JPH11344669A - Zoom lens and video camera using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom lens which is small-sized and compact by composing the zoom lens of five groups so that a 3rd and a 4th lens each consist of two lens elements, and correcting a hand shake by moving one of the lens groups perpendicularly to the optical axis. SOLUTION: The zoom lens has a 1st lens group 21 which has positive refracting power and is fixed on an image plane, a 2nd lens group 22 which has negative refracting power and moves on the optical axis to vary the power, the 3rd lens group 23 which is fixed on the image plane and consists of two lens elements and has positive refracting power, the 4th lens group 24 which is fixed on the image plane and consists of two lens elements and has negative refracting power, and a 5th lens group 25 which has positive refracting power and moves on the optical axis so as to hold the image plane moving as the 2nd lens group 22 moves and a body moves at a fixed position about a reference surface in order from the object side and corrects the movement of an image in case of a hand shake by moving the 3rd lens group 23 at right angles to the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens 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 shooting system such as a video camera,
An anti-shake function for preventing vibration such as camera shake is essential, and various types of anti-shake optical systems have been proposed.

[0003] For example, a zoom lens proposed in Japanese Patent Application Laid-Open No. Hei 8-29737 has a front surface of a zoom lens.
An image movement caused by camera shake is corrected by mounting an optical system for image stabilization having a single image structure and moving any one of the optical systems perpendicularly to the optical axis.

A zoom lens proposed in Japanese Patent Application Laid-Open No. Hei 7-128619 is a zoom lens having a four-group configuration, in which a part of a third group composed of a plurality of lenses is partially moved with respect to the optical axis. The vertical movement corrects the movement of the image due to camera shake.

[0005]

However, the zoom lens proposed in Japanese Patent Application Laid-Open No. H8-29737 has a camera shake correction optical system mounted on the front surface of the zoom lens. Lens diameter becomes large. Accompanying this, the entire apparatus becomes large, and the load on the drive system also increases, which is disadvantageous for miniaturization, light weight, and power saving.

A zoom lens proposed in Japanese Patent Application Laid-Open No. Hei 7-128619 has an image caused by camera shake by moving a part of a third lens group fixed to an image plane perpendicularly to an optical axis. Is more advantageous in terms of size compared to the type mounted on the front of the lens,
Since the lens group for camera shake correction consists of three lenses,
The burden on the actuator was heavy.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. A third lens group and a fourth lens group fixed to an image plane during zooming and focusing in a fifth group zoom lens are provided. The objective of the present invention is to provide a small and compact zoom lens with little deterioration in aberration performance by correcting one hand movement by moving one group perpendicularly to the optical axis.

[0008]

To achieve the above object, a zoom lens according to the present invention comprises, in order from the object side, a first lens group having a positive refractive power and fixed to an image plane; A second lens group having a refracting power and moving on the optical axis and having a zooming action, a third lens group having a two-element configuration fixed to the image plane, and fixed to the image plane. A fourth lens unit having a two-lens configuration, and having a positive refractive power that moves on the optical axis so that an image plane that fluctuates due to the movement of the second lens group and the movement of an object is kept at a fixed position from the reference plane. A fifth lens group, wherein the third lens group and the fourth lens group are a combination of a lens group having a positive refractive power and a lens group having a negative refractive power; The fourth
By moving one of the lens groups perpendicular to the optical axis, the movement of the image at the time of camera shake is corrected.

According to the above-described zoom lens, camera shake is corrected by moving a lens having a small diameter, so that the size of the zoom lens can be reduced as compared with a type in which an optical system for camera shake correction is mounted on the front of the lens. This is advantageous, and the aberration performance can be adjusted for each lens group, so that the deterioration of the aberration performance is small even at the time of camera shake correction.

In the zoom lens, the third lens group is a lens group having a positive refractive power, and the fourth lens group is a lens group having a positive refractive power.
Preferably, the lens group is a lens group having a negative refractive power, and the third lens group is moved perpendicularly to the optical axis to correct the movement of the image during camera shake. According to the above-described zoom lens, since a lens unit having a negative refractive power is disposed in the fourth lens unit, a long back focus is easily ensured, and an optical system requiring a long back focus such as three plates is required. Suitable for.

Further, the third lens group is a lens group having a negative refractive power, the fourth lens group is a lens group having a positive refractive power, and the fourth lens group is perpendicular to an optical axis. It is preferable to correct the movement of the image due to camera shake by moving it. According to the zoom lens as described above, the fourth
Since the lens group having a positive refractive power is arranged in the lens group, the light incident on the fifth lens group can be reduced, so that the lens diameter can be reduced. Therefore, the burden on the focus actuator can be reduced.

It is preferable that, of the third lens group and the fourth lens group, a lens group for correcting a movement of an image due to a camera shake by moving the lens group perpendicularly to an optical axis is a cemented lens. . According to the above-described zoom lens, the tolerance at the time of assembling the correction lens group can be relaxed.

In each of the zoom lenses, the Abbe number of one lens of the third lens group is ν31, the Abbe number of the other lens is ν32, and the Abbe number of one lens of the fourth lens group is ν41. The Abbe number of the other lens is ν42
Then, it is preferable to satisfy the following relationship: | ν31−ν32 |> 25 | ν41−ν42 |> 25 According to the above-described zoom lens, a sufficient achromatizing effect can be provided, so that deterioration of chromatic aberration of magnification can be reduced even during lens shift.

In the third lens group and the fourth lens group, at least one aspherical surface is included in a lens group that is moved perpendicular to an optical axis to correct the movement of an image due to camera shake. Is preferred. According to the zoom lens as described above, the performance at the time of lens shift can be improved.

In the third lens group and the fourth lens group, a convex lens included in a lens group for correcting a movement of an image due to camera shake by moving the lens perpendicular to an optical axis includes an object side lens. Assuming that the surface is aspherical and the local radius of curvature at 10% of the effective lens diameter is rS1, and the local radius of curvature at 90% of the effective diameter is rS9, 0.01 <r
It is preferable to satisfy the relationship of S1 / rS9 <2.00.
According to the zoom lens as described above, sufficient aberration performance can be obtained.

The focal length of a lens group of the third lens group and the fourth lens group which is moved perpendicular to the optical axis to correct the movement of an image due to camera shake is f.
S, if the combined focal length of the third and fourth lens groups is f34, 0.40 <| fs / f34 | <0.85
Is preferably satisfied. According to the zoom lens as described above, since the power of the correction lens can be suppressed, the deterioration of the aberration performance can be prevented, and the movement amount of the lens at the time of camera shake correction can also be suppressed.
The lens diameter can be reduced, which is advantageous for miniaturization.

The focal length of the entire system at the wide-angle end is represented by f
w, assuming that the distance from the last surface of the lens to the image forming surface in the air is BF, it is preferable to satisfy a relationship of 2.0 <BF / fw <5.0. According to the above-described zoom lens, a zoom lens having a long back focus can be realized.

The focal length of the entire system at the wide-angle end is represented by f
w, the focal length of the ith lens group is fi (i = 1 to 5),
Assuming that the lens group, the fourth lens group, and the combined focal length are f34, 5.0 <f1 / fw <8.0 0.5 <| f2 | / fw <1.6 4.0 <f34 / fw <9. It is preferable to satisfy the relationship of 5 2.0 <f5 / fw <5.0. According to the zoom lens as described above, the zoom lens can be made compact.

If the amount of movement of the correction lens at the focal length f of the entire system at the time of camera shake correction is Y, the amount of movement of the correction lens at the telephoto end is Yt, and the focal length at the telephoto end is ft, Yt> Y (Y It is preferable to satisfy the relationship of /Yt)/(f/ft)<1.5. According to the above-described zoom lens, overcorrection can be prevented, and deterioration of optical performance can be prevented.

Next, the video camera of the present invention uses each of the zoom lenses. For this reason, a compact and high-performance video camera with a camera shake correction function can be obtained.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a zoom lens according to the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows a basic configuration diagram of a zoom lens according to Embodiment 1 of the present invention. A first lens group 1 having a positive refractive power and fixed to an image plane, and a second lens having a negative refractive power and having a variable power function by moving on the optical axis in order from the object side. Group 2, a third lens group 3 having a positive refractive power fixed to the image plane, a fourth lens group 4 having a negative refractive power fixed to the image plane, and a second lens group. A fifth lens group 5 having a positive refractive power that moves on the optical axis such that an image plane that fluctuates due to movement and movement of the object is kept at a fixed position from the reference plane. Camera shake correction is performed by shifting the third lens group having a positive refractive power in a direction perpendicular to the optical axis. FIG. 2 shows FIG.
Is a zoom lens having the basic configuration shown in FIG. The first lens group 21, the second lens group 22, the third lens group 23, the fourth lens group 24, and the fifth lens group 25 are arranged in this order from the object side to the image plane.

The first lens group 21 has a positive refractive power and is fixed with respect to the image plane during zooming and focusing.
The second lens group 22 has a negative refracting power and performs a zooming action by moving on the optical axis. The third lens group 23 is
It is composed of a positive lens and a negative lens and has a positive refractive power as a whole. The fourth lens group 24 includes a negative lens and a positive lens, has a negative refractive power as a whole, and is fixed to the image plane at the time of zooming and at the time of focusing. Fifth
The lens group 25 has a positive refractive power and moves on the optical axis, thereby simultaneously moving the image by zooming and adjusting the focus. When camera shake occurs, the image shake is corrected by moving the third lens group 23 in a direction orthogonal to the optical axis.

By combining the third lens group 23 having a positive refractive power and the fourth lens group 24 having a negative refractive power as in this embodiment, the amount of movement of the shift lens group during camera shake correction can be reduced. , And the back focus can be lengthened. In particular, since a lens group having a negative refractive power is arranged on the image plane side, it is easy to secure a long back focus.

Further, by introducing at least one aspherical surface into one of the lenses of the third lens group, the performance when the lens is shifted can be improved, and the zoom lens can be reduced in size and improved in performance. Can be achieved simultaneously.

The Abbe number of one lens of the third lens group is ν31, the Abbe number of the other lens is ν32, the Abbe number of one lens of the fourth lens group is ν41, and the Abbe number of the other lens is ν42. And the following equations (A) and (B)
Is preferably satisfied. Expression (A) | ν31−ν32 |> 25 Expression (B) | ν41−ν42 |> 25 If the expressions (A) and (B) are satisfied, it is possible to reduce deterioration of chromatic aberration of magnification during camera shake correction. At the time of camera shake correction due to lens shift, magnification chromatic aberration occurs,
By setting the Abbe number difference of each lens group as in the above equation, a sufficient achromatism effect can be provided, so that deterioration of lateral chromatic aberration can be reduced even during lens shift.

The object-side surface of the camera shake correction lens is an aspheric surface, the local radius of curvature at 10% of the effective diameter of the lens is rS1, and the local radius of curvature at 90% of the effective diameter is rS1. When the radius is rS9, it is preferable that the following formula (C) is satisfied.

Expression (C) 0.01 <rS1 / rS9 <2.00 Expression (C) is a conditional expression that defines the amount of aspherical surface, and has sufficient aberration performance to realize a high resolution of the zoom lens. It is an expression showing the conditions to obtain. In the formula (C), when the value exceeds the upper limit, 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 is below the lower limit, the correction amount of the spherical aberration becomes too large, and sufficient aberration performance cannot be obtained.

Here, the local radius of curvature C is a value obtained by algebraically calculating based on the aspherical coefficient calculated from the sag amount of the surface shape. It can be obtained by the equation (2).

[0029]

(Equation 1)

[0030]

(Equation 2)

SAG: distance from the aspherical vertex of a point on the aspherical surface at a height from the optical axis H: H: height from the optical axis R: radius of curvature of the aspherical vertex K: conical constant D: aspherical surface Coefficient E: Aspherical coefficient F: Aspherical coefficient G: Aspherical coefficient C: Local radius of curvature Further, fS is a focal length of the correction lens, and f34 is a combined focal length of the third lens group and the fourth lens group. It is preferable that the correcting lens satisfies the following expression (D). Equation (D) 0.40 <| fs / f34 | <0.85 Equation (D) is a conditional expression that defines the focal length of the lens for camera shake correction. In the formula (D), when the value goes below the lower limit, the power of the correcting lens becomes too strong, the deterioration of aberration performance becomes large, and the assembly tolerance at the time of manufacturing becomes strict.
On the other hand, if the upper limit is exceeded, the amount of movement of the lens at the time of camera shake correction becomes large, so that the lens diameter becomes large, which is disadvantageous for miniaturization.

More specifically, assuming that the focal length of the entire system at the wide-angle end is fw and the distance between the last lens surface and the image forming surface in air is BF, the zoom lens satisfies the following equation (E). Is preferred. Expression (E) 2.0 <BF / fw <5.0 Expression (E) is a conditional expression for realizing a zoom lens having a long back focus such as three plates. If the lower limit is exceeded, a color separation optical system having a length as long as sufficient color separation cannot be inserted. Beyond the upper limit, the back focus becomes longer than necessary, making it impossible to make it compact.

The focal length of the entire system at the wide-angle end is represented by f
w, the focal length fi of the i-th lens group (i = 1 to 5),
When the combined focal length of the lens unit and the fourth lens unit is f34, it is preferable that the following expressions (F) to (I) are satisfied.

Equation (F) 5.0 <f1 / fw <8.0 Equation (G) 0.5 <| f2 | / fw <1.6 Equation (H) 4.0 <f34 / fw <9.5 Equation (I) 2.0 <f5 / fw <5.0 Equation (F) is a condition relating to the refractive power of the first lens group.
If the lower limit is exceeded, the refractive power of the first lens group becomes too large, and it becomes difficult to correct spherical aberration on the long focal length side. If the upper limit is exceeded, the lens length increases, and a compact zoom lens cannot be realized.

Equation (G) is a conditional expression relating to the refractive power of the second lens group. If the value falls outside the lower limit, the size can be made compact, but the Petzval sum of the entire system becomes negative and the field curvature cannot be corrected. Above the upper limit, aberration correction is easy, but the zooming system becomes longer and the entire system cannot be made compact.

Equation (H) is a condition for the refractive power of the third lens group. If the lower limit is exceeded, the refractive power of the third lens group becomes too large, so that it becomes difficult to correct spherical aberration. If the upper limit is exceeded, the combined system of the first to third lens groups becomes a divergent system, so that the lens outer diameter of the fourth lens group located thereafter cannot be reduced, and the Petzval sum of the entire system is reduced. Can not do.

Equation (I) is a condition relating to the refractive power of the fourth lens group. If the value falls outside the lower limit, the comprehensive range of the screen 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 reduction in size and weight cannot be realized. Above the upper limit, aberration correction is easy, but the amount of movement of the fourth lens group during short-distance shooting increases, and not only the entire system cannot be made compact, but also during short-distance shooting and long-distance shooting. It is difficult to correct the imbalance of off-axis aberrations.

When the amount of movement of the correction lens at the focal length f of the entire system for camera shake correction is Y, the amount of movement of the correction lens at the telephoto end is Yt, and the focal length at the telephoto end is ft, the following equation (J ) And (K) are preferably satisfied.

Equation (J) Yt> Y Equation (K) (Y / Yt) / (f / ft) <1.5 Equations (J) and (K) are equations relating to the amount of movement of the correction lens. In the case of a zoom lens, when the correction angle is constant in the entire zoom range, the larger the zoom ratio, the larger the amount of movement of the correction lens, and conversely, the smaller the zoom ratio, the smaller the amount of movement of the correction lens. If the upper limits of the equations (J) and (K) are exceeded, the correction will be excessive, and the optical performance will be greatly deteriorated. (Embodiment 2) FIG. 3 shows a basic configuration of a zoom lens according to Embodiment 2. In order from the object side, a first lens group 1a having a positive refractive power and fixed to the image plane, and a second lens group having a negative refractive power and having a zooming effect by moving on the optical axis. A lens group 2a, a third lens group 3a having a negative refractive power fixed to the image plane, a fourth lens group 4a having a positive refractive power fixed to the image plane, A fifth lens group 5a having a positive refractive power that moves on the optical axis so that an image plane that fluctuates due to the movement of the lens group and the movement of the object is kept at a fixed position from the reference plane. The camera shake is corrected by shifting the fourth lens group having a positive refractive power in a direction perpendicular to the optical axis.

FIG. 4 shows an embodiment of a zoom lens having the basic configuration of FIG. The first lens group 121, the second lens group 122, the third lens group 123, and the fourth lens group 124 are arranged in this order from the object side toward the image plane. The first lens group 121 has a positive refractive power, and is fixed to the image plane during zooming and during focusing. The second lens group 122 has a negative refractive power and performs a zooming action by moving on the optical axis.

The third lens group 123 includes a negative lens and a positive lens, has a negative refractive power as a whole,
The lens group 124 includes a positive lens and a negative lens, has a positive refractive power as a whole, and is fixed to the image plane at the time of zooming and at the time of focusing. The fifth lens group 125 has a positive refractive power, and moves on the optical axis to simultaneously move the image by zooming and adjust the focus.

When a camera shake occurs, the image shake is corrected by moving the fourth lens group 124 in a direction perpendicular to the optical axis. In this way, by combining the third lens group 123 with a negative refractive power and the fourth lens group 124 with a positive refractive power, the ray height of the light beam incident on the fifth lens group 125 can be reduced. That is, by introducing at least one or more aspherical surfaces into any of the lenses of the fourth lens group, which can reduce the load on the actuator for focusing because the lens diameter of the fourth lens group can be reduced.
The performance when the lens is shifted can be improved. Further, as in the first embodiment, it is preferable to satisfy the expressions (A) to (K).

(Embodiment 3) FIG. 5 shows a configuration diagram of a zoom lens according to Embodiment 3. A first lens group 161, a second lens group 162, a third lens group 163, and a fourth lens group 164 are arranged in this order from the object side toward the image plane. The first lens group 161 has a positive refractive power, and is fixed to the image plane at the time of zooming and at the time of focusing. The second lens group 162 has a negative refractive power, and performs a zooming action by moving on the optical axis.

The third lens group 163 is a two-element cemented lens having a positive refractive power, and the fourth lens group 164 has a negative refractive power. Is fixed. The fifth lens group 165 has a positive refractive power,
By moving on the optical axis, movement of an image by zooming and adjustment of focus are performed simultaneously. When camera shake occurs, the third
By moving the lens group 163 in a direction perpendicular to the optical axis, image blur is corrected. Shift lens group 1
By using the cemented lens 63, the tolerance can be reduced.

By introducing at least one aspheric surface into any of the lenses of the third lens group, the performance when the lens is shifted can be improved. Further, similarly to the first embodiment, it is preferable to satisfy the expressions (A) to (K).

(Embodiment 4) Embodiment 4 is a three-panel video camera equipped with a camera shake correction function using the zoom lens according to Embodiments 1 to 3, and FIG. 6 shows the configuration thereof.

The video camera according to the second embodiment includes the zoom lens 201 and the low-pass filter 20 according to the first embodiment.
2. Color separation prisms 203a to 203c, imaging device 2
04a to 204c, signal processing circuit 205, viewfinder 206, sensor 20 for detecting camera shake
7, and an actuator 2 for driving the lens
08.

Although not shown, the zoom lens 2
01 is not limited to the one in the first embodiment, but is the second or third embodiment.
May be used. In addition, the first embodiment
In Nos. 1 to 2, the shift lens group is composed of two single lenses, but the tolerance can be relaxed by using a cemented lens.

In the first to third 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 of is obtained.

[0050]

(Example 1) Example 1 is an example according to the first embodiment. Table 1 below shows specific numerical values of the zoom lens according to the first embodiment. In Table 1, r (m
m) is the radius of curvature of the lens surface, d (mm) 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 Abbe number of each lens with respect to the d-line (hereinafter, referred to as the following) The same applies to Tables 4, 7, 10, and 13).

[0051]

[Table 1]

The aspherical coefficients are shown in Table 2 below.

[0053]

[Table 2]

Table 3 below shows values at an object point at a position of 2 m measured from the front end of the lens as a variable air interval due to zooming. In Table 3, the standard position is a position at which the magnification of the second lens group becomes −1, f (mm), F / N
o and ω (°) are the wide-angle end of the zoom lens shown in Table 1, respectively.
The focal length, F number, and half angle of incidence at the standard position and the telephoto end (the same applies to Tables 6, 9, 12, and 15 below).

[0055]

[Table 3]

FIGS. 7 to 9 show aberration diagrams of the zoom lens at the wide-angle end, at the standard position, and at the telephoto end. FIG.
9 to 9, (a) is a diagram of spherical aberration, a solid line is a value for d-line, a dotted line is a sine condition, (b) is a diagram of astigmatism aberration, a solid line is sagittal field curvature, and a dotted line is meridional. (C) indicates distortion, and (d) indicates field curvature.
Is a diagram of axial chromatic aberration, a solid line is a value for the d-line, a dotted line is a value for the F-line, a wavy line is a value for the C-line, and (e) is a diagram of the chromatic aberration of magnification. (The same applies to FIGS. 10 to 21 below).

The values of equations (A) to (I) are shown below. | Ν31−ν32 | = 32.3 | ν41−ν42 | = 38.7 rS1 / rS9 = 0.52 | fs / f3 | = 0.64 BF / fw = 3.34 f1 / fw = 7.19 | f2 | /Fw=1.28 f34 / fw = 7.61 f5 / fw = 3.14 As is clear from the aberration diagrams shown in FIGS. 7 to 9, this embodiment is sufficient for realizing high resolution of the zoom lens. It has aberration correction ability.

In this embodiment, the above formulas (J) and (K) are used.
Is satisfied, the deterioration of the optical performance can be prevented. (Example 2) Example 2 is also an example according to the first embodiment. Table 4 below shows specific numerical values of the zoom lens according to the second embodiment.

[0059]

[Table 4]

The aspheric coefficients are shown in Table 5 below.

[0061]

[Table 5]

Table 6 below shows the value at an object point at a position 2 m from the lens tip as a variable air interval due to zooming.

[0063]

[Table 6]

FIGS. 10 to 12 show aberration diagrams of the zoom lens at the wide-angle end, at the standard position, and at the telephoto end. The values of the formulas (A) to (I) are shown below. | Ν31−ν32 | = 37.7 | ν41−ν42 | = 37.7 rS1 / rS9 = 0.07 | f3S / f3 | = 0.57 BF / fw = 3.29 f1 / fw = 7.22 | f2 | /Fw=1.28 f34 / fw = 8.40 f5 / fw = 3.15 As is clear from the aberration diagrams shown in FIGS. 10 to 12, in this embodiment, sufficient aberrations to realize a high resolution of the zoom lens are obtained. Has correction capability. Further, in the present embodiment, since the expressions (J) and (K) are satisfied, deterioration of optical performance can be prevented.

(Example 3) Example 3 is also the same as in the first embodiment.
This is an example according to the present invention. Table 7 below shows specific numerical values of the zoom lens according to the third embodiment.

[0066]

[Table 7]

The aspherical coefficients are shown in Table 8 below.

[0068]

[Table 8]

Table 9 below shows values at an object point at a position of 2 m measured from the front end of the lens as a variable air gap due to zooming.

[0070]

[Table 9]

FIGS. 13 to 15 show aberration diagrams of the zoom lens at the wide-angle end, at the standard position, and at the telephoto end. The values of the formulas (A) to (I) are shown below. | Ν31−ν32 | = 32.3 | ν41−ν42 | = 38.6 rS1 / rS9 = 0.58 | f3S / f3 | = 0.72 BF / fw = 2.93 f1 / fw = 6.97 | f2 | /Fw=1.26 f34 / fw = 5.89 f5 / fw = 3.11 As is clear from the aberration diagrams shown in FIGS. 13 to 15, in the present embodiment, a sufficient resolution for realizing high resolution of the zoom lens is obtained. It has aberration correction ability. Further, in the present embodiment, since the expressions (J) and (K) are satisfied, deterioration of optical performance can be prevented.

Example 4 Example 4 is different from Example 2 described above.
This is an example according to the present invention. That is, in the fourth embodiment, the third lens group includes a negative lens and a positive lens in order from the object side,
The fourth lens group has a negative refractive power as a whole, and the fourth lens group is composed of a positive lens and a negative lens in order from the object side. The fourth lens group has a positive refractive power as a whole, and moves the fourth lens group with respect to the optical axis during camera shake correction. The camera shake is corrected by moving the camera vertically.

Table 10 below shows specific numerical values of the zoom lens according to the fourth embodiment.

[0074]

[Table 10]

The aspherical coefficients are shown in Table 11 below.

[0076]

[Table 11]

Table 12 below shows values at an object point at a position of 2 m measured from the front end of the lens as a variable air gap due to zooming.

[0078]

[Table 12]

FIGS. 16 to 18 show aberration diagrams of the zoom lens at the wide-angle end, at the standard position, and at the telephoto end. The values of the formulas (A) to (I) are shown below. | Ν31−ν32 | = 40.2 | ν41−ν42 | = 32.3 rS1 / rS9 = 0.74 | f3S / f3 | = 0.69 BF / fw = 3.45 f1 / fw = 7.43 | f2 | /Fw=1.29 f34 / fw = 6.20 f5 / fw = 4.19 As is apparent from the aberration diagrams shown in FIGS. 16 to 18, in the present embodiment, a sufficient resolution for realizing the high resolution of the zoom lens is obtained. It has aberration correction ability. Further, in the present embodiment, since the expressions (J) and (K) are satisfied, deterioration of optical performance can be prevented.

Example 5 Example 5 is different from Example 3 described above.
This is an example according to the present invention. That is, in the fifth embodiment, the third lens group includes, in order from the object side, a cemented lens of a positive lens and a negative lens, and has a positive refractive power as a whole.

Table 13 below shows specific numerical values of the zoom lens according to Embodiment 5.

[0082]

[Table 13]

The aspherical coefficients are shown in Table 14 below.

[0084]

[Table 14]

Table 15 below shows values at an object point at a position of 2 m measured from the front end of the lens as a variable air spacing due to zooming.

[0086]

[Table 15]

FIGS. 19 to 21 show aberration diagrams of the zoom lens at the wide-angle end, at the standard position, and at the telephoto end. The values of the formulas (A) to (I) are shown below. | Ν31−ν32 | = 32.3 | ν41−ν42 | = 38.6 rS1 / rS9 = 1.49 | f3S / f3 | = 0.66 BF / fw = 3.36 f1 / fw = 7.21 | f2 | /Fw=1.29 f34 / fw = 7.35 f5 / fw = 2.96 As is clear from the aberration diagrams shown in FIGS. 19 to 21, in this embodiment, a sufficient resolution for realizing the high resolution of the zoom lens is obtained. It has aberration correction ability. Further, in the present embodiment, since the expressions (J) and (K) are satisfied, deterioration of optical performance can be prevented.

[0088]

As described above, according to the zoom lens of the present invention, since the camera shake is corrected by moving the small-diameter lens, the zoom lens is mounted on the front surface of the lens. It is advantageous for miniaturization compared to
Furthermore, since aberration performance can be adjusted for each lens group, deterioration of aberration performance is small even during camera shake correction.

Further, according to the video camera of the present invention, since the zoom lens of the present invention is used, 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 according to a first embodiment of the present invention.

FIG. 2 is a basic configuration diagram of a zoom lens according to Embodiment 1 of the present invention.

FIG. 3 is a basic configuration diagram of a zoom lens according to a second embodiment of the present invention.

FIG. 4 is a basic configuration diagram of a zoom lens according to a second embodiment of the present invention.

FIG. 5 is a basic configuration diagram of a zoom lens according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of an embodiment of a video camera of the present invention.

FIG. 7 is an aberration diagram at a wide-angle end according to the first embodiment of the present invention.

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

FIG. 9 is an aberration diagram at a telephoto end according to the first embodiment of the present invention.

FIG. 10 is an aberration diagram at a wide-angle end according to a second embodiment of the present invention.

FIG. 11 is an aberration diagram at a standard position according to the second embodiment of the present invention.

FIG. 12 is an aberration diagram at a telephoto end in Embodiment 2 of the present invention.

FIG. 13 is an aberration diagram at a wide angle end according to a third embodiment of the present invention.

FIG. 14 is an aberration diagram at a standard position according to the third embodiment of the present invention.

FIG. 15 is an aberration diagram at a telephoto end in Example 3 of the present invention.

FIG. 16 is an aberration diagram at a wide-angle end according to a fourth embodiment of the present invention.

FIG. 17 is an aberration diagram at a standard position in Example 4 of the present invention.

FIG. 18 is an aberration diagram at a telephoto end in Example 4 of the present invention.

FIG. 19 is an aberration diagram at a wide-angle end according to a fifth embodiment of the present invention.

FIG. 20 is an aberration diagram at a standard position in Example 5 of the present invention.

FIG. 21 is an aberration diagram at a telephoto end in Example 5 of the present invention.

[Explanation of symbols]

 1, 1a, 121, 161 First lens group 2, 2a, 122, 162 Second lens group 3, 3a, 123, 163 Third lens group 4, 4a, 124, 164 Fourth lens group 5, 5a, 125, 165 Fifth lens group 201 Zoom lens 202 Low-pass filter 203a, 203b, 203c Color separation prism 204a, 204b, 204c Image sensor 205 Signal processing circuit 206 Viewfinder 207 Sensor 208 Actuator

Claims (12)

[Claims] 1. A first lens group having a positive refractive power and fixed with respect to an image plane, and a first lens group having a negative refractive power and having a zooming effect by moving on an optical axis in order from the object side. A two-lens group, a third lens group having a two-lens configuration fixed to the image plane, a fourth lens group having a two-lens configuration fixed to the image plane, and movement of the second lens group; A fifth lens group having a positive refractive power that moves on the optical axis so as to keep an image plane that fluctuates due to the movement of the object at a constant position from the reference plane,
The third lens group and the fourth lens group may be a combination of a lens group having a positive refractive power and a lens group having a negative refractive power, and may be any one of the third lens group and the fourth lens group. A zoom lens wherein one of the lens groups is moved perpendicularly to an optical axis to correct the movement of an image during camera shake. 2. The third lens group is a lens group having a positive refractive power, the fourth lens group is a lens group having a negative refractive power, and the third lens group is perpendicular to an optical axis. 2. The method according to claim 1, wherein the movement of the image is corrected by moving the image.
A zoom lens according to claim 1. 3. The third lens group is a lens group having a negative refractive power, the fourth lens group is a lens group having a positive refractive power, and the fourth lens group is perpendicular to an optical axis. 2. The method according to claim 1, wherein the movement of the image is corrected by moving the image.
A zoom lens according to claim 1. 4. A cemented lens among the third lens group and the fourth lens group, wherein the lens group that moves perpendicular to the optical axis to correct the image movement during camera shake is a cemented lens. 4. The zoom lens according to any one of items 1 to 3. 5. The Abbe number of one lens of the third lens group is ν31, the Abbe number of the other lens is ν32,
5. The condition of | ν31−ν32 |> 25 | ν41−ν42 |> 25, wherein the Abbe number of one lens of the lens group is ν41 and the Abbe number of the other lens is ν42. A zoom lens according to claim 1. 6. A lens group of the third lens group and the fourth lens group which corrects movement of an image due to camera shake by moving perpendicularly to an optical axis includes at least one aspheric surface. The zoom lens according to claim 1. 7. A convex lens included in a lens group of the third lens group and the fourth lens group that corrects movement of an image due to camera shake by moving the lens perpendicular to an optical axis is an object side lens. If the surface is an aspheric surface and the local radius of curvature at 10% of the effective diameter of the lens is rS1 and the local radius of curvature at 90% of the effective diameter is rS9, 0.01 <rS1
The zoom lens according to any one of claims 1 to 6, which satisfies a relationship of /rs9<2.00. 8. The focal length of a lens group of the third lens group and the fourth lens group, which is moved perpendicular to an optical axis to correct image movement during camera shake, is fS. Let f34 be the composite focal length of the lens group and the fourth lens group.
The zoom lens according to any one of claims 1 to 7, wherein the following relationship is satisfied: 0.40 <| fs / f34 | <0.85. 9. The focal length of the entire system at the wide-angle end is fw,
The distance from the last lens surface to the imaging surface in air is B
The zoom lens according to any one of claims 1 to 8, wherein, when F is satisfied, the relationship of 2.0 <BF / fw <5.0 is satisfied. 10. The focal length of the entire system at the wide-angle end is represented by f
w, the focal length of the ith lens group is fi (i = 1 to 5),
Assuming that the lens group, the fourth lens group, and the combined focal length are f34, 5.0 <f1 / fw <8.0 0.5 <| f2 | / fw <1.6 4.0 <f34 / fw <9. The zoom lens according to any one of claims 1 to 9, which satisfies a relationship of 5 2.0 <f5 / fw <5.0. 11. When the amount of movement of the correction lens at the focal length f of the entire system at the time of camera shake correction is Y, the amount of movement of the correction lens at the telephoto end is Yt, and the focal length at the telephoto end is ft, Yt> Y (Y The zoom lens according to any one of claims 1 to 10, which satisfies the following relationship: /Yt)/(f/ft)<1.5. 12. A video camera using the zoom lens according to claim 1.