JP2011237832A - Zoom lens and imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance zoom lens or the like which is suitable for an electronic imaging element having a large number of pixels and achieves a high variable magnification ratio and miniaturization.SOLUTION: This zoom lens comprises a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, a third lens group G3 having a positive refractive power, a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power in the order from the object side along the optical axis. The variable magnification from a wide-angle end state W to a telephoto end state T is performed by moving the second lens group G2 and the fourth lens group G4 into the optical axis direction. The first lens group G1 comprises a front lens Group G1f having a negative refractive power, an optical path bending element P for bending the optical path, and a rear lens group G1r having a positive refractive power in the order from the object side along the optical axis, and satisfies a predetermined conditional expression.

Description

  The present invention relates to a zoom lens, an imaging apparatus, a zoom lens zooming method, and a zoom lens vibration isolation method.

  2. Description of the Related Art Conventionally, a camera that outputs a formed subject image as an electrical signal using a light receiving element such as an electronic image pickup device and records it as a digital image, such as an electronic still camera, is often used. In particular, in recent years, electronic imaging devices have been miniaturized and highly integrated, and inexpensive and high-pixel ones have been provided. Since miniaturization is also achieved by high integration, a lens system for a camera equipped with such an electronic image sensor is also miniaturized.

  However, when a zoom lens is used in the above-described camera, especially when trying to increase the zoom ratio, the number of lenses is considered in consideration of aberration correction of each lens group constituting the zoom lens. Increases, the thickness of each lens group increases, and the overall length of the lens increases. Therefore, although there is a limit to the miniaturization of the zoom lens and the camera, in recent years, the design and portability of the camera are emphasized, and the demand for further miniaturization has increased.

  Under such a background, a method for reducing the size by arranging an optical path bending element for bending an optical path in a zoom lens has been proposed. Specifically, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power; And a fourth lens group having a positive refractive power, and a zoom lens having a zoom ratio of about 3 has been proposed in which a prism for bending an optical path is disposed in the first lens group (for example, (See Patent Document 1).

JP 2000-131610 A

  Here, when an optical path bending element for bending the optical path is disposed in the zoom lens, in order to reduce the length of the zoom lens in the depth direction, that is, the length of the zoom lens in the incident optical axis direction, the optical path bending element It is most effective to arrange in the first lens group. In this case, it is possible to further reduce the length of the zoom lens in the depth direction by reducing the size of the optical path bending element itself.

  However, when the zoom lens has a high zoom ratio, the total optical length necessary for zooming increases, so the lens diameter of the first lens group must be increased. Therefore, along with this, the optical path bending element must also be enlarged, and the length of the zoom lens in the depth direction cannot be shortened.

  In the conventional zoom lens, the length in the depth direction is shortened by arranging the prism for bending the optical path in the first lens group as described above. However, the zoom ratio is small, and There is a problem that miniaturization is not sufficiently achieved.

  Therefore, the present invention has been made in view of the above problems, and is suitable for a high-pixel electronic image pickup device, and is a high-performance zoom lens, an image pickup apparatus, and a zoom lens that achieve a high zoom ratio and a small size. An object of the present invention is to provide a magnification method and a vibration isolation method for a zoom lens.

In order to solve the above problems, the present invention
A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes, in order from the object side along the optical axis, a front lens group having negative refractive power, an optical path bending element for bending the optical path, and a rear lens group having positive refractive power. Have
Provided is a zoom lens characterized by satisfying the following conditional expressions (1) and (2).
(1) 0.3 <f1 / ft <0.6
(2) 0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group

The present invention also provides
A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes an optical path bending element for bending the optical path,
There is provided a zoom lens characterized in that the displacement of the imaging position due to blurring is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.

  Also provided is an imaging apparatus comprising the zoom lens of the present invention.

The present invention also provides
A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. A zoom lens zooming method having a fourth lens group having a negative refractive power and a fifth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes, in order from the object side along the optical axis, a front lens group having negative refractive power, an optical path bending element for bending the optical path, and a rear lens group having positive refractive power. Have
A zoom lens zooming method characterized by satisfying the following conditional expressions (1) and (2) is provided.
(1) 0.3 <f1 / ft <0.6
(2) 0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group

The present invention also provides
A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. An anti-vibration method for a zoom lens having a fourth lens group having a fifth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes an optical path bending element for bending the optical path,
A zoom lens image stabilization method is provided, wherein the displacement of the imaging position due to blurring is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.

  According to the present invention, a high-performance zoom lens, an image pickup apparatus, a zoom lens zoom method, and a zoom lens image stabilization method that are suitable for an electronic image sensor with a high pixel and have a high zoom ratio and a small size. Can be provided.

It is a figure which shows the cross section and zoom orbit of the zoom lens which concerns on 1st Example of this invention. (A), (b), and (c) are various aberrations during non-vibration prevention during focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 1. FIG. (A), (b), and (c) are lateral aberration diagrams during image stabilization when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state, respectively, of the zoom lens according to the first example. It is. It is a figure which shows the cross section and zoom track | orbit of a zoom lens which concern on 2nd Example of this invention. (A), (b), and (c) are various aberrations during non-vibration prevention when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 2. FIG. (A), (b), and (c) are lateral aberration diagrams during image stabilization when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 2, respectively. It is. It is a figure which shows the cross section and zoom orbit of the zoom lens which concerns on 3rd Example of this invention. (A), (b), and (c) are various aberrations during non-vibration prevention when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 3. FIG. (A), (b), and (c) are lateral aberration diagrams during image stabilization when focusing on an object at infinity in the wide-angle end state, intermediate focal length state, and telephoto end state of the zoom lens according to Example 3, respectively. It is. It is the front view (a) and back view (b) of a camera provided with this zoom lens. It is sectional drawing along the A-A 'line of Fig.10 (a).

Hereinafter, a zoom lens, an imaging apparatus, a zoom lens zooming method, and a zoom lens image stabilization method according to embodiments of the present invention will be described.
The zoom lens includes, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. A fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power, and zooming from the wide-angle end state to the telephoto end state is performed by the second lens group and the fourth lens group. The first lens group includes a front lens group having a negative refractive power in order from the object side along the optical axis, and an optical path for bending the optical path by approximately 90 °. It has a bending element and a rear lens group having a positive refractive power, and is configured to satisfy the following conditional expressions (1) and (2).
(1) 0.3 <f1 / ft <0.6
(2) 0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group

To increase the zoom ratio of a zoom lens, it is effective to increase the number of lens groups and the amount of movement of each lens group. However, this increases the size of the lens and the number of lenses. For this reason, a camera equipped with such a zoom lens becomes large even when the lens is housed in the camera body, that is, a so-called retracted state, and the camera body is enlarged.
Therefore, in this zoom lens, by arranging the optical path bending element in the first lens group as described above, the length of the zoom lens in the depth direction is shortened, and the lens barrel and the camera body are thinned. ing.

  Further, in order to further reduce the thickness of the lens barrel and the camera body, it is necessary to reduce the size of the optical path bending element. In this zoom lens, since the fifth lens group has a negative refractive power, the focal length of the entire lens group located closer to the object side than the fifth lens group is reduced, and the effective lens diameter is reduced. Therefore, the optical path bending element can be downsized.

In this zoom lens, the conditional expression (1) defines the relationship between the focal length of the first lens unit and the focal length of the entire zoom lens system in the telephoto end state.
If the lower limit value of conditional expression (1) is not reached, the refractive power of the first lens group will increase, and spherical aberration in the telephoto end state and chromatic aberration over the entire zoom range will deteriorate.
In order to secure the effect of the present invention, it is desirable to set the lower limit value of conditional expression (1) to 0.35.

On the other hand, if the upper limit value of conditional expression (1) is exceeded, the refractive power of the first lens group becomes small. Therefore, in order to realize a high zoom ratio, it is necessary to ensure a large amount of movement of the lens unit at the time of zooming, and thus the total length of the zoom lens becomes large. Alternatively, the refractive power of the third lens group and the fourth lens group must be increased, and astigmatism is deteriorated in the wide-angle end state.
As described above, when the zoom lens satisfies the conditional expression (1), it is possible to achieve a reduction in size while achieving a high zoom ratio.

Conditional expression (2) defines the focal length of the front lens group in the first lens group.
If the lower limit value of conditional expression (2) is not reached, that is, if the refractive power of the front lens unit is reduced, the effective diameter of the maximum field angle ray incident on the optical path bending element in the wide-angle end state cannot be reduced. For this reason, in order to bend the optical path over the entire angle of view, the optical path bending element must be enlarged, and it becomes impossible to achieve miniaturization. Alternatively, in order to reduce the size of the optical path bending element, it is necessary to increase the refractive power of the second lens unit to shorten the entire length of the zoom lens, and astigmatism in the wide-angle end state and axial chromatic aberration in the telephoto end state are caused. It will get worse.
In order to secure the effect of the present invention, it is desirable to set the lower limit value of conditional expression (2) to 0.80.

On the other hand, when the upper limit value of conditional expression (2) is exceeded, that is, when the refractive power of the front lens unit increases, spherical aberration in the telephoto end state deteriorates.
In order to secure the effect of the present invention, it is desirable to set the upper limit value of conditional expression (2) to 0.92.
As described above, when the present zoom lens satisfies the conditional expression (2), the optical path bending element can be reduced in size while favorably correcting various aberrations, and the zoom lens can be reduced in size.

In the zoom lens, it is desirable that the first lens group, the third lens group, and the fifth lens group are fixed with respect to the image plane during zooming from the wide-angle end state to the telephoto end state. .
With this configuration, since only two lens groups move, the drive system for driving these lens groups can be simplified. Therefore, it is possible to reduce the size of the lens barrel and save power.

In the zoom lens, it is preferable that focusing from an object at infinity to an object at a finite distance is performed by moving the fourth lens group in the optical axis direction.
With this configuration, since only two lens groups move, the drive system for driving these lens groups can be simplified. Therefore, it is possible to reduce the size of the lens barrel and save power.

In addition, it is desirable that the zoom lens satisfies the following conditional expression (3).
(3) 1.0 <βT5 <1.5
However,
βT5: imaging magnification of the fifth lens group at the time of focusing on an object at infinity in the telephoto end state

Conditional expression (3) defines the imaging magnification of the fifth lens group.
If the lower limit value of conditional expression (3) is not reached, the focal length of the entire lens unit located closer to the object side than the fifth lens unit becomes larger than the focal length of the entire zoom lens system. For this reason, the optical path bending element is increased in size and the zoom lens cannot be reduced in size.

On the other hand, if the upper limit of conditional expression (3) is exceeded, various aberrations, particularly spherical aberration in the telephoto end state, will become large.
In order to secure the effect of the present invention, it is desirable to set the upper limit of conditional expression (3) to 1.4.
As described above, when this zoom lens satisfies the conditional expression (3), it is possible to reduce the size of the zoom lens while satisfactorily correcting various aberrations such as spherical aberration.

In the zoom lens, it is preferable that the fifth lens group includes a single cemented lens.
With this configuration, the occurrence of chromatic aberration in the fifth lens group can be suppressed, and the relative eccentricity of the lens due to manufacturing errors can be made extremely small. The cemented lens may be a cemented lens including three or more lenses.

  In the zoom lens, it is preferable that the displacement of the imaging position due to the shake is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.

In general, an image stabilization method that corrects the displacement of the imaging position due to camera shake or the like by decentering a part of a lens system is required to have a small amount of decentering and extremely small performance degradation at the time of decentering. In particular, when the zoom lens is to be miniaturized by bending the optical path, it is essential to reduce the eccentricity. Further, the lens group to be decentered, that is, the anti-vibration lens group, is required to have a small diameter and to correct chromatic aberration and spherical aberration.
Therefore, this zoom lens has a configuration in which the third lens unit performs image stabilization as described above, so that each aberration can be corrected satisfactorily while setting the decentration sensitivity to an appropriate value. The performance degradation during shaking can be reduced.

  The zoom lens includes, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. A fourth lens group having a positive refractive power and a fifth lens group having a negative refractive power, and zooming from the wide-angle end state to the telephoto end state is performed by the second lens group and the fourth lens group. The first lens group has an optical path bending element for folding the optical path, and the third lens group is moved in a direction substantially perpendicular to the optical axis. Thus, the displacement of the imaging position due to the shake is corrected.

Here, in order to reduce the size of the optical system, it is an effective means to reduce the size of the image sensor used in combination with the optical system. However, if the imaging device is reduced in size, the light receiving element is miniaturized, and the amount of light received by each light receiving element is reduced, that is, the sensitivity is lowered. Note that even when the number of pixels of the image sensor is increased, the light receiving element is miniaturized, and similarly the sensitivity is lowered. Therefore, in order to compensate for the sensitivity reduction, it is necessary to increase the diameter of the optical system or to increase the exposure time during photographing. However, if the diameter of the optical system is increased, the size of the optical system increases and the effect of downsizing the imaging device is negated, which is contrary to the intention of the present invention. Further, if the exposure time is lengthened, camera shake is likely to occur, and thus an anti-vibration mechanism for correcting camera shake is required for the optical system.
Therefore, this zoom lens is configured to perform image stabilization by moving the third lens group in a direction substantially perpendicular to the optical axis as described above.

In general, an image stabilization method that corrects the displacement of the imaging position due to camera shake or the like by decentering a part of a lens system is required to have a small amount of decentering and extremely small performance degradation at the time of decentering. In particular, when the zoom lens is to be miniaturized by bending the optical path, it is essential to reduce the eccentricity. Further, the lens group to be decentered, that is, the anti-vibration lens group, is required to have a small diameter and to correct chromatic aberration and spherical aberration.
Therefore, this zoom lens has a configuration in which the third lens unit performs image stabilization as described above, so that each aberration can be corrected satisfactorily while setting the decentration sensitivity to an appropriate value. The performance degradation during shaking can be reduced.

In addition, it is desirable that the zoom lens satisfies the following conditional expression (4).
(4) 1.0 <(1-β3T) · βrT <1.8
However,
β3T: Imaging magnification of the third lens group at the time of focusing on an object at infinity in the telephoto end state βrT: Composite imaging magnification of the lens groups positioned on the image side of the third lens group

Conditional expression (4) defines the relationship between the imaging magnification of the third lens group and the imaging magnification of the entire lens group located on the image side of the third lens group. Represents core sensitivity.
If the lower limit value of conditional expression (4) is not reached, the amount of decentering of the third lens group for correcting blur increases. Therefore, the vibration isolation mechanism becomes large, and the lens barrel cannot be thinned. Further, if it is attempted to reduce the thickness of the lens barrel as it is, it is impossible to correct a large blur. For this reason, a sufficient blur correction effect due to image stabilization cannot be obtained, coma aberration is deteriorated, and good imaging performance cannot be achieved.
In order to secure the effect of the present invention, it is desirable to set the lower limit of conditional expression (4) to 1.05.

On the other hand, if the upper limit value of conditional expression (4) is exceeded, the decentering sensitivity of the third lens group becomes too high. For this reason, the displacement of the image occurs due to a minute control error, leading to a decrease in contrast.
In order to secure the effect of the present invention, it is desirable to set the upper limit of conditional expression (4) to 1.65. And in order to make the effect of this invention the most reliable, it is desirable to set the upper limit of conditional expression (4) to 1.50.
As described above, when this zoom lens satisfies the conditional expression (4), it is possible to realize a sufficient blur correction effect while being small.

In addition, it is desirable that this zoom lens satisfies the following conditional expression (5).
(5) -0.2 <1 / β3T <0.2
However,
β3T: Imaging magnification of the third lens group when focusing on an object at infinity in the telephoto end state

Conditional expression (5) defines the imaging magnification of the third lens group.
If the lower limit of conditional expression (5) is not reached, the refractive power of the third lens group becomes large, which is advantageous for shortening the optical total length. However, since the astigmatism increases due to the decentering of the third lens group with the fourth lens group, the optical performance during the image stabilization is greatly deteriorated.

On the other hand, if the upper limit value of conditional expression (5) is exceeded, the optical total length becomes large. Further, in order to reduce this optical total length, the refractive power of the first lens group and the fourth lens group must be increased, which makes it difficult to correct spherical aberration. Similarly, since the astigmatism increases due to the decentering of the third lens group with the fourth lens group, the optical performance during the image stabilization is greatly deteriorated.
In order to secure the effect of the present invention, it is desirable to set the upper limit of conditional expression (5) to 0.1.
As described above, this zoom lens satisfies the conditional expression (5), thereby preventing deterioration of the optical performance when the third lens group is decentered from the fourth lens group, and achieving high optical performance even during image stabilization. be able to.

In the zoom lens, the first lens group includes, in order from the object side along the optical axis, a front lens group having a negative refractive power, the optical path bending element, and a rear lens group having a positive refractive power. It is desirable that the following conditional expressions (1) and (2) are satisfied.
(1) 0.3 <f1 / ft <0.6
(2) 0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group Since conditional expression (1) and conditional expression (2) are the same as those described above, the description thereof is omitted.

In the zoom lens, it is desirable that the first lens group, the third lens group, and the fifth lens group are fixed with respect to the image plane during zooming from the wide-angle end state to the telephoto end state. .
With this configuration, since only two lens groups move, the drive system for driving these lens groups can be simplified. Therefore, it is possible to reduce the size of the lens barrel and save power.

In the zoom lens, it is preferable that focusing from an object at infinity to an object at a finite distance is performed by moving the fourth lens group in the optical axis direction.
With this configuration, since only two lens groups move, the drive system for driving these lens groups can be simplified. Therefore, it is possible to reduce the size of the lens barrel and save power.

In addition, it is desirable that the zoom lens satisfies the following conditional expression (3).
(3) 1.0 <βT5 <1.5
However,
βT5: Imaging magnification of the fifth lens group at the time of focusing on an object at infinity in the telephoto end state Note that since this conditional expression (3) is the same as that described above, its description is omitted.

In the zoom lens, it is preferable that the fifth lens group includes a single cemented lens.
With this configuration, the occurrence of chromatic aberration in the fifth lens group can be suppressed, and the relative eccentricity of the lens due to manufacturing errors can be made extremely small. The cemented lens may be a cemented lens including three or more lenses.

This imaging apparatus includes the zoom lens having the above-described configuration.
As a result, it is possible to realize a high-performance imaging device that is suitable for a high-pixel electronic imaging device and has a high zoom ratio and a small size.

The zoom lens zooming method includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a first lens having a positive refractive power in order from the object side along the optical axis. A zooming method of a zoom lens having three lens groups, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power, and changing from a wide-angle end state to a telephoto end state The magnification is performed by moving the second lens group and the fourth lens group in the optical axis direction. The first lens group has a negative refractive power in order from the object side along the optical axis. A group, an optical path bending element for bending the optical path, and a rear lens group having a positive refractive power, satisfy the following conditional expressions (1) and (2).
(1) 0.3 <f1 / ft <0.6
(2) 0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: Focal length of the first lens group fw: Focal length of the zoom lens in the wide-angle end state ft: Focal length of the zoom lens in the telephoto end state fn1: Focal length of the front lens group in the first lens group Accordingly, it is possible to realize a high-performance zoom lens suitable for a high-pixel electronic image pickup device and having a high zoom ratio and a small size.

The anti-vibration method of the zoom lens includes, in order from the object side along the optical axis, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a first lens group having a positive refractive power. A zoom lens anti-vibration method having three lens groups, a fourth lens group having a positive refractive power, and a fifth lens group having a negative refractive power, which changes from a wide-angle end state to a telephoto end state. The magnification is performed by moving the second lens group and the fourth lens group in the optical axis direction. The first lens group includes an optical path bending element for bending an optical path, and the third lens group is It is characterized in that the displacement of the imaging position due to the shake is corrected by moving in a direction substantially perpendicular to the optical axis.
As a result, it is possible to realize a high-performance zoom lens suitable for a high-pixel electronic image pickup device and having a high zoom ratio and a small size.

Hereinafter, a variable magnification optical system according to numerical examples will be described with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a diagram showing a cross section and a zoom trajectory of a zoom lens according to the first embodiment of the present invention.
The zoom lens according to the present example has, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. The third lens group G3 includes a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power.

The first lens group G1 includes, in order from the object side along the optical axis, a front lens group G1f having a negative refractive power, a right-angle prism P for bending the optical path, and a rear lens group G1r having a positive refractive power. It consists of and.
The front lens group G1f includes a negative meniscus lens L11 having a concave surface directed toward the image side. The rear lens group G1r includes a biconvex positive lens L12 and a biconvex positive lens L13 having an aspheric lens surface on the object side in order from the object side along the optical axis.
Note that the zoom lens according to the present embodiment has a configuration in which the optical path is bent by about 90 ° by the right-angle prism P, but is shown in an expanded manner in FIG.

The second lens group G2 includes, in order from the object side along the optical axis, a biconcave negative lens L21 having an aspheric lens surface on the image side, a biconcave negative lens L22, and a biconvex positive lens. It consists of a cemented lens with L23.
The third lens group G3 includes, in order from the object side along the optical axis, a biconvex positive lens L31 having an aspheric lens surface on the image side, a biconvex positive lens L32, and a biconcave negative lens. It consists of a cemented lens with L33.

The fourth lens group G4 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L41 having a concave surface directed to the image side and a biconvex positive lens L42 having an aspheric lens surface on the image side. It consists of
The fifth lens group G5 includes, in order from the object side along the optical axis, a cemented lens of a biconvex positive lens L51 and a biconcave negative lens L52.
In addition, an aperture stop S is provided on the object side of the third lens group G3, and a spatial frequency higher than the limit resolution of an image sensor (not shown) is cut between the fifth lens group G5 and the image plane I. A low pass filter FL is provided.

In the zoom lens according to the present embodiment having such a configuration, the distance between the first lens group G1 and the second lens group G2 increases upon zooming from the wide-angle end state to the telephoto end state, and the second lens group G2 The second lens group G2 moves to the image side so that the distance between the third lens group G3 decreases and the distance between the third lens group G3 and the fourth lens group G4 changes. The first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I after moving toward the object side and then toward the image side.
In the zoom lens according to the present embodiment, the entire third lens group G3 is moved in a direction substantially perpendicular to the optical axis, thereby correcting the displacement of the imaging position due to the shake.

Table 1 below lists values of specifications of the zoom lens according to the first example.
In [Overall Specifications], f represents a focal length, FNO represents an F number, and ω represents a half angle of view (maximum incident angle, unit is “°”).
In [Lens data], the first column N is the order of the lens surfaces counted from the object side, the second column R is the radius of curvature of the lens surfaces, the third column D is the distance between the lens surfaces, and the fourth column nd is the d line ( The refractive index for the wavelength λ = 587.6 nm), the fifth column νd indicates the Abbe number for the d-line (wavelength λ = 587.6 nm). Note that the radius of curvature ∞ indicates a plane, and the refractive index of air nd = 1.0000 is omitted.

[Aspherical data] shows the aspherical coefficient when the shape of the aspherical surface is expressed by the following equation.
x = cy ² / {1+ (1-κc ² y ² ) ^1/2 } + C4y ⁴ + C6y ⁶ +...
Here, y is the height from the optical axis, x is the sag amount (displacement in the optical axis direction at the position of the height y from the optical axis when the apex of the aspheric surface is used as a reference), and c is the reference spherical surface. The curvature (paraxial curvature), κ is the conic constant, and C4, C6. “En” indicates “× 10 ⁻ⁿ ”, for example “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”.
[Variable interval data] indicates the focal length f and the variable interval between the lens groups.

  It should be noted that “mm” is generally used as a unit for the focal length f, the radius of curvature r, and other lengths listed in all the specification values of the following embodiments. However, since the optical system can obtain the same optical performance even when proportionally enlarged or reduced, the unit is not limited to “mm”. Note that the same reference numerals as in the present embodiment are used in the specification values of the following embodiments.

(Table 1)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 6.50 to 15.00 to 30.60
FNO = 3.74 to 4.15 to 5.04
ω = 31.7 to 13.7 to 6.7

[Lens data]
N R D nd νd
1 50.0000 1.0000 1.846660 23.78
2 10.9000 2.1000
3 ∞ 10.5000 1.804000 46.57
4 ∞ 0.2000
5 18.9550 2.6000 1.497820 82.56
6 -16.8287 0.1000
7 24.7775 1.8000 1.743300 49.32
8 -616.4597 (D8)

9 -20.9803 0.9000 1.820800 42.71
10 8.7929 1.0000
11 -10.4372 0.9000 1.816000 46.62
12 7.3865 1.8000 1.846660 23.78
13 -27.8034 (D13)

14 ∞ 0.2000 (Aperture stop S)
15 10.5499 2.2000 1.589129 61.25
16 -18.3608 0.3000
17 8.7286 3.4000 1.497820 82.56
18 -9.0124 0.9000 1.785896 44.20
19 8.5239 (D19)

20 9.3388 0.9000 1.785896 44.20
21 5.7878 2.6000 1.497820 82.56
22 -16.8053 (D22)

23 72.2380 2.3000 1.516330 64.14
24 -7.1765 0.9000 1.755199 27.51
25 227.3969 4.3900
26 ∞ 1.6500 1.544370 70.51
27 ∞

[Aspherical data]
7th surface κ = -7.6507
C4 = 4.88800E-05
C6 = -5.48520E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00
10th surface κ = 6.8403
C4 = -1.37810E-03
C6 = -7.98430E-06
C8 = -9.52370E-06
C10 = 0.00000E + 00
16th surface κ = -11.6168
C4 = -1.39880E-04
C6 = 1.77700E-06
C8 = 0.00000E + 00
C10 = 0.00000E + 00
22nd surface κ = -10.1342
C4 = -1.71540E-04
C6 = -6.06960E-07
C8 = 0.00000E + 00
C10 = 0.00000E + 00

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state f 6.5000 15.0000 30.6000
D8 1.0357 6.6328 10.9658
D13 11.4002 5.8030 1.4700
D19 6.6537 2.6818 4.2525
D22 3.8073 7.7792 6.2085

[Values for conditional expressions]
(1) f1 / ft = 0.46
(2) (fw · ft) ^1/2 /|fb1|=0.85
(3) βT5 = 1.19
(4) (1-β3T) · βrT = 1.30
(5) 1 / β3T = -0.03

FIGS. 2A and 3A are graphs showing various aberrations during non-vibration prevention when an object at infinity is in focus at the wide-angle end state (f = 6.50) of the zoom lens according to the first example. FIG. 6 is a lateral aberration diagram during vibration isolation (θ = 0.8).
FIGS. 2B and 3B respectively show various aberrations during non-vibration prevention when focusing on an object at infinity in the intermediate focal length state (f = 15.0) of the zoom lens according to the first example. FIG. 6 is a lateral aberration diagram at the time of image stabilization (θ = 0.6).
FIGS. 2C and 3C are graphs showing various aberrations at the time of non-vibration prevention when focusing on an object at infinity in the telephoto end state (f = 30.6) of the zoom lens according to the first example. FIG. 6 is a lateral aberration diagram during vibration isolation (θ = 0.5).

In each aberration diagram, FNO represents an F number, and Y represents an image height. The spherical aberration diagram shows the F-number value corresponding to the maximum aperture, the astigmatism diagram and the distortion diagram show the maximum image height, and the coma diagram shows the value of each image height. Further, d represents the aberration at the d-line (λ = 587.6 nm), and g represents the aberration at the g-line (λ = 435.8 nm). In the astigmatism diagram, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. Furthermore, θ is a correction angle (unit: “°”) during image stabilization.
In addition, in the various aberration diagrams of each example shown below, the same reference numerals as those in this example are used.

  From the various aberration diagrams, it can be seen that the zoom lens according to the present embodiment corrects various aberrations well from the wide-angle end state to the telephoto end state and has excellent optical performance.

(Second embodiment)
FIG. 4 is a diagram showing a cross section and a zoom trajectory of the zoom lens according to the second embodiment of the present invention.
The zoom lens according to the present example has, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. The third lens group G3 includes a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power.

The first lens group G1 includes, in order from the object side along the optical axis, a front lens group G1f having a negative refractive power, a right-angle prism P for bending the optical path, and a rear lens group G1r having a positive refractive power. It consists of and.
The front lens group G1f includes a negative meniscus lens L11 having a concave surface directed toward the image side. The rear lens group G1r is composed of a biconvex positive lens L12 and a biconvex positive lens L13 having both aspherical lens surfaces in order from the object side along the optical axis.
Note that the zoom lens according to the present embodiment has a configuration in which the optical path is bent by about 90 ° by the right-angle prism P, but is shown in an expanded manner in FIG.

The second lens group G2 includes, in order from the object side along the optical axis, a negative meniscus lens L21 having a concave surface directed toward the image side, and a cemented lens of a biconcave negative lens L22 and a biconvex positive lens L23. It is composed of
The third lens group G3 includes, in order from the object side along the optical axis, a biconvex positive lens L31 having an aspheric lens surface on the image side, a biconvex positive lens L32, and a biconcave negative lens. It consists of a cemented lens with L33.

The fourth lens group G4 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L41 having a concave surface directed to the image side and a biconvex positive lens L42 having an aspheric lens surface on the image side. It consists of
The fifth lens group G5 includes, in order from the object side along the optical axis, a cemented lens of a biconcave negative lens L51 and a biconvex positive lens L52.
In addition, an aperture stop S is provided on the object side of the third lens group G3, and a spatial frequency higher than the limit resolution of an image sensor (not shown) is cut between the fifth lens group G5 and the image plane I. A low pass filter FL is provided.

In the zoom lens according to the present embodiment having such a configuration, the distance between the first lens group G1 and the second lens group G2 increases upon zooming from the wide-angle end state to the telephoto end state, and the second lens group G2 The second lens group G2 moves to the image side so that the distance between the third lens group G3 decreases and the distance between the third lens group G3 and the fourth lens group G4 changes. The first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I after moving toward the object side and then toward the image side.
In the zoom lens according to the present embodiment, the entire third lens group G3 is moved in a direction substantially perpendicular to the optical axis, thereby correcting the displacement of the imaging position due to the shake.
Table 2 below provides values of specifications of the zoom lens according to the second example.

(Table 2)
[Overall specifications]
Wide angle end state Intermediate focal length state Telephoto end state f = 6.50 to 15.00 to 30.40
FNO = 3.79 to 4.15 to 5.04
ω = 31.5-13.6-6.7

[Lens data]
N R D nd νd
1 58.7063 1.0000 1.846660 23.78
2 10.9555 2.2000
3 ∞ 10.5000 1.804000 46.57
4 ∞ 0.2000
5 30.0095 2.6000 1.497820 82.56
6 -17.9811 0.1000
7 32.6887 1.8000 1.743300 49.32
8 -61.7001 (D8)

9 65.6074 0.9000 1.754999 52.32
10 8.6545 1.0000
11 -8.5010 0.9000 1.816000 46.62
12 10.1254 1.6046 1.846660 23.78
13 -30.5218 (D13)

14 ∞ 0.2000 (Aperture stop S)
15 8.7161 2.2000 1.589130 61.24
16 -24.0449 0.1000
17 8.5006 3.5000 1.497820 82.56
18 -7.2314 0.9000 1.785896 44.20
19 7.2248 (D19)

20 10.4319 0.9000 1.785896 44.20
21 7.6858 2.2000 1.497820 82.56
22 -14.3042 (D22)

23 -38.9384 0.9000 1.755199 27.51
24 8.2117 2.3000 1.516330 64.14
25 -25.0350 2.8600
26 ∞ 1.6500 1.544370 70.51
27 ∞

[Aspherical data]
7th surface κ = 6.2256
C4 = -1.25520E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = -3.30180E-10
8th surface κ = 5.0851
C4 = -1.23980E-04
C6 = 9.31640E-07
C8 = -2.28530E-08
C10 = 0.00000E + 00
16th surface κ = -22.1815
C4 = -1.04460E-04
C6 = 0.00000E + 00
C8 = 0.00000E + 00
C10 = 0.00000E + 00
22nd surface κ = 12.2318
C4 = 7.50160E-04
C6 = 3.76350E-05
C8 = -2.50090E-06
C10 = 2.04040E-07

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state f 6.5000 15.0000 30.4000
D8 1.1077 8.1330 13.5434
D13 13.9645 6.9393 1.5289
D19 5.4092 2.3834 4.2622
D22 3.7129 6.7387 4.8599

[Values for conditional expressions]
(1) f1 / ft = 0.55
(2) (fw · ft) ^1/2 /|fb1|=0.88
(3) βT5 = 1.24
(4) (1-β3T) · βrT = 1.12
(5) 1 / β3T = -0.16

FIGS. 5A and 6A are graphs showing various aberrations during non-vibration prevention when an object at infinity is in focus at the wide-angle end state (f = 6.50) of the zoom lens according to the second example. FIG. 6 is a lateral aberration diagram during vibration isolation (θ = 0.8).
FIGS. 5B and 6B respectively show various aberrations during non-vibration prevention when an object at infinity is in focus in the intermediate focal length state (f = 15.0) of the zoom lens according to the second example. FIG. 6 is a lateral aberration diagram at the time of image stabilization (θ = 0.6).
FIGS. 5 (c) and 6 (c) are graphs showing various aberrations during non-vibration prevention when focusing on an object at infinity in the telephoto end state (f = 30.4) of the zoom lens according to the second example. FIG. 6 is a lateral aberration diagram during vibration isolation (θ = 0.5).

  From the various aberration diagrams, it can be seen that the zoom lens according to the present embodiment corrects various aberrations well from the wide-angle end state to the telephoto end state and has excellent optical performance.

(Third embodiment)
FIG. 7 is a diagram showing a cross section and a zoom trajectory of the zoom lens according to the third embodiment of the present invention.
The zoom lens according to the present example has, in order from the object side along the optical axis, a first lens group G1 having a positive refractive power, a second lens group G2 having a negative refractive power, and a positive refractive power. The third lens group G3 includes a fourth lens group G4 having a positive refractive power, and a fifth lens group G5 having a negative refractive power.

The first lens group G1 includes, in order from the object side along the optical axis, a front lens group G1f having a negative refractive power, a right-angle prism P for bending the optical path, and a rear lens group G1r having a positive refractive power. It consists of and.
The front lens group G1f includes a negative meniscus lens L11 having a concave surface directed toward the image side. The rear lens group G1r includes, in order from the object side along the optical axis, a biconvex positive lens L12 having an aspheric lens surface on the image side and a biconvex positive lens L13.
Note that the zoom lens according to the present embodiment has a configuration in which the optical path is bent by about 90 ° by the right-angle prism P, but is shown in an expanded manner in FIG.

The second lens group G2 includes, in order from the object side along the optical axis, a biconcave negative lens L21 having an aspheric lens surface on the image side, a biconcave negative lens L22, and a biconvex positive lens. It consists of a cemented lens with L23.
The third lens group G3 includes, in order from the object side along the optical axis, a biconvex positive lens L31 having an aspheric lens surface on the image side, a biconvex positive lens L32, and a biconcave negative lens. It consists of a cemented lens with L33.

The fourth lens group G4 includes, in order from the object side along the optical axis, a cemented lens of a negative meniscus lens L41 having a concave surface directed to the image side and a biconvex positive lens L42 having an aspheric lens surface on the image side. It consists of
The fifth lens group G5 includes, in order from the object side along the optical axis, a cemented lens of a positive meniscus lens L51 having a convex surface facing the image side and a negative meniscus lens L52 having a concave surface facing the object side.
In addition, an aperture stop S is provided on the object side of the third lens group G3, and a spatial frequency higher than the limit resolution of an image sensor (not shown) is cut between the fifth lens group G5 and the image plane I. A low pass filter FL is provided.

In the zoom lens according to the present embodiment having such a configuration, the distance between the first lens group G1 and the second lens group G2 increases upon zooming from the wide-angle end state to the telephoto end state, and the second lens group G2 The second lens group G2 moves to the image side so that the distance between the third lens group G3 decreases and the distance between the third lens group G3 and the fourth lens group G4 changes. The first lens group G1, the third lens group G3, and the fifth lens group G5 are fixed with respect to the image plane I after moving toward the object side and then toward the image side.
In the zoom lens according to the present embodiment, the entire third lens group G3 is moved in a direction substantially perpendicular to the optical axis, thereby correcting the displacement of the imaging position due to the shake.
Table 3 below lists values of specifications of the zoom lens according to the third example.

(Table 3)
[Overall specifications]
Wide-angle end state Intermediate focal length state Telephoto end state f = 6.50 to 15.00 to 30.60
FNO = 3.65 to 4.67 to 5.65
ω = 31.5-13.6-6.7

[Lens data]
N R D nd νd
1 50.0000 1.0000 1.846660 23.78
2 10.6981 2.1000
3 ∞ 10.5000 1.804000 46.57
4 ∞ 0.2000
5 63.4799 1.8000 1.816000 46.62
6 -45.5382 0.1000
7 20.0360 2.6000 1.497820 82.52
8 -16.4521 (D8)

9 -22.2518 0.9000 1.816000 46.62
10 9.0739 1.0000
11 -10.4412 0.9000 1.816000 46.62
12 9.3760 1.8000 1.846660 23.78
13 -25.5289 (D13)

14 ∞ 0.2000 (Aperture stop S)
15 8.4490 2.2000 1.589129 61.25
16 -20.8665 0.1000
17 8.1025 3.4000 1.497820 82.52
18 -6.4970 0.9000 1.743997 44.79
19 6.6331 (D19)

20 10.6344 0.9000 1.720467 34.71
21 7.1416 2.6000 1.497820 82.52
22 -19.2110 (D22)

23 -69.2138 3.5000 1.516330 64.14
24 -6.0271 0.9000 1.755199 27.51
25 -23.9599 3.3195
26 ∞ 1.6500 1.544370 70.51
27 ∞

[Aspherical data]
6th surface κ = 1.0329
C4 = 3.47900E-05
C6 = 2.25660E-07
C8 = -2.12820E-09
C10 = 6.31030E-11
10th surface κ = 2.5562
C4 = -4.97900E-04
C6 = 6.38510E-06
C8 = -1.59650E-06
C10 = 6.44070E-08
16th surface κ = -0.8998
C4 = 1.08270E-04
C6 = -1.42490E-06
C8 = -1.47810E-07
C10 = 4.36000E-09
22nd surface κ = 1.0000
C4 = 1.12160E-04
C6 = 3.82280E-06
C8 = -4.48830E-07
C10 = 1.40980E-08

[Variable interval data]
Wide-angle end state Intermediate focal length state Telephoto end state f 6.5000 15.0000 30.6000
D8 1.1945 6.9917 11.4976
D13 11.4032 5.6059 1.1001
D19 6.9585 2.1658 2.7858
D22 3.2125 8.0052 7.3851

[Values for conditional expressions]
(1) f1 / ft = 0.48
(2) (fw · ft) ^1/2 /|fb1|=0.87
(3) βT5 = 1.12
(4) (1-β3T) · βrT = 1.38
(5) 1 / β3T = 0.00

FIGS. 8A and 9A are graphs showing various aberrations during non-vibration prevention when an object at infinity is in focus at the wide-angle end state (f = 6.50) of the zoom lens according to the third example. FIG. 6 is a lateral aberration diagram during vibration isolation (θ = 0.8).
FIGS. 8B and 9B respectively show various aberrations during non-vibration prevention when focusing on an object at infinity in the intermediate focal length state (f = 15.0) of the zoom lens according to the third example. FIG. 6 is a lateral aberration diagram at the time of image stabilization (θ = 0.6).
FIGS. 8C and 9C are graphs showing various aberrations during non-vibration prevention when focusing on an object at infinity in the telephoto end state (f = 30.6) of the zoom lens according to the third example. FIG. 6 is a lateral aberration diagram during vibration isolation (θ = 0.5).

  From the various aberration diagrams, it can be seen that the zoom lens according to the present embodiment corrects various aberrations well from the wide-angle end state to the telephoto end state and has excellent optical performance.

According to each of the embodiments described above, it is possible to realize a high-performance zoom lens suitable for a high-pixel electronic image pickup device and having a high zoom ratio and a small size.
In addition, although the five-group configuration of the present zoom lens is shown as a numerical example, the group configuration of the present zoom lens is not limited to this, and a zoom lens having another group configuration such as the sixth group or the seventh group is configured. You can also.

  In addition, in this zoom lens, in order to focus from an object at infinity to an object at a short distance, a part of the lens group, one lens group, or a plurality of lens groups are moved in the optical axis direction as the focusing lens group. A configuration may be adopted. This focusing lens group can be applied to autofocus, and is also suitable for driving an autofocus motor, such as an ultrasonic motor. In the zoom lens, it is particularly preferable that the second lens group or the fourth lens group is a focusing lens group.

The lens surface of the lens constituting the zoom lens may be an aspherical surface. This aspherical surface may be any of an aspherical surface by grinding, a glass mold aspherical surface obtained by molding glass into an aspherical shape, or a composite aspherical surface in which a resin provided on the glass surface is formed into an aspherical shape.
Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the zoom lens. Thereby, flare and ghost can be reduced, and high optical performance can be achieved with high contrast.
In addition, each said Example has shown one specific example of this invention, and this invention is not limited to these.

Next, a camera equipped with this zoom lens will be described with reference to FIGS.
FIG. 10 is a front view (a) and a rear view (b) of a camera provided with the zoom lens. FIG. 11 is a cross-sectional view taken along the line AA ′ in FIG.
The camera 1 is an electronic still camera provided with the zoom lens according to the first embodiment as a photographic lens 2 as shown in FIGS.

  In the camera 1, when a power button (not shown) is pressed by the photographer, a shutter (not shown) that covers the taking lens 2 is opened. As a result, light from a subject (not shown) enters the photographing lens 2 and is deflected approximately 90 ° downward by the right-angle prism P in the photographing lens 2 as shown in FIG. It is illuminated and a subject image is formed. This subject image is captured by the image sensor C and displayed on the liquid crystal monitor 3 provided on the back surface of the camera 1. As a result, the photographer determines the composition of the subject image while looking at the liquid crystal monitor 3 and then presses the release button 4 so that the subject image is picked up by the image sensor C and recorded and stored in a memory (not shown). Become. In this way, the photographer can photograph the subject with the camera 1.

  The camera 1 includes an auxiliary light emitting unit 5 that emits auxiliary light when the shooting environment is dark, and a wide-teleswitch 6 for zooming the zoom lens as the shooting lens 2 from the wide-angle end state to the telephoto end state. And a function button 7 for setting various conditions of the camera 1 and the like.

Here, the zoom lens according to the first embodiment mounted on the camera 1 as the photographing lens 2 is suitable for a high-pixel electronic image sensor due to its characteristic lens configuration as described in the first embodiment. This is a high-performance zoom lens with a high zoom ratio and a small size. As a result, the camera 1 is suitable for a high-pixel electronic image sensor, and can achieve a high zoom ratio and a small size.
It should be noted that the same effects as those of the camera 1 can of course be achieved even if a camera in which the zoom lens according to the second and third embodiments is mounted as the photographing lens 2 is configured.

  As described above, it is possible to provide a zoom lens, an imaging apparatus, a zoom lens zooming method, and a zoom lens image stabilization method.

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G1f Front lens group G1r Rear lens group S Aperture stop FL Low pass filter I Image surface W Wide angle end state T Telephoto end Status

In order to solve the above problems, the present invention
A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes an optical path bending element for bending the optical path,
The third lens group includes a plurality of lenses;
There is provided a zoom lens characterized in that the displacement of the imaging position due to blurring is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.

Claims (17)

A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes, in order from the object side along the optical axis, a front lens group having negative refractive power, an optical path bending element for bending the optical path, and a rear lens group having positive refractive power. Have
A zoom lens satisfying the following conditional expression:
0.3 <f1 / ft <0.6
0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group   The first lens group, the third lens group, and the fifth lens group are fixed with respect to an image plane during zooming from the wide-angle end state to the telephoto end state. The described zoom lens.   The zoom lens according to claim 1 or 2, wherein focusing from an object at infinity to an object at a finite distance is performed by moving the fourth lens group in the optical axis direction. The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
1.0 <βT5 <1.5
However,
βT5: imaging magnification of the fifth lens group at the time of focusing on an object at infinity in the telephoto end state   The zoom lens according to any one of claims 1 to 4, wherein the fifth lens group includes a single cemented lens.   6. The displacement of the imaging position due to the shake is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis. 6. Zoom lens. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. And a fourth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes an optical path bending element for bending the optical path,
A zoom lens, wherein the displacement of the imaging position due to the blur is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis. The zoom lens according to claim 7, wherein the following conditional expression is satisfied.
1.0 <(1-β3T) · βrT <1.8
However,
β3T: Imaging magnification of the third lens group at the time of focusing on an object at infinity in the telephoto end state βrT: Composite imaging magnification of the lens groups positioned on the image side of the third lens group The zoom lens according to claim 8, wherein the following conditional expression is satisfied.
-0.2 <1 / β3T <0.2
However,
β3T: Imaging magnification of the third lens group when focusing on an object at infinity in the telephoto end state The first lens group includes, in order from the object side along the optical axis, a front lens group having a negative refractive power, the optical path bending element, and a rear lens group having a positive refractive power,
The zoom lens according to any one of claims 7 to 9, wherein the following conditional expression is satisfied.
0.3 <f1 / ft <0.6
0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group   The first lens group, the third lens group, and the fifth lens group are fixed with respect to an image plane during zooming from the wide-angle end state to the telephoto end state. The zoom lens according to claim 10.   The zoom lens according to any one of claims 7 to 11, wherein focusing from an object at infinity to an object at a finite distance is performed by moving the fourth lens group in an optical axis direction. . The zoom lens according to claim 7, wherein the following conditional expression is satisfied.
1.0 <βT5 <1.5
However,
βT5: imaging magnification of the fifth lens group at the time of focusing on an object at infinity in the telephoto end state   The zoom lens according to any one of claims 7 to 13, wherein the fifth lens group includes one cemented lens.   An image pickup apparatus comprising the zoom lens according to claim 1. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. A zoom lens zooming method having a fourth lens group having a negative refractive power and a fifth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes, in order from the object side along the optical axis, a front lens group having negative refractive power, an optical path bending element for bending the optical path, and a rear lens group having positive refractive power. Have
A zoom lens zooming method characterized by satisfying the following conditional expression:
0.3 <f1 / ft <0.6
0.75 <(fw · ft) ^1/2 /(−fn1)<0.95
However,
f1: focal length of the first lens group fw: focal length of the zoom lens in the wide-angle end state ft: focal length of the zoom lens in the telephoto end state fn1: focal length of the front lens group in the first lens group A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a positive refractive power in order from the object side along the optical axis. An anti-vibration method for a zoom lens having a fourth lens group having a fifth lens group having a negative refractive power,
The zooming from the wide-angle end state to the telephoto end state is performed by moving the second lens group and the fourth lens group in the optical axis direction,
The first lens group includes an optical path bending element for bending the optical path,
An image stabilization method for a zoom lens, wherein the displacement of the imaging position due to blurring is corrected by moving the third lens group in a direction substantially perpendicular to the optical axis.

Images