KR20140071864A - Zoom lens and image pickup apparatus including the same - Google Patents

Abstract

Disclosed is a zoom lens which can be small while maintaining excellent performance in zooming, focusing, or phase shift. The zoom lens includes a first lens group with negative refractive power; a second lens group with positive refractive power; a third lens group with the negative refractive power; and a fourth lens group with the positive refractive power from an object side in order. The first lens group and the fourth lens group are fixed in an optical axis direction when zooming from a wide-angle end to a telephoto end. The second lens group has a 2A lens group with the positive refractive power and a 2B lens group with the positive refractive power from the object side in order. A focusing function from a close object to an infinite object is provided by moving the 2B lens group in the optical axis direction. A phase can be shifted by shifting the third lens group in a direction perpendicular to an optical axis.

Description

[0001] The present invention relates to a zoom lens and an image pickup apparatus including the zoom lens.

The disclosed embodiments relate to a zoom lens and an imaging apparatus including the zoom lens, and more particularly to a zoom lens having a function of correcting a shake of a photographed image due to vibration. More specifically, the present invention relates to a zoom lens in which a first lens group and a fourth lens group are fixed with four lens groups of a first lens group to a fourth lens group, and at the time of magnification, will be.

(First lens group), a positive lens group (second lens group), a negative lens group (third lens group), and both groups (a fourth lens group), and the first lens group and the fourth lens group A zoom lens fixed to the bass is known (Patent Documents 1, 2 and 3).

Further, a zoom lens for correcting the shaking motion by the lens shift method in the above configuration is known (Patent Document 1). For example, in Patent Document 1, the upper side (image side) group of the second lens group is used as the camera shake correction group, and the third lens group is used as the focus group. In Patent Document 1, by adopting the above-described configuration, both the inner focus and the shake correction are achieved. However, in Patent Document 1, the configuration is such that the second lens group and the third lens group move far away from each other when the telephoto end is formed.

Here, when the zoom lens is actually used as a product, it is conceivable that the first lens group and the fourth lens group are fixed and the second lens group and the third lens group, which need to be moved, are configured as a unit. It is preferable to incorporate a VCM (voice coil motor) into the unit consisting of the second lens group and the third lens group and speed up the focusing operation by the VCM. However, in the configuration of Patent Document 1, since the second lens group and the third lens group are far away from each other when the telephoto end is used as described above, the configuration for incorporating VCM into the unit including the second lens group and the third lens group I can not adopt it.

Also, in Patent Document 1, the fourth lens group is composed of one lens, and if the last lens group is a single lens, it is difficult to secure performance.

In Patent Documents 2 and 3, although the inner focus is realized by using the third lens group as the focus group, there is no group that gives the image stabilization function.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2012-047813 Patent Document 2: Japanese Patent Application Laid-Open No. 2011-237737 Patent Document 3: Japanese Unexamined Patent Publication No. 2012-027262

A zoom lens having a function of correcting a shake of a photographed image due to vibration and an imaging apparatus including the zoom lens.

A zoom lens according to one type of the present invention comprises, in order from an object side, a first lens group having a negative refractive power; A second lens group having positive refractive power; A third lens group having negative refractive power; And a fourth lens group having positive refractive power. When the zoom lens is moved from the wide angle end to the telephoto end, the first lens group and the fourth lens group are fixed in the optical axis direction. Here, the second lens group includes, in order from the object side, a second A lens group having a positive refractive power and a second B lens group having a positive refractive power. By moving the second B lens group in the optical axis direction, The focusing function can be given to the first lens group. Further, the image can be shifted by shifting the third lens group in the direction perpendicular to the optical axis.

For example, the first lens group may include, in order from the object side, two negative lenses with the convex surface facing the object side and a positive lens with the convex surface facing the object side, Conditional expression:

0.3 <| f1 / ft | <1.0 (where f1 is the focal length of the first lens unit and ft is the focal length of the entire lens system at the telephoto end).

More preferably, the zoom lens satisfies the following conditional expression:

0.5 &lt; f1 / ft &lt; 0.8.

The second lens subunit may include at least one positive lens and at least one negative lens. The second lens subunit may include, in order from the object side, a negative lens And a positive lens, and the following conditional expression:

0.3 &lt; f2B / ft &lt; 1.0 and

0.3 &lt; f2A / ft &lt; 1.2, wherein f2A is a focal length of the second lens group having positive refractive power, which is formed on the object side of the second lens group, f2B is a quantity And ft is the focal length of the entire lens system at the telephoto end) can be satisfied.

More preferably, the zoom lens satisfies the following conditional expression:

0.5 &lt; f2B / ft &lt; 0.8 and

0.5 &lt; f2A / ft &lt; 0.9.

For example, the second A lens group may be composed of a positive lens with a convex surface facing the object side and a negative lens with a concave surface facing the image side.

For example, the negative lens and the positive lens of the second B lens group may be a cemented lens joined to each other.

The third lens group may include, in order from the object side, at least one positive lens and negative lens, and satisfies the following conditional expression:

0.3 <f3 / ft <1.2 (where f3 is the focal length of the third lens group, and ft is the focal length of the entire lens system at the telephoto end).

More preferably, the zoom lens satisfies the following conditional expression:

0.5 &lt; f3 / ft &lt; 0.9.

For example, the positive lens and the negative lens of the third lens group may be a cemented lens joined to each other.

For example, the positive lens of the third lens group may have a concave meniscus shape on the object side.

Further, the fourth lens group may include, in order from the object side, a positive lens and a negative lens, and the following conditional expression:

1.5 <f4 / ft (where f4 is the focal length of the fourth lens group, and ft is the focal length of the entire lens system at the telephoto end).

More preferably, the zoom lens satisfies the following conditional expression:

1.7 < f4 / ft &lt; 15.

For example, the positive lens and the negative lens of the fourth lens group may be a cemented lens joined to each other.

According to an embodiment, there is provided a zoom lens, comprising a first lens group and a second lens group, a second lens group, and a third lens group, The second lens group and the third lens group may move in the direction along the optical axis so that the interval between the lens groups and the interval between the third lens group and the fourth lens group are changed.

According to another aspect of the present invention, there is provided an image pickup apparatus comprising: a zoom lens having the above-described structure; And an imaging device that receives an optical image formed by the zoom lens and converts the received optical image into an electrical image signal.

According to another aspect of the present invention, there is provided a camera comprising a case capable of detachably attaching and detaching a zoom lens having the above-described structure as a replacement lens, wherein an optical image formed by the zoom lens is received in the case, So that the image pickup element to be converted can be received.

According to the disclosed embodiments, it is possible to realize a zoom lens capable of downsizing while maintaining good performance at the time of magnification change, focusing, and image shift.

1 is a cross-sectional view of a lens at a wide angle end of a lens according to one embodiment.
Fig. 2 is an aberration diagram at the wide-angle end of the lens shown in Fig.
Fig. 3 is an aberration diagram at the middle zoom position of the lens shown in Fig.
4 is an aberration diagram at the telephoto end of the lens shown in Fig.
5 is a cross-sectional view of a lens at a wide-angle end of a lens according to another embodiment.
6 is an aberration diagram at the wide-angle end of the lens shown in Fig.
7 is an aberration diagram at the middle zoom position of the lens shown in Fig.
8 is an aberration diagram at the telephoto end of the lens shown in Fig.
9 is a cross-sectional view of a lens at a wide-angle end of a lens according to another embodiment.
10 is an aberration diagram at the wide-angle end of the lens shown in Fig.
11 is an aberration diagram at the middle zoom position of the lens shown in Fig.
12 is an aberration diagram at the telephoto end of the lens shown in Fig.
13 is a lens cross-sectional view at a wide-angle end of a lens according to another embodiment.
14 is an aberration diagram at the wide-angle end of the lens shown in Fig.
15 is an aberration diagram at the middle zoom position of the lens shown in Fig.
16 is an aberration diagram at the telephoto end of the lens shown in Fig.
17 is a lens cross-sectional view at the wide-angle end of a lens according to yet another embodiment.
18 is an aberration diagram at the wide-angle end of the lens shown in Fig.
19 is an aberration diagram at the middle zoom position of the lens shown in Fig.
20 is an aberration diagram at the telephoto end of the lens shown in Fig.

Hereinafter, a zoom lens and an imaging apparatus including the zoom lens will be described in detail with reference to the accompanying drawings. In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

1 is a view showing a zoom lens according to an embodiment. The zoom lens according to the present embodiment includes, in order from the object side, a first lens group G1 having a negative refractive power, a second lens group G2 having a positive refractive power, a third lens group G2 having a negative refractive power (G3) having positive refractive power and a fourth lens group (G4) having positive refractive power. Here, G is an optical block corresponding to an optical filter, a face plate, and the like. IP represents an image surface. When the zoom lens according to the present embodiment is used as a photographing optical system of an interchangeable lens system camera, a surveillance camera, a video camera or a digital camera, a solid-state image pickup device such as a CCD sensor or a CMOS sensor Element) of the display device. When the zoom lens is used in an optical system of a silver salt film camera, the top surface IP may correspond to the film surface.

The distance between the first lens group G1 and the second lens group G2A and the distance between the first lens group G2 and the second lens group G2A Lens group G2B and the third lens group G3 and the interval between the third lens group G3 and the fourth lens group G4 are both The second lens group G2 and the third lens group G3 can be moved in the direction along the optical axis, respectively. At this time, the first lens group G1 and the fourth lens group G4 are fixed in the optical axis direction.

Further, the inner focus can be realized by giving the focusing function to the front group (the second B lens group G2B) of the second lens group G2, and the third lens group G3 can be shifted in the direction perpendicular to the optical axis So that the phase can be shifted.

Further, according to the present embodiment, it is possible to design each lens group as described below in order to realize excellent camera-shake correction and further realize an inner focus while making it a small and lightweight zoom lens.

First, the first lens group G1 includes, in order from the object side, two negative lenses whose convex surfaces are directed toward the object side and positive lenses whose convex surfaces are directed toward the object side, and the first lens group G1 have at least one surface including the aspherical shape. The first lens group G1 is configured to disperse the negative refracting power by disposing two negative lenses with the convex surface facing the object side in order from the object side, and in particular, corrects the off-axial aberration at the wide- . &Lt; / RTI &gt; In addition, since the first lens group G1 has at least one surface including the aspherical shape, it is possible to improve the off-axial aberration particularly at the wide angle position. For example, a lens including an aspherical shape may be provided on the second negative lens on the object side of the first lens group G1, and in this case, the lens having an aspherical shape can be downsized. Further, by arranging a positive lens with the convex surface facing the object side in the first lens group G1, it is possible to easily correct the chromatic aberration generated in the first lens group G1 and the spherical aberration to the telephoto end .

The first lens group G1 may be configured to satisfy the following condition.

0.3 &lt; f1 / ft &lt; 1.0 ... (Conditional Expression 1)

Here, ft is the focal length of the entire lens system at the telephoto end, and f1 is the focal length of the first lens group G1. The above conditional expression 1 defines the relationship between the focal length f1 of the first lens group G1 and the focal length ft of the entire lens system at the telephoto end. If the refractive power of the first lens group G1 is weakened beyond the upper limit value of the conditional expression 1, the lens diameter of the first lens group G1 becomes large and the thickness becomes large, which is not preferable because the zoom lens becomes large. If the refractive power of the first lens group G1 becomes stronger than the lower limit of the conditional expression 1, all aberrations can not be corrected and high performance can not be achieved, which is not preferable.

More preferably, the numerical range of the conditional expression 1 can be set as follows.

0.5 &lt; f1 / ft &lt; 0.8 ... (Conditional Expression 1a)

The second lens group G2 may include, in order from the object side, a second lens group G2A having a positive refractive power and a second B lens group G2B having a positive refractive power. The second lens group G2A may include a positive lens with a convex surface facing the object side and a negative lens with a concave surface facing the image side. Further, the second lens group G2 has at least one surface including an aspherical shape. The second lens group G2A has at least one surface including the aspherical surface shape, so that the variation of the off-axis aberration generated at the time of changing can be satisfactorily corrected. Further, the second lens group G2A is composed of a positive lens and a negative lens, so that the chromatic aberration can be satisfactorily corrected. Preferably, the negative lens group constituting the second A lens group G2A is constituted by a negative lens whose convex surface faces the object side, whereby the off-axis aberration generated at the time of changing can be satisfactorily corrected.

And the second B lens group G2B may include a cemented lens of a negative lens and a positive lens. The second lens unit G2B includes a negative lens and a positive lens in order from the object side, so that the variation of the chromatic aberration occurring at the time of focusing can be satisfactorily corrected. Preferably, the structure of the second B lens group G2B can be reduced in size by constituting a cemented lens. And the second lens sub-group G2B moves to the object side during near focusing. The solid line curve 2ba of the second B lens group G2B shows a movement trajectory for correcting the top surface variation when following the magnification from the wide-angle end to the telephoto end when being focused on an infinitely distant object. And the dotted line curve 2bb of the second B lens group G2B shows the movement trajectory for correcting the top surface variation when following the magnification from the wide-angle end to the telephoto end when being focused on the near object.

The third lens group G3 may include a cemented lens of a positive lens and a negative lens. The third lens group G3 can be configured to shift the image by shifting in a direction perpendicular to the optical axis. The third lens group G3 can be displaced in the direction perpendicular to the optical axis, thereby providing an excellent shake correction function. The third lens group G3 is composed of a positive lens and a negative lens, so that the chromatic aberration generated at the time of the phase shift can be satisfactorily corrected. Preferably, the positive lens constituting the third lens group G3 is formed in a concave meniscus shape on the object side, thereby reducing the volume and reducing the weight, thereby reducing the load on the actuator. Furthermore, the configuration can be simplified by forming it with a cemented lens.

It is preferable that the following conditional expression is satisfied for the second lens group G2 and the third lens group.

0.3 &lt; f2B / ft &lt; 1.0 ... (Conditional expression 2)

0.3 &lt; f2A / ft &lt; 1.2 ... (Conditional expression 3)

0.3 &lt; f3 / ft &lt; 1.2 (Conditional expression 4)

Here, f2A is the focal length of the second lens group G2A having the positive refractive power, which is formed on the object side in the second lens group G2, f2B is the focal length of the second lens group G2, F3 denotes a focal length of the third lens unit, and ft denotes a focal length of the entire lens system at the telephoto end.

Conditional expression 2 defines the relationship between the focal length f2B of the second B lens group G2B having the positive refractive power and the focal length ft at the telephoto end of the second lens group G2, do. The conditional expression 2 is a conditional expression for giving an optimum focusing function to the second B lens group G2B which is a focus group, and gives the second B lens group G2B a focusing function for an infinite object in a nearby object. If the upper limit of the conditional expression (2) is exceeded, the refractive power of the second B lens group G2B, which is the focus lens group, becomes excessively weak and the amount of movement in the focus function becomes large, which makes it impossible to miniaturize the zoom lens. If the lower limit value of the conditional expression (2) is exceeded, the refractive power of the second B lens group G2B, which is the focus lens group, becomes excessively strong, and the aberration variation at the time of focusing can not be corrected well.

The conditional expression (3) indicates the relationship between the focal length f2A of the second lens group G2A having positive refractive power and the focal length ft of the entire lens system at the telephoto end of the second lens group G2 And The conditional expression (3) is a conditional expression for making the focus lens group smaller while securing the performance. If the upper limit of the conditional expression (3) is exceeded, the refracting power of the second A lens group G2A becomes excessively weak and the focusing action to the second B lens group G2B having the focus function becomes weak. As a result, since the second B lens group G2B is increased, it is connected by an increase in weight and is connected by the enlargement of the zoom lens and the enlargement of the drive device. If the lower limit value of the conditional expression (3) is exceeded, the refractive power of the second lens group G2A becomes too strong, which makes it impossible to correct the aberration fluctuation at the time of changing the position.

Conditional expression 4 defines the relationship between the focal length f3 of the third lens group G3 and the focal length ft of the entire lens system at the telephoto end. Conditional expression 4 is a conditional expression for giving an optimal anti-shake function to the third lens group G3, which is the anti-vibration group. The third lens group G3 shifts at the time of image shift to correct the image blur. If the upper limit of the conditional expression (4) is exceeded, the refractive power of the third lens group (G3), which is a shift lens group, is excessively weakened and the amount of shift is increased, and the amount of work required for driving is increased, making it impossible to miniaturize the drive function. If the lower limit value of the conditional expression (4) is exceeded, the refracting power of the third lens group (G3), which is a shift lens group, becomes excessively strong, complicating the correction control of the phase shift and causing undesirable effects of image blurring.

More preferably, the numerical ranges of Conditional Expression 2, Conditional Expression 3 and Conditional Expression 4 can be set as follows.

0.5 &lt; f2B / ft &lt; 0.8 ... (Conditional expression 2a)

0.5 &lt; f2A / ft &lt; 0.9 ... (Conditional expression 3a)

0.5 &lt; f3 / ft &lt; 0.9 (Conditional expression 4a)

Next, the fourth lens group G4 may be composed of a cemented lens of a positive lens and a negative lens. The fourth lens group G4 corrects chromatic aberration by arranging positive lenses and negative lenses in order from the object side, thereby achieving high performance. In addition, preferably, by disposing a cemented lens of a positive lens and a negative lens, it is possible to reduce the influence of assembly errors at the time of manufacturing and obtain stable optical quality.

The fourth lens group G4 may satisfy the following condition. The fourth lens group G4 is preferably composed of positive lenses and negative lenses in order from the object side and satisfies the following condition.

1.5 <f4 / ft ... (Conditional expression 5)

Here, ft is the focal length of the entire lens system at the telephoto end, and f4 is the focal length of the fourth lens group G4. Conditional expression 5 is a conditional expression for ensuring the performance such as image quality for the fourth lens unit which is the final lens unit. If the refractive power of the fourth lens group G4 becomes stronger than the lower limit value of the conditional expression 5, the aberration variation at the time of changing from the wide angle end state to the telephoto end state can not be satisfactorily corrected, which is not preferable.

More preferably, the numerical range of the conditional expression 5 can be set as follows.

1.7 &lt; f4 / ft &lt; 15.0 ... (Conditional expression 5a)

If the refractive power of the fourth lens group G4 is weakened beyond the upper limit value of the conditional expression 5a and the refractive power of the fourth lens group G4 is weakened, the exit pupil can not be distanced so that a strong gradient is given to the incident light to the imaging element, It is not preferable because it is connected to image deterioration such as incidence.

Example

Examples 1 to 5 of the present invention are shown below. Table 1 below shows correspondence between each embodiment and each conditional expression.

For each numerical example, surface number i indicates the order of the optical surface on the object side. ri is the radius of curvature of the i-th optical surface, di is the surface spacing between the i-th surface and the (i + 1) th surface, and ndi and vdi denote the refractive index and Abbe number of the i- The back focus BF is a value obtained by converting the distance from the final lens surface to the paraxial upper surface in air. The total length of the lens is a value obtained by adding the back focus BF to the distance from the lens front surface to the lens final surface. The unit of length is mm. When the displacement of the optical axis direction at the position of the aspheric surface coefficient H and the aspheric surface coefficient from the optical axis to the conic constants A4, A6, A8 and A10 is set to x with respect to the surface apex, ,

.

Where R is the radius of curvature. In addition, for example, the indication of "EZ" means "10 ^-Z ". f is the focal length, Fno is the F number, and? is the half angle of view.

(Example 1)

Table 2 shows Example 1. 1 is a cross-sectional view of a lens at a wide angle end according to Numerical Embodiment 1 of the present invention. 2 is an aberration diagram of the numerical embodiment 1 at the wide angle end. Fig. 3 is an aberration diagram at the middle zoom position of the numerical embodiment 1. Fig. 4 is an aberration diagram at the telephoto end of the numerical embodiment 1. Fig.

(Example 2)

Table 3 shows Example 2. 5 is a cross-sectional view of the lens at the wide-angle end in the second embodiment. 6 is an aberration diagram at the wide-angle end of the second embodiment. 7 is an aberration diagram at the middle zoom position of the second embodiment. 8 is an aberration diagram at the telephoto end of the second embodiment.

(Example 3)

Table 4 shows the third embodiment. 9 is a cross-sectional view of the lens at the wide-angle end in the third embodiment. 10 is an aberration diagram at the wide-angle end of the third embodiment. 11 is an aberration diagram at the middle zoom position in the third embodiment. 12 is an aberration diagram at the telephoto end of the third embodiment.

(Example 4)

Table 5 shows the fourth embodiment. 13 is a sectional view of the lens at the wide-angle end in the fourth embodiment. 14 is an aberration diagram at the wide-angle end of the fourth embodiment. 15 is an aberration diagram at the middle zoom position of the fourth embodiment. 16 is an aberration diagram at the telephoto end of the fourth embodiment.

(Example 5)

Table 6 shows Example 5. 17 is a cross-sectional view of the lens at the wide-angle end in the fifth embodiment. 18 is an aberration diagram at the wide-angle end of the fifth embodiment. 19 is an aberration diagram at the middle zoom position in the fifth embodiment. 20 is an aberration diagram at the telephoto end of the fifth embodiment.

In the zoom lens according to the embodiments described above, by appropriately configuring each lens group, miniaturization can be realized while maintaining good performance during focusing, focusing, and phase shifting.

Up to now, exemplary embodiments of a zoom lens and an imaging apparatus including the zoom lens have been described and shown in the accompanying drawings to facilitate understanding of the present invention. It should be understood, however, that such embodiments are merely illustrative of the present invention and not limiting thereof. And it is to be understood that the invention is not limited to the details shown and described. Since various other modifications may occur to those of ordinary skill in the art.

G1 ... The first lens group G2, The second lens group, G3 ... The third lens group G4, The fourth lens group,
G2A ... The second lens group G2B, The second B lens group,
G ... Glass block such as CCD face plate or low pass filter, SP ... iris,
IP ... Image plane, d ... d line, g ... g line, ΔM ... Meridian upper surface, ΔS ... The thalamus,
ω ... Half angle of view, Fno ... F number

Claims (17)

In order from the object side,
A first lens group having negative refractive power;
A second lens group having positive refractive power;
A third lens group having negative refractive power; And
And a fourth lens group having positive refractive power,
The first lens group and the fourth lens group are fixed in the optical axis direction at the time of magnification from the wide angle end to the telephoto end,
The second lens group includes a second lens group having positive refractive power and a second lens group having positive refractive power in order from the object side, and moving the second lens group in the direction of the optical axis, The focusing function is given to the up-
And the image is shifted by shifting the third lens group in a direction perpendicular to the optical axis. The method according to claim 1,
The first lens group includes, in order from the object side, two negative lenses with a convex surface facing the object side and a positive lens with a convex surface facing the object side, and satisfies the following conditional expression:
0.3 <| f1 / ft | <1.0 (where f1 is the focal length of the first lens group and ft is the focal length of the entire lens system at the telephoto end). 3. The method of claim 2,
The following conditional expression:
0.5 &lt; f1 / ft &lt; 0.8. The method according to claim 1,
Wherein the second lens group includes at least one positive lens surface and at least one negative lens surface,
The second B lens group includes, in order from the object side, a negative lens and a positive lens, and satisfies the following conditional expression:
0.3 &lt; f2B / ft &lt; 1.0 and
0.3 &lt; f2A / ft &lt; 1.2, wherein f2A is a focal length of the second lens group having positive refractive power, which is formed on the object side of the second lens group, f2B is a quantity And ft is a focal length of the entire lens system at the telephoto end). 5. The method of claim 4,
The following conditional expression:
0.5 &lt; f2B / ft &lt; 0.8 and
0.5 &lt; f2A / ft &lt; 0.9. 5. The method of claim 4,
And the second lens group is composed of a positive lens having a convex surface facing the object side and a negative lens having a concave surface facing the image side. 5. The method of claim 4,
And the negative lens of the second B lens group and the positive lens are cemented lenses joined to each other. The method according to claim 1,
The third lens group includes, in order from the object side, at least one positive lens and negative lens, and satisfies the following conditional expression:
0.3 <f3 / ft <1.2, wherein f3 is the focal length of the third lens group, and ft is the focal length of the entire lens system at the telephoto end. 9. The method of claim 8,
The following conditional expression:
0.5 &lt; f3 / ft &lt; 0.9. 9. The method of claim 8,
Wherein the positive lens and the negative lens of the third lens group are cemented lenses joined to each other. 9. The method of claim 8,
And the positive lens of the third lens group has a concave meniscus shape on the object side. The method according to claim 1,
The fourth lens group includes, in order from the object side, a positive lens and a negative lens, and satisfies the following conditional expression:
1.5 <f4 / ft (where f4 is the focal length of the fourth lens group, and ft is the focal length of the entire lens system at the telephoto end). 13. The method of claim 12,
The following conditional expression:
1.7 < f4 / ft &lt; 15. 13. The method of claim 12,
Wherein the positive lens and the negative lens of the fourth lens group are cemented lenses joined to each other. The method according to claim 1,
A distance between the first lens group and the second lens group, a distance between the second lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the second lens group and the third lens group, And the second lens group and the third lens group move in the direction along the optical axis so that the interval between the third lens group and the fourth lens group is changed. A zoom lens according to any one of claims 1 to 15, And
And an imaging device that receives an optical image formed by the zoom lens and converts the optical image into an electrical image signal. A zoom lens according to any one of claims 1 to 15 as a replacement lens,
And an image pickup element for receiving an optical image formed by the zoom lens and converting the received optical image into an electric image signal.

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