberration performance chart at the time of correcting a camera shake of 0.35 ° at the telephoto end. In FIG. 6,
(F), (g), and (h) are relative image heights of 0.75,
The lateral aberration is shown at the center of the screen and at a relative image height of -0.75. The solid line is the d line, the short broken line is the F line, and the long broken line is the C line.
The values for the lines are shown.

As is clear from FIG. 6, the zoom lens of this embodiment has good aberration performance even at the time of camera shake correction.

(Example 2) The following (Table 4) shows specific numerical examples of the zoom lens in this example.

[0059]

[Table 4]

In Table 4 above, r is the radius of curvature of the lens surface, d is the thickness of the lens or the air gap between the lenses, n
Represents the refractive index of each lens with respect to the d-line, and ν represents the Abbe number of each lens with respect to the d-line.

Table 5 below shows the aspherical surface coefficients of the zoom lens of this embodiment.

[0062]

[Table 5]

Table 6 below shows the values of the variable air gap (mm) obtained by zooming when the object point is at a position 2 m from the front end of the lens.

[0064]

[Table 6]

The standard position in the above (Table 6) is a position where the magnification of the second lens group is -1. In Table 6 above, f (mm), F / No, and ω (degree) are the focal length, F number, and incidence at the wide-angle end, the standard position, and the telephoto end of the zoom lens in Table 4 above, respectively. The angle of view is half.

FIGS. 7 to 9 show aberration performance charts of the zoom lens at the wide-angle end, the standard position, and the telephoto end based on the above data (Table 4). 7 to 9,
(A), (b), (c), (d), and (e) are spherical aberration (mm), astigmatism aberration (mm), distortion (%), axial chromatic aberration (mm), and chromatic aberration of magnification, respectively. (Mm). Further, in the diagram of the spherical aberration in each diagram (a),
The solid line shows the value for the d line. Each figure (b)
In the diagram of astigmatism, the solid line indicates sagittal field curvature and the broken line indicates meridional field curvature. Further, in the axial chromatic aberration of each figure (d), the solid line is the d line,
The short broken line shows the value for the F line, and the long broken line shows the value for the C line. Further, in the graph of the chromatic aberration of magnification in each figure (e), a short broken line indicates a value for the F line, and a long broken line indicates a value for the C line.

The values of the conditional expressions (Equation 52) to (Equation 70) for the zoom lens of this embodiment are shown below.

C1 = 17.80 mm, C2 = 17.26
mm, C3 = 15.84 mm C2 / C1 = 0.97 C3 / C1 = 0.89 r ₂₁₁ / r ₂₁₉ = 1.07 r ₃₁₁ / r ₃₁₉ = 0.13 | f ₃ / f ₃₄ | = 0.87 _{BF / fw = 3.69 f 1 /fw=7.13} | f 2 | /fw=1.45 f 34 /fw=7.04 f 5 /fw=3.66 | ν 31 -ν 32 | = 71 _{.1 | ν 41 -ν 42 | =} 42.9 nd 31 = 1.43425 nd 41 = 1.59240 | nd 31 -nd 32 | = 0.41 | nd 41 -nd 42 | = 0.21 St / Sw = 0.58 Yt = 0.30 Wide-angle end Y = 0.04 (Y / Yt) / (f / ft) = 1.33 Standard position Y = 0.12 (Y / Yt) / (f / ft) = 0.92 As is clear from the aberration performance diagrams shown in FIGS. 7 to 9, the zoom lens according to the present embodiment has a sufficient aberration compensation to realize high resolution. It has the ability.

FIG. 10 shows an aberration performance chart at the time of correcting a camera shake of 0.36 ° at the telephoto end. In FIG. 10,
(F), (g), and (h) are relative image heights of 0.75,
The lateral aberration is shown at the center of the screen and at a relative image height of -0.75. The solid line is the d line, the short broken line is the F line, and the long broken line is the C line.
The values for the lines are shown.

As is apparent from FIG. 10, the zoom lens of this embodiment has good aberration performance even at the time of camera shake correction.

[Second Embodiment] In the present embodiment, the lens having a negative refractive power constituting the third lens group has a flat surface on the image plane side. Further, a lens having a negative refractive power and a lens having a positive refractive power which constitute the fourth lens group are cemented. Further, at least one surface of the second lens group and the third lens group is aspheric.

(Embodiment 3) The following (Table 7) shows specific numerical examples of the zoom lens in this embodiment.

[0073]

[Table 7]

In the above (Table 7), r is the radius of curvature of the lens surface, d is the thickness of the lens or the air gap between the lenses, n
Represents the refractive index of each lens with respect to the d-line, and ν represents the Abbe number of each lens with respect to the d-line.

Table 8 below shows the aspherical surface coefficients of the zoom lens of this embodiment.

[0076]

[Table 8]

The following Table 9 shows the values of the air gap (mm) variable by zooming when the object point is at a position 2 m from the front end of the lens.

[0078]

[Table 9]

The standard position in the above (Table 9) is a position where the magnification of the second lens unit is -1. In Table 9 above, f (mm), F / No, and ω (degree) are the focal length, F number, and incidence at the wide angle end, the standard position, and the telephoto end of the zoom lens of Table 7 above, respectively. The angle of view is half.

FIG. 11 shows a configuration of a zoom lens based on the above data (Table 7), and FIGS. 12 to 14 show aberration performance diagrams of the present zoom lens at the wide angle end, the standard position, and the telephoto end. 12 to 14, (a),
(B), (c), (d), and (e) represent spherical aberration (mm), astigmatism aberration (mm), distortion (%), axial chromatic aberration (mm), and lateral chromatic aberration (mm), respectively. Is shown.
Further, in the figures of the spherical aberration in each figure (a), the solid line shows the value for the d-line. Further, in the astigmatism diagrams of each diagram (b), the solid line indicates sagittal field curvature, and the broken line indicates meridional field curvature. In addition, in the axial chromatic aberration in each diagram (d), the solid line shows the value for the d line, the short broken line shows the value for the F line, and the long broken line shows the value for the C line. Further, in the graph of the chromatic aberration of magnification in each figure (e), a short broken line indicates a value for the F line, and a long broken line indicates a value for the C line.

As shown in FIG. 11, the zoom lens of this embodiment is arranged in order from the object side to the image plane side.
It includes a first lens group 111, a second lens group 112, a third lens group 113, a fourth lens group 114, and a fifth lens group 115. A variable stop is arranged on the optical axis between the second lens group 112 and the third lens group 113.
The first lens group 111 has a positive refractive power as a whole,
It is fixed to the image plane during zooming and during focusing. The second lens group 112 has a negative refractive power as a whole, and performs a zooming action by moving on the optical axis. The third lens group 113 includes a lens having a positive refractive power and a lens having a negative refractive power, has a positive refractive power as a whole, and is fixed in the optical axis direction during zooming and focusing. It is in the state where it was. The fourth lens group 114 is composed of a lens having a negative refractive power and a lens having a positive refractive power, has a negative refractive power as a whole, and is fixed to an image plane during zooming and focusing. It is in the state where it was. Fifth lens group 115
Has a positive refracting power as a whole, and moves on the optical axis to simultaneously move an image by zooming and adjust focus. In addition, when camera shake occurs, image shake is corrected by moving the third lens group 113 in a direction perpendicular to the optical axis.

Further, by introducing an aspherical surface to at least one surface of the lenses constituting the third lens group 113, it is possible to improve the performance when the lens is shifted.

Further, the lenses of the third lens group 113 having a positive refractive power have the same sag amount on the object side surface and the image side surface.

The values of the conditional expressions (Equation 52) to (Equation 70) for the zoom lens of this embodiment are shown below.

C1 = 17.08 mm, C2 = 15.72
mm, C3 = 13.34 mm C2 / C1 = 0.92 C3 / C1 = 0.78 r ₂₁₁ / r ₂₁₉ = 1.41 r ₃₁₁ / r ₃₁₉ = 0.83 r ₃₂₁ / r ₃₂₉ = 0.82 | f _{3 / f 34 | = 0.44 BF} / fw = 3.78 f 1 /fw=7.50 | f 2 | /fw=1.40 f 34 /fw=12.77 f 5 /fw=3.06 | Ν ₃₁ −ν ₃₂ | = 37.7 | ν ₄₁ −ν ₄₂ | = 36.8 nd ₃₁ = 1.51450 nd ₄₁ = 1.60311 | nd ₃₁ −nd ₃₂ | = 0.29 | nd ₄₁ −nd ₄₂ | = 0.24 St / Sw = 0.58 Yt = 0.23 Wide-angle end Y = 0.02 (Y / Yt) / (f / ft) = 0.99 Standard position Y = 0.10 (Y / Yt) / (f / ft) = 0.95 As is clear from the aberration performance diagrams shown in FIGS.
The zoom lens according to the present embodiment has sufficient aberration correction capability to realize high resolution.

FIG. 15 shows an aberration performance diagram at the time of correcting a camera shake of 0.24 ° at the telephoto end. In FIG. 15,
(F), (g), and (h) are relative image heights of 0.75,
The lateral aberration is shown at the center of the screen and at a relative image height of -0.75. The solid line is the d line, the short broken line is the F line, and the long broken line is the C line.
The values for the lines are shown.

As is apparent from FIG. 15, the zoom lens of this embodiment has good aberration performance even at the time of camera shake correction.

[Third Embodiment] In the present embodiment, the lens having a negative refractive power and constituting the third lens group is a biconcave lens. Further, a lens having a negative refractive power and a lens having a positive refractive power which constitute the fourth lens group are cemented. Further, at least one surface of the second lens group and the third lens group is aspheric.

(Embodiment 4) The following (Table 10) shows specific numerical examples of the zoom lens in this embodiment.

[0090]

[Table 10]

In the above (Table 10), r is the radius of curvature of the lens surface, d is the thickness of the lens or the air gap between the lenses,
n is the refractive index of each lens with respect to the d line, and ν is the d of each lens.
Shows the Abbe number for the line.

Table 11 below shows the aspherical surface coefficients of the zoom lens of this embodiment.

[0093]

[Table 11]

The following Table 12 shows the value of the variable air gap (mm) obtained by zooming when the object point is at a position 2 m from the front end of the lens.

[0095]

[Table 12]

The standard position in the above (Table 12) is the second position.
This is the position where the magnification of the lens group becomes -1. In Table 12 above, f (mm), F / No, and ω (degree) are the focal length, F number, and incidence at the wide-angle end, the standard position, and the telephoto end of the zoom lens in Table 10 above, respectively. The angle of view is half.

FIG. 16 shows a configuration of a zoom lens based on the above data (Table 10), and FIGS. 17 to 19 show aberration performance diagrams of the present zoom lens at the wide angle end, the standard position, and the telephoto end. 17 to 19,
(A), (b), (c), (d), and (e) are spherical aberration (mm), astigmatism aberration (mm), distortion (%), axial chromatic aberration (mm), and chromatic aberration of magnification, respectively. (Mm). Further, in the diagram of the spherical aberration in each diagram (a),
The solid line shows the value for the d line. Each figure (b)
In the diagram of astigmatism, the solid line indicates sagittal field curvature and the broken line indicates meridional field curvature. Further, in the axial chromatic aberration of each figure (d), the solid line is the d line,
The short broken line shows the value for the F line, and the long broken line shows the value for the C line. Further, in the graph of the chromatic aberration of magnification in each figure (e), a short broken line indicates a value for the F line, and a long broken line indicates a value for the C line.

As shown in FIG. 16, the zoom lens of this embodiment is arranged in order from the object side to the image plane side.
It includes a first lens group 161, a second lens group 162, a third lens group 163, a fourth lens group 164, and a fifth lens group 165. A variable stop is arranged on the optical axis between the second lens group 162 and the third lens group 163.
The first lens group 161 has a positive refractive power as a whole,
It is fixed to the image plane during zooming and during focusing. The second lens group 162 has a negative refractive power as a whole, and performs a zooming action by moving on the optical axis. The third lens group 163 includes a lens having a positive refractive power and a lens having a negative refractive power, has a positive refractive power as a whole, and is fixed in the optical axis direction during zooming and focusing. It is in the state where it was. The fourth lens group 164 includes a lens having a negative refractive power and a lens having a positive refractive power, has a negative refractive power as a whole, and is fixed with respect to an image plane during zooming and focusing. It is in the state where it was. Fifth lens group 165
Has a positive refracting power as a whole, and moves on the optical axis to simultaneously move an image by zooming and adjust focus. In addition, when camera shake occurs, image shake is corrected by moving the third lens group 163 in a direction perpendicular to the optical axis.

Further, by introducing an aspherical surface to at least one surface of the lenses constituting the third lens group 163, the performance when the lens is shifted can be improved.

Further, the lenses of the third lens unit 163 having a positive refractive power have the same sag amount on the object-side surface and the image-side surface.

The values of the conditional expressions (Equation 52) to (Equation 70) for the zoom lens of this embodiment are shown below.

C1 = 16.96 mm, C2 = 15.94
mm, C3 = 14.60 mm C2 / C1 = 0.94 C3 / C1 = 0.86 r ₂₁₁ / r ₂₁₉ = 1.08 r ₃₁₁ / r ₃₁₉ = 0.82 r ₃₂₁ / r ₃₂₉ = 0.82 | f _{3 / f 34 | = 0.61 BF} / fw = 3.69 f 1 /fw=7.11 | f 2 | /fw=1.45 f 34 /fw=10.13 f 5 /fw=3.37 | Ν ₃₁ −ν ₃₂ | = 37.7 | ν ₄₁ −ν ₄₂ | = 36.8 nd ₃₁ = 1.51450 nd ₄₁ = 1.60311 | nd ₃₁ −nd ₃₂ | = 0.29 | nd ₄₁ −nd ₄₂ | = 0.24 St / Sw = 0.56 Yt = 0.25 Wide-angle end Y = 0.02 (Y / Yt) / (f / ft) = 0.78 Standard position Y = 0.11 (Y / Yt) / (f / ft) = 1.00 As is clear from the aberration performance diagrams shown in FIGS.
The zoom lens according to the present embodiment has sufficient aberration correction capability to realize high resolution.

FIG. 20 shows an aberration performance chart at the time of correcting a camera shake of 0.30 ° at the telephoto end. In FIG. 20,
(F), (g), and (h) are relative image heights of 0.75,
The lateral aberration is shown at the center of the screen and at a relative image height of -0.75. The solid line is the d line, the short broken line is the F line, and the long broken line is the C line.
The values for the lines are shown.

As is clear from FIG. 20, the zoom lens of this embodiment has good aberration performance even at the time of camera shake correction.

[Fourth Embodiment] In the present embodiment, a lens having a negative refractive power and a lens having a positive refractive power constituting the fourth lens group are separated. Further, at least one surface of the second lens group and the third lens group is aspheric.

(Example 5) The following (Table 13) shows specific numerical examples of the zoom lens according to the present example.

[0107]

[Table 13]

In Table 13 above, r is the radius of curvature of the lens surface, d is the thickness of the lens or the air gap between the lenses,
n is the refractive index of each lens with respect to the d line, and ν is the d of each lens.
Shows the Abbe number for the line.

The following (Table 14) shows the aspherical coefficients of the zoom lens of this embodiment.

[0110]

[Table 14]

The following Table 15 shows the values of the air gap (mm) that can be varied by zooming when the object point is at a position 2 m from the front end of the lens.

[0112]

[Table 15]

The standard position in the above (Table 15) is the second position.
This is the position where the magnification of the lens group becomes -1. In Table 15 above, f (mm), F / No, and ω (degree) are the focal length, F number, and incidence at the wide angle end, the standard position, and the telephoto end of the zoom lens of Table 13 above, respectively. The angle of view is half.

FIG. 21 shows a configuration diagram of a zoom lens based on the above data (Table 13), and FIGS. 22 to 24 show aberration performance diagrams of the present zoom lens at the wide angle end, the standard position, and the telephoto end. 22 to 24,
(A), (b), (c), (d), and (e) are spherical aberration (mm), astigmatism aberration (mm), distortion (%), axial chromatic aberration (mm), and chromatic aberration of magnification, respectively. (Mm). Further, in the diagram of the spherical aberration in each diagram (a),
The solid line shows the value for the d line. Each figure (b)
In the diagram of astigmatism, the solid line indicates sagittal field curvature and the broken line indicates meridional field curvature. Further, in the axial chromatic aberration of each figure (d), the solid line is the d line,
The short broken line shows the value for the F line, and the long broken line shows the value for the C line. Further, in the graph of the chromatic aberration of magnification in each figure (e), a short broken line indicates a value for the F line, and a long broken line indicates a value for the C line.

As shown in FIG. 21, the zoom lens of this embodiment is arranged in order from the object side to the image plane side.
It includes a first lens group 211, a second lens group 212, a third lens group 213, a fourth lens group 214, and a fifth lens group 215. A variable stop is arranged on the optical axis between the second lens group 212 and the third lens group 213.
The first lens group 211 has a positive refractive power as a whole,
It is fixed to the image plane during zooming and during focusing. The second lens group 212 has a negative refractive power as a whole, and performs a zooming action by moving on the optical axis. The third lens group 213 includes a lens having a positive refractive power and a lens having a negative refractive power, has a positive refractive power as a whole, and is fixed with respect to the optical axis direction at the time of zooming and focusing. It is in the state where it was. The fourth lens group 214 is composed of a lens having a positive refractive power and a lens having a negative refractive power, which are separated from each other, has a negative refractive power as a whole, and is located on the image surface during zooming and focusing. In a fixed state. Fifth
The lens group 215 has a positive refractive power as a whole, and moves on the optical axis to simultaneously move an image by zooming and adjust focus. In addition, when camera shake occurs, the image shake is corrected by moving the third lens group 213 in a direction perpendicular to the optical axis.

The lenses of the third lens unit 213 having a positive refractive power have the same sag amount on the object-side surface and the image-side surface.

The values of the conditional expressions (Equation 52) to (Equation 70) for the zoom lens of this embodiment are shown below.

C1 = 17.80 mm, C2 = 17.44
mm, C3 = 16.20 mm C2 / C1 = 0.98 C3 / C1 = 0.91 r ₂₁₁ / r ₂₁₉ = 1.03 r ₃₁₁ / r ₃₁₉ = 0.61 | f ₃ / f ₃₄ | = 0.65 _{BF / fw = 3.70 f 1 /fw=7.13} | f 2 | /fw=1.45 f 34 /fw=9.17 f 5 /fw=3.35 | ν 31 -ν 32 | = 37 0.7 | ν ₄₁ −ν ₄₂ | = 36.8 nd ₃₁ = 1.51450 nd ₄₁ = 1.60311 | nd ₃₁ −nd ₃₂ | = 0.29 | nd ₄₁ −nd ₄₂ | = 0.24 St / Sw = 0.83 Yt = 0.21 Wide-angle end Y = 0.01 (Y / Yt) / (f / ft) = 0.48 Standard position Y = 0.09 (Y / Yt) / (f / ft) = 1.03 As is clear from the aberration performance diagrams shown in FIGS.
The zoom lens according to the present embodiment has sufficient aberration correction capability to realize high resolution.

FIG. 25 is a graph showing aberration performance at the telephoto end at the time of 0.25 ° camera shake correction. In FIG. 25,
(F), (g), and (h) are relative image heights of 0.75,
The lateral aberration is shown at the center of the screen and at a relative image height of -0.75. The solid line is the d line, the short broken line is the F line, and the long broken line is the C line.
The values for the lines are shown.

As is clear from FIG. 25, the zoom lens of this embodiment has good aberration performance even at the time of camera shake correction.

FIG. 26 shows a state of the outer peripheral portion of the first lens group. By black-painting the second lens from the object side or attaching a light-shielding sheet to the lens, light rays passing through the outer periphery of the lens are cut.

FIG. 27 is a configuration diagram of a three-panel video camera equipped with a camera shake correction function, which is configured using the zoom lens of the present invention.

In FIG. 27, reference numeral 271 denotes the zoom lens described in the first embodiment. 272, a low-pass filter; 273a to 273c, prisms for color separation;
a to c are imaging devices. This video camera has a signal processing circuit 275, a viewfinder 2
76, a sensor 277 for detecting camera shake, and an actuator 278 for driving a lens.

Although not shown, the zoom lens described in the second to fourth embodiments can be used in place of the zoom lens described in the first embodiment.

In each of the above embodiments, the camera shake is corrected by shifting the lens group having a positive refractive power. However, the same applies to the case where the lens group having a negative refractive power is shifted. The effect is obtained.

[0126]

As described above, according to the present invention,
A zoom lens equipped with a camera shake correction function by shifting the third lens group can be realized. In addition, it has good aberration performance even when stopping and when shaking,
A zoom lens equipped with a camera shake correction function can be realized. Further, by using the zoom lens of the present invention, a high-performance video camera capable of correcting camera shake can be realized.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of a zoom lens equipped with a camera shake correction function according to the present invention.

FIG. 2 is a configuration diagram showing a zoom lens according to the first embodiment of the present invention.

FIG. 3 is an aberrational performance diagram at a wide-angle end of Example 1 according to the first embodiment of the present invention.

FIG. 4 is an aberration performance diagram at a standard position in Example 1 according to the first embodiment of the present invention.

FIG. 5 is an aberration performance diagram at the telephoto end of Example 1 according to the first embodiment of the present invention.

FIG. 6 is an aberration performance diagram at the time of correcting a camera shake at a telephoto end in Example 1 according to the first embodiment of the present invention.

FIG. 7 is an aberrational performance diagram at the wide-angle end of Example 2 according to the first embodiment of the present invention.

FIG. 8 is an aberration performance diagram at a standard position in Example 2 according to the first embodiment of the present invention.

FIG. 9 is an aberrational performance diagram at the telephoto end of Example 2 according to the first embodiment of the present invention.

FIG. 10 is a second example according to the first embodiment of the present invention.
Of aberrations at the telephoto end of a camera during camera shake correction

FIG. 11 is a configuration diagram showing a zoom lens according to a second embodiment of the present invention.

FIG. 12 is a third example according to the second embodiment of the present invention.
Of aberration performance at wide-angle end

FIG. 13 is a third example according to the second embodiment of the present invention.
Of aberration performance at standard position

FIG. 14 is a third example according to the second embodiment of the present invention.
Of aberration performance at the telephoto end

FIG. 15 is a third example according to the second embodiment of the present invention.
Of aberrations at the telephoto end of a camera during camera shake correction

FIG. 16 is a configuration diagram showing a zoom lens according to a third embodiment of the present invention.

FIG. 17 is a fourth example according to the third embodiment of the present invention.
Of aberration performance at wide-angle end

FIG. 18 is a fourth example according to the third embodiment of the present invention.
Of aberration performance at standard position

FIG. 19 is a fourth example according to the third embodiment of the present invention.
Of aberration performance at the telephoto end

FIG. 20 is a fourth example according to the third embodiment of the present invention.
Of aberrations at the telephoto end of a camera during camera shake correction

FIG. 21 is a configuration diagram showing a zoom lens according to a fourth embodiment of the present invention.

FIG. 22 is a fifth example of the fourth embodiment of the present invention.
Of aberration performance at wide-angle end

FIG. 23 is a fifth example of the fourth embodiment of the present invention.
Of aberration performance at standard position

FIG. 24 is a fifth example of the fourth embodiment of the present invention.
Of aberration performance at the telephoto end

FIG. 25 is a fifth example of the fourth embodiment of the present invention.
Of aberrations at the telephoto end of a camera during camera shake correction

FIG. 26 is a schematic view showing a peripheral portion of a first lens group according to the present invention.

FIG. 27 is a configuration diagram showing a video camera using the zoom lens according to the present invention.

[Explanation of symbols]

 21, 111, 161, 211 First lens group 22, 112, 162, 212 Second lens group 23, 113, 163, 213 Third lens group 24, 114, 164, 214 Fourth lens group 25, 115, 165, 215 Fifth lens group 271 Zoom lens 272 Low pass filter 273a-c Color separation prism 274a-c Image sensor 275 Signal processing circuit 276 Viewfinder 277 Sensor for detecting camera shake 278 Actuator

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H087 KA03 MA16 NA01 PA08 PA09 PA16 PA20 PB14 QA02 QA07 QA12 QA21 QA25 QA34 QA41 QA46 RA05 RA13 RA32 RA41 RA44 RA48 SA43 SA47 SA49 SA53 SA55 SA63 SA72 SA75 SB04 SB15 SB24 SB33 SB44 AB55 AB66 AC41 AC54 AC69 AC74 AC78

Claims (19)

[Claims] 1. A first lens having a positive refractive power and fixed to an image plane, which is arranged in order from an object side to an image plane side.
A lens group, a second lens group having a negative refractive power and performing a zooming operation by moving on the optical axis, and a positive lens power, and having a positive refractive power in the optical axis direction during zooming and focusing. A third lens group fixed to the optical axis, a fourth lens group having a negative refractive power and fixed with respect to the image plane, and having a positive refractive power on the optical axis of the second lens group. A fifth lens group that moves on the optical axis so as to keep the image plane that fluctuates with the movement of the object and the movement of the object at a fixed position from the reference plane,
The first lens group includes a lens having a negative refractive power, a first lens having a positive refractive power, and a second lens arranged in order from the object side.
Wherein the second lens group is a lens having a first negative refractive power, which is arranged in order from the object side;
The third lens group includes a second lens having a negative refractive power and a lens having a positive refractive power, and the third lens group is arranged in order from the object side and has a positive refractive power lens and a negative meniscus lens. And the whole thereof can be moved in a direction perpendicular to the optical axis in order to correct the movement of the image due to camera shake. The fourth lens group has a negative refractive power, which is arranged in order from the object side. The fifth lens group includes, in order from the object side, a lens having a negative refractive power, a first lens having a positive refractive power, and a second lens having a positive refractive power. A lens having a positive refractive power of
The effective diameter of the first lens from the object side of the lens group is C
1. When the effective diameter of the second lens from the object side of the first lens group is C2 and the effective diameter of the third lens from the object side of the first lens group is C3, the first lens group Satisfies the following conditional expressions (Equation 1) and (Equation 2). [Equation 1] 0.80 <C2 / C1 <1.00 [Equation 2] 0.65 <C3 / C1 <1.00 2. A first lens having a positive refractive power and fixed to an image plane, which is arranged in order from the object side to the image plane side.
A lens group, a second lens group having a negative refractive power and performing a zooming operation by moving on the optical axis, and a positive lens power, and having a positive refractive power in the optical axis direction during zooming and focusing. A third lens group fixed to the third lens group, a fourth lens group fixed to the image plane having a negative refractive power as a whole, and having a positive refractive power;
A fifth lens group that moves on the optical axis so that an image plane that fluctuates with the movement of the second lens group on the optical axis and the movement of an object is kept at a fixed position from a reference plane. Wherein the first lens group includes a lens having a negative refractive power, a lens having a first positive refractive power, and a lens having a second positive refractive power, arranged in order from the object side, The second lens group includes a lens having a first negative refractive power, a lens having a second negative refractive power, and a lens having a positive refractive power, which are arranged in order from the object side. A lens having a positive refractive power and a lens having a flat negative refractive power on the image side, which are arranged in order from the object side, and with respect to the optical axis in order to correct image movement due to camera shake. The whole is movable in a vertical direction, and the fourth lens group is arranged in order from the object side And a negative refractive power of the lens and the positive refractive power of the lens of the cemented lens, the fifth lens group,
A lens having a negative refractive power, which is arranged in order from the object side,
A lens having a positive refractive power and a lens having a second positive refractive power, wherein the effective diameter of the first lens from the object side of the first lens group is C1, and the effective diameter of the first lens from the object side of the first lens group is Second
Assuming that the effective diameter of the third lens is C2 and the effective diameter of the third lens from the object side of the first lens group is C3, the first lens group has the following conditions (Equation 3) and (Equation 4) A zoom lens that satisfies the formula. [Equation 3] 0.80 <C2 / C1 <1.00 [Equation 4] 0.65 <C3 / C1 <1.00 3. A first lens having a positive refractive power and fixed to the image plane, which is arranged in order from the object side to the image plane side.
A lens group, a second lens group having a negative refractive power and performing a zooming operation by moving on the optical axis, and a positive lens power, and having a positive refractive power in the optical axis direction during zooming and focusing. A third lens group fixed to the optical axis, a fourth lens group having a negative refractive power and fixed with respect to the image plane, and having a positive refractive power on the optical axis of the second lens group. A fifth lens group that moves on the optical axis so as to keep the image plane that fluctuates with the movement of the object and the movement of the object at a fixed position from the reference plane,
The first lens group includes a lens having a negative refractive power, a first lens having a positive refractive power, and a second lens arranged in order from the object side.
Wherein the second lens group is a lens having a first negative refractive power, which is arranged in order from the object side;
The third lens group includes a second lens having a negative refractive power and a lens having a positive refractive power, and the third lens group is a biconcave lens having a positive refractive power and a negative refractive power arranged in order from the object side. And the whole thereof is movable in a direction perpendicular to the optical axis to correct the movement of the image due to camera shake, and the fourth lens group is arranged in order from the object side,
The fifth lens group is composed of a cemented lens of a lens having a negative refractive power and a lens having a positive refractive power, and the fifth lens group is a lens having a negative refractive power and a lens having a first positive refractive power arranged in order from the object side. , And a second lens having a positive refractive power, wherein the effective diameter of the first lens from the object side of the first lens group is C1,
When the effective diameter of the second lens from the object side of the first lens group is C2 and the effective diameter of the third lens from the object side of the first lens group is C3, the first lens group is A zoom lens that satisfies the conditional expressions (5) and (6). [Equation 5] 0.80 <C2 / C1 <1.00 [Equation 6] 0.65 <C3 / C1 <1.00 4. A first lens having a positive refractive power and fixed to the image plane, which is arranged in order from the object side to the image plane side.
A lens group, a second lens group having a negative refractive power and performing a zooming operation by moving on the optical axis, and a positive lens power, and having a positive refractive power in the optical axis direction during zooming and focusing. A third lens group fixed to the optical axis, a fourth lens group having a negative refractive power and fixed with respect to the image plane, and having a positive refractive power on the optical axis of the second lens group. A fifth lens group that moves on the optical axis so as to keep the image plane that fluctuates with the movement of the object and the movement of the object at a fixed position from the reference plane,
The first lens group includes a lens having a negative refractive power, a first lens having a positive refractive power, and a second lens arranged in order from the object side.
Wherein the second lens group is a lens having a first negative refractive power, which is arranged in order from the object side;
The third lens group includes a second lens having a negative refractive power and a lens having a positive refractive power, and the third lens group includes a lens having a positive refractive power and a lens having a negative refractive power arranged in order from the object side. In addition, the entirety can be moved in a direction perpendicular to the optical axis to correct the movement of the image due to camera shake.
The lens group is arranged in order from the object side, and is composed of a separated negative refractive power lens and a positive refractive power lens, and the fifth lens group is arranged in order from the object side,
A lens having a negative refractive power, a first positive refractive power lens, and a second positive refractive power lens, wherein the effective diameter of the first lens from the object side of the first lens group is C1, The first
The effective diameter of the second lens from the object side of the lens group is C
2. When the effective diameter of the third lens from the object side of the first lens group is C3, the first lens group satisfies the following conditional expressions (7) and (8). And zoom lens. [Equation 7] 0.80 <C2 / C1 <1.00 [Equation 8] 0.65 <C3 / C1 <1.00 5. The zoom lens according to claim 1, wherein at least one surface of the lens constituting the second lens group is aspheric. 6. The zoom lens according to claim 1, wherein at least one surface of the lens constituting the third lens group is an aspheric surface. 7. In the i-th aspherical surface of the second lens group, the local radius of curvature at 10% of the effective lens diameter is r _2i1 , and the local radius of curvature at 90% of the effective lens diameter is The zoom lens according to any one of claims 1 to 7, which satisfies the following conditional expression when r _2i9 is satisfied. [ _Equation 9] 0.70 <r _2i1 / r _2i9 <1.60 8. In the i-th aspherical surface of the third lens group, the local radius of curvature at 10% of the lens effective diameter is r _3i1 , and the local radius of curvature at 90% of the lens effective diameter is The zoom lens according to any one of claims 1 to 7, which satisfies the following conditional expression when r _3i9 is satisfied. [ _Equation 10] 0.05 <r _3i1 / r _3i9 <2.00 9. The sag amount of a lens having a positive refractive power of the third lens group on the object side surface and the image surface side thereof is equal.
9. The zoom lens according to any one of items 1 to 8. 10. The focal length of the third lens group is f ₃ ,
When the combined focal length of the third lens group and the fourth lens group and f _34, according to claim 1, wherein the third lens group satisfies the following conditional expression (11) Zoom lens. [Equation 11] 0.30 <| f ₃ / f ₃₄ | <0.95 11. The focal length of the entire system at the wide-angle end is represented by f
The zoom lens according to any one of claims 1 to 10, wherein w is a distance from the last surface of the lens to the image forming surface in the air is BF, and the following conditional expression (12) is satisfied. [Equation 12] 2.0 <BF / fw <5.0 12. The focal length of the entire system at the wide-angle end is represented by f
w, the focal length of the i-th lens unit is f _i (i = 1 to 5), and the combined focal length of the third lens unit and the fourth lens unit is f _34.
The zoom lens according to claim 1, wherein the following conditional expressions (Equation 13) to (Equation 16) are satisfied. [Equation 13] 5.0 <f ₁ /fw<8.0 [Equation 14] 0.5 <| f ₂ | / fw <1.6 [Equation 15] 7.0 <f ₃₄ /fw<13.5 [Equation 16] 2.0 <f ₅ /fw<5.0 13. Abbe number [nu ₃₁ of one of the lenses of the third lens group, the Abbe number [nu ₃₂ of the other lens of said third lens group, the Abbe number of the one of the lenses of the fourth lens group The zoom according to any one of claims 1 to 12, wherein, when ν ₄₁ and Abbe number of the other lens in the fourth lens group are ν ₄₂ , the following conditional expressions (Equation 17) and (Equation 18) are satisfied. lens. [Equation 17] | ν ₃₁ −ν ₃₂ |> 25 [Equation 18] | ν ₄₁ −ν ₄₂ |> 25 14. The lens of the third lens group having a positive refractive power has a refractive index of nd ₃₁ , the lens of the third lens group having a negative refractive power has a refractive index of nd ₃₂ , and the refractive index of the lens of the third lens group has a negative refractive power of nd ₃₂ . Assuming that the refractive index of the lens having a refractive power of nd ₄₁ is nd ₄₁ and the refractive index of the lens having a positive refractive power of the fourth lens group is nd ₄₂ , the following conditional expressions (Equation 19) to (Equation 22) are satisfied Claims 1 to 13
The zoom lens according to any one of the above. [Expression 19] nd ₃₁ <1.60 [Expression 20] nd ₄₁ > 1.50 [Expression 21] | nd ₃₁ −nd ₃₂ |> 0.25 [Expression 22] | nd ₄₁ −nd ₄₂ |> 0.20 15. An aperture fixed to an image plane is provided on the object side of the third lens group. The aperture diameter of the aperture decreases as the focal length of the entire system increases, and the aperture diameter at the telephoto end is reduced. The zoom lens according to any one of claims 1 to 14, wherein, when St and the aperture diameter at the wide-angle end are Sw, the following conditional expression (23) is satisfied. [Equation 23] St / Sw <0.92 16. The method according to claim 1, wherein a ray passing through the outer peripheral portion of the lens is cut by applying black ink or attaching a light-shielding sheet to the second lens from the object side of the first lens group. The zoom lens described. 17. The zoom lens according to claim 1, wherein when the ratio of movement of the image on the screen during camera shake correction changes from wide angle to telephoto, the zoom lens increases in proportion to the zoom ratio. 18. The maximum movement amount of the third lens group at the focal length f of the entire system at the time of camera shake correction is Y, the movement amount of the third lens group at the telephoto end is Yt, and the focal length at the telephoto end is ft. 17. The zoom lens according to claim 1, wherein the following conditional expressions (Expression 24) and (Expression 25) are satisfied. [Equation 24] Yt> Y [Equation 25] (Y / Yt) / (f / ft) <1.5 19. A video camera using the zoom lens according to claim 1.