JPH07152001A - Short distance correcting lens having vibrationproof function - Google Patents

Abstract

PURPOSE:To provide a short distance correcting lens which has a vibrationproof function, is small in size and high in performance and is adequate for photography, videos, etc. CONSTITUTION:This short distance correcting lens has, successively from an object side, a first lens group G1 which has a positive refracting power, a second lens group G2 which has a positive refracting power and a third lens group which is arranged on the extreme image side and has a negative refracting power. The first lens group G1 and the second lens group G2 move to the object side at the time of focusing from infinity to a short distance. The short distance correcting lens described above has a displacing means for preventing vibration by moving the third lens group G3 in a direction nearly orthogonal with the optical axis and satisfies the conditions ¦betaM¦>0.4 when the photographing magnification at the shortest object distance is defined as betaM.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a short-distance correction lens having a vibration-proof function, and more particularly to a vibration-proof method for a short-distance correction lens (so-called microlens or macrolens).

[0002]

2. Description of the Related Art Conventionally, as disclosed in JP-A-1-189621, JP-A-1-191112, and JP-A-1-191113, the shooting distance is infinity or a distance close to infinity (shooting magnification). (It is close to 0)
In some cases, the entire lens group or a part of the lens group is moved in a direction substantially orthogonal to the optical axis to correct a change in image position due to camera shake or the like. In this specification, moving the lens group in a direction substantially orthogonal to the optical axis to correct a change in image position due to camera shake or the like is referred to as “anti-vibration”.

[0003]

However, with the conventional technique as described above, image stabilization cannot be performed in a sufficiently large photographing magnification (for example, -1/2 times), and even if the photographing magnification is equal to (-). There is an inconvenience that the image stabilization cannot be performed near the (1 ×) state. It should be noted that a known document (including patent publications) does not disclose any image stabilization technology having sufficient imaging performance for the short-distance correction lens. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a short-distance correction lens having a vibration-proof function, small size, and high performance, which is suitable for photography, video, and the like. .

[0004]

In order to solve the above problems, according to the present invention, a first lens group G1 having a positive refractive power and a second lens group having a positive refractive power are arranged in order from the object side. G2 and a third lens group arranged closest to the image side and having a negative refractive power, and when focusing from infinity to a short distance, the first lens group G1 and the second lens group G2.
In the short-distance correction lens that moves toward the object side, a displacement means is provided for moving the third lens group G3 in a direction substantially orthogonal to the optical axis for vibration isolation, and the shooting magnification at the shortest shooting distance is βM. In this case, a short-distance correction lens characterized by satisfying the condition of | βM |> 0.4 is provided.

According to a preferred aspect of the present invention, the third
The focal length of the lens group G3 is fL, the focal length of the entire lens at infinity is f, and the third lens unit during image stabilization is
Assuming that the maximum displacement amount of the lens group G3 in the direction orthogonal to the optical axis is ΔSL, the condition of 0.5 <| fL | / f <5.0 ΔSL / | fL | <0.1 is satisfied. To be satisfied. Further, it is preferable that a fixed flare stop is provided on the optical axis for blocking unnecessary light rays when the third lens group moves in a direction substantially orthogonal to the optical axis for image stabilization.

[0006]

In the present invention, the first lens group G1 having a positive refractive power and the second lens having a positive refractive power are arranged in this order from the object side so as to be suitable for a short-distance correction lens for photography, video, etc. The first lens group G1 and the second lens group G2 are provided with a group G2 and a third lens group arranged closest to the image side and having a negative refractive power, when focusing from infinity to a short distance.
It adopts a configuration that moves to the object side. As a reason for adopting this configuration in the present invention, the features and advantages of this type of short-distance correction lens will be briefly described.

First, with the short-distance correction lens having the above-mentioned structure, good image forming performance can be obtained at each photographing magnification including -1/2 times and equal magnification (-1 times). Further, since the negative lens group (third lens group G3) is provided on the image side to constitute the telephoto lens type as a whole, the total lens length can be shortened as compared with the focal length of the entire lens. For this reason, in addition to being advantageous for compactness, the amount of movement of the first lens group G1 and the second lens group G2 when focusing from infinity to a short distance can be compared with that of the conventional total extension method. Since it can be made small, it is advantageous in the structure of the holding mechanism and the drive mechanism.

In addition, by the action of the negative lens group of the third lens group G3, the entire Petzval sum can be well balanced, which is advantageous for aberration correction. The present invention has found optimum conditions for image stabilization in such a short-distance correction lens suitable for photography and video.

The conditions of the present invention will be described in detail below. First of all, in the present invention, the first lens group G1 and the second lens group G2 each largely move to the object side when performing short-distance correction, that is, focusing from infinity to a short distance. Therefore, if the first lens group G1 or the second lens group G2 is an anti-vibration correction optical system that is displaced in the direction orthogonal to the optical axis, the holding mechanism and the drive mechanism become complicated and large in size, which is not preferable.

Therefore, in the present invention, the lens group closest to the image side, that is, the third lens group G3, is provided in order to simplify the mechanism of the entire lens system and to provide good aberration characteristics during image stabilization.
It adopts a structure in which a displacement means is provided in order to prevent vibration.

The short-distance correction lens of the present invention satisfies the following conditional expression (1) in addition to the above configuration. │βM │> 0.4 (1) where βM is the shooting magnification at the shortest shooting distance.

Conditional expression (1) shows the short-distance focusing ability of the optical system according to the present invention as a short-distance correction lens, and at the same time, an appropriate range () for the magnitude of the photographing magnification at the shortest photographing distance for practical use. The lower limit) is specified. If the lower limit of conditional expression (1) is not reached, the shooting magnification at the shortest shooting distance becomes too small, and the short-distance focusing ability becomes insufficient, making it unsuitable for practical use.

In order to obtain better imaging performance, it is preferable that the following conditional expressions (2) and (3) are satisfied. 0.5 <| fL | / f <5.0 (2) ΔSL / | fL | <0.1 (3) where, fL: focal length of the third lens group G3 f: total lens length at infinity Focal length ΔSL: magnitude of maximum displacement in the direction orthogonal to the optical axis of the third lens group G3 during image stabilization

Conditional expression (2) defines an appropriate range for the ratio between the focal length fL of the third lens group G3 and the focal length f of the entire lens at infinity shooting. If the upper limit of conditional expression (2) is exceeded, the focal length fL of the third lens group G3 becomes too large and the total lens length becomes long.
It is not preferable because it is against the compactness which is one of the objects of the present invention. Moreover, the curvature of the image plane and the spherical aberration tend to be excessive on the negative side, which is inconvenient.

On the contrary, if the lower limit of conditional expression (2) is exceeded,
The focal length fL of the third lens group G3 becomes too small,
As a result, the back focus becomes too short, which is inconvenient. Further, the curvature of the image plane and the spherical aberration tend to be excessive on the positive side, which is inconvenient. Further, distortion is largely generated on the positive side, which is not preferable. If the upper limit value of conditional expression (2) is set to 3 or less and the lower limit value is set to 1 or more, better imaging performance can be obtained.

Conditional expression (3) shows that the maximum displacement amount ΔSL of the third lens group G3 during image stabilization is expressed by the third lens group G3.
An appropriate range is defined by the ratio with the focal length fL of 3.
If the upper limit of conditional expression (3) is exceeded, the maximum displacement amount of the third lens group G3 during image stabilization becomes too large, and as a result, the amount of aberration variation during image stabilization becomes large. . In particular, at the peripheral position on the image plane, the difference in the optical axis direction between the best image plane in the meridional direction and the best image plane in the sagittal direction widens, which is inconvenient.

In order to obtain better imaging performance, in addition to the above-mentioned conditions, the following conditional expressions (4) and (5)
It is desirable to satisfy. 1.05 <βL <2 (4) L / f <0.5 (5) where βL: imaging magnification of the third lens group G3 L: axial thickness of the third lens group G3

Conditional expression (4) defines an appropriate range for the imaging magnification of the third lens group G3. Conditional expression (4)
Below the lower limit of, the imaging magnification of the third lens group G3 becomes too small. For this reason, the ratio of the amount of movement of the image to the amount of movement (the direction orthogonal to the optical axis) of the third lens group G3 that is the image stabilizing lens group during image stabilization becomes too small. As a result, the amount of movement of the third lens group G3, which is the image stabilizing lens group, needs to be excessively increased in order to reliably correct the movement of the image due to camera shake or the like and obtain sufficient image stabilizing performance. Therefore, it is mechanically inconvenient. On the other hand, if the upper limit of conditional expression (4) is exceeded, the spherical aberration tends to be excessive and the distortion increases toward the positive side both in the infinity state and the short-distance shooting state, which is inconvenient. is there. In conditional expression (4), the upper limit value is set to 1.6 or less,
If the lower limit value is set to 1.15 or more, even better imaging performance can be obtained.

Conditional expression (5) defines an appropriate range for the ratio of the axial thickness of the third lens group G3 to the focal length of the entire lens system at infinity. If the upper limit of conditional expression (5) is exceeded, the third lens group G, which is a vibration-proof lens group,
The axial thickness of 3 is too large, and as a result, the mechanism for vibration isolation becomes large and complicated, which is not preferable.

When actually constructing the third lens group G3,
In addition to the above-mentioned conditions, it is desirable to satisfy the following conditional expressions (6) and (7). 1.7 <N− (6) 30 <ν− (7) where N−: the maximum refractive index of the negative lens components in the third lens group G3, ν−: in the third lens group G3 Minimum Abbe number of negative lens components of

When the value goes below the lower limit of the conditional expression (6), both in the infinity state and the short-distance shooting state,
This is inconvenient because spherical aberration is likely to be excessively large and distortion is large on the positive side. In addition, the Petzval sum also tends to shift to the negative side, so that the curvature of the image surface tends to increase in the positive direction, which is inconvenient.

When the upper limit of conditional expression (7) is exceeded, in both the infinity state and the short-distance photographing state,
Axial chromatic aberration of short wavelength tends to be excessive on the positive side, and it becomes difficult to obtain good imaging performance.

In order to obtain better imaging performance, it is preferable that the following conditional expressions (8) and (9) are satisfied in addition to the above-mentioned conditions. -3 <q- <5 (8) -6 <q + <2 (9) where q + is the shape factor of the positive lens closest to the object in the third lens group G3 q-: the third lens group G3 Note the shape factor of the negative lens on the most object side in the, shape factor q is the radius of curvature of the object side surface of the lens and r _a, the radius of curvature of the image side surface of the lens r
_{When b} is given, it is given by the following mathematical expression (a). q = (r _b + r _a ) / (r _b −r _a ) (a)

When the value goes below the lower limit of conditional expression (8), in both the infinity state and the short-distance shooting state,
This is inconvenient because spherical aberration tends to be excessive on the positive side and distortion increases on the positive side. On the other hand, when the value exceeds the upper limit of conditional expression (8), outward coma is generated in a ray above the principal ray in both the infinity state and the short-distance photographing state, which is inconvenient.

When the value goes below the lower limit of conditional expression (9), in both the infinity state and the short-distance photographing state,
This is inconvenient because the spherical aberration tends to become excessively negative and the distortion becomes large on the negative side. On the other hand, if the upper limit of conditional expression (9) is exceeded, spherical aberration tends to become negative excessively in both cases of infinity and short-distance shooting, and a coma inwardly directed to a ray above the chief ray. This is inconvenient because aberration occurs.

If a fixed flare stop is provided on the optical axis in addition to the aperture stop, unnecessary light rays can be shielded when the lens group is displaced across the optical axis for vibration isolation, and ghost It is possible to prevent the occurrence of the occurrence and unnecessary exposure. Further, it is desirable that the third lens group G3 be fixed along the optical axis when focusing on a short distance so that the holding mechanism and the driving mechanism can be simplified.

When focusing on a short distance, the first lens group G should be used in order to sufficiently correct aberrations and obtain good imaging performance.
It is desirable that the first and second lens groups G2 have a configuration that is nearly symmetrical with respect to the aperture stop. More specifically, the most image-side surface of the first lens group G1 is a divergent surface that is convex toward the object side, and the most object-side surface of the second lens group G2 is a divergent surface that is convex toward the image side. Is desirable. Further, the first lens group G1
It is desirable that the lens closest to the object side is a positive meniscus lens having a convex surface facing the object side.

When the third lens group G3 is made up of two lenses, it is desirable that it be made up of a negative lens and a positive lens. More specifically, it is desirable to use a negative lens having a strong concave surface facing the object side and a biconvex lens.
When the third lens group G3 is composed of three lenses, it is desirable that the third lens group G3 be composed of one negative lens and two positive lenses. More specifically, it is desirable that the positive lens has a strong convex surface facing the image side, a biconcave lens, and a positive lens having a strong convex surface facing the object side.

In order to achieve good chromatic aberration correction when focusing at a short distance, the first positive refractive power that moves when focusing at a short distance is used.
It is necessary to achromatize each lens group of the lens group G1 and the second lens group G2. Therefore, at least one lens component having a negative refractive power is required in each lens group. At this time, in any of the first lens group G1 and the second lens group G2, the minimum Abbe number ν m of the Abbe numbers of the negative lens component preferably satisfies the following conditional expression (10). . νm <37 (10)

In order to further enhance the image forming performance, it is important to distribute the refractive power between the first lens group G1 and the second lens group G2. The focal length of the first lens group G1 and the second lens group G2 If the focal lengths are f1 and f2 respectively,
It is preferable that the following conditional expression (11) is satisfied. 1.5 <f1 / f2 <2.5 (11)

It is also possible to use a part of the third lens group G3 or a part of the lens groups as an image stabilization group. Further, as the shooting magnification increases, the depth on the side of the object field becomes shallower, which causes the inconvenience of being easily out of focus. In this case, by combining the autofocus system and the short distance correction lens of the present invention, it is possible to avoid the defocus.

[0032]

EXAMPLE A short-distance correction lens having an image stabilizing function according to the present invention in each example has a first lens group G1 having a positive refractive power and a second lens group having a positive refractive power in order from the object side.
A first lens group G1 and a second lens group G2 are provided, which include a lens group G2 and a third lens group arranged closest to the image side and having a negative refractive power, when focusing from infinity to a short distance.
In the short-distance correction lens that moves toward the object side, the displacement means 1 is provided for moving the third lens group G3 in a direction substantially orthogonal to the optical axis to perform image stabilization.

Each embodiment of the present invention will be described below with reference to the accompanying drawings. [Embodiment 1] FIG. 1 is a diagram showing the structure of a short-distance correction lens according to the first embodiment of the present invention. The illustrated short-distance correction lens includes, in order from the object side, a first lens group G1 including a biconvex lens, a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a convex surface facing the object side, and a biconcave lens and a biconcave lens. The second lens group G2 includes a cemented lens with a convex lens and a biconvex lens, and the third lens group G3 includes a biconvex lens and a biconcave lens. An aperture stop S is provided between the first lens group G1 and the second lens group G2 as shown in the figure.

FIG. 1 shows the positional relationship between the lens groups in the infinity state. When focusing on a short distance, the lens groups move on the optical axis along the trajectory shown by the arrow in the figure. However, the third lens group G3 is fixed in the optical axis direction, and is appropriately moved in a direction substantially orthogonal to the optical axis by the image stabilizing mechanism 1 which is a displacement means so that the image shake caused by camera shake or the like is corrected. It has become. Example 1 is an application of the present invention to a photographic lens having a relatively short focal length.

The following table (1) lists the values of specifications of the first embodiment of the present invention. In Table (1), f is the focal length at infinity, β is the shooting magnification at short range, and F _NO
Represents the F number in the infinite state, 2ω represents the angle of view in the infinite state, and Bf represents the back focus. Furthermore, the leftmost number indicates the order of each lens surface from the object side, r
Is the radius of curvature of each lens surface, d is the distance between each lens surface, n
And ν indicate the refractive index and the Abbe number for the d-line (λ = 587.6 nm).

[0036]

Table 1 f = 599.9998 F _NO = 2.82 2ω = 39.4 ° (Anti-vibration data) Shooting magnification at infinity Shooting magnification (-1) (-1/2) Moving amount of anti-vibration lens group in the direction orthogonal to the optical axis (mm) 1.00 1.00 1.00 Moving amount of image ( mm) -0.20 -0.20 -0.20 (The negative sign of the amount of movement of the image indicates the direction opposite to the moving direction of the lens) (Values corresponding to conditions) (1) | βM | = 1.000 (2) | fL | / f = 2.820 (3) △ SL / | fL | = 0.0059 (4) βL = 1.20 (5) L / f = 0.12 (6) N- = 1.79631 (7) ν- = 40.90 (8) q- = 0.680 (9) q + = -0.758 (10) νm = 35.70 (G1), 30.05 (G2) (11) f1 / f2 = 1.803

FIGS. 2 to 4 are graphs showing various aberrations at infinity, various aberrations at a photographing magnification of -1/2, and various aberrations at a uniform photographing magnification (-1). It is a figure. In each aberration diagram, F _NO is the F number, Y is the image height, NA is the numerical aperture, and D is the d-line (λ = 5).
87.6 nm) and G indicates the g-line (λ = 435.8 nm). Further, in the aberration diagram showing astigmatism, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. As is clear from each aberration diagram, in the present example, it is understood that various aberrations are well corrected including in the case of image stabilization.

[Embodiment 2] FIG. 5 is a diagram showing a structure of a short-distance correction lens according to a second embodiment of the present invention. The short-distance correction lens shown in the figure is a biconvex lens in order from the object side.
A first lens group G1 including a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, a negative meniscus lens having a concave surface facing the object side, and a positive meniscus lens having a concave surface facing the object side. A second lens group G2 including a cemented lens with a lens and a biconvex lens;
The third lens group G3 includes a positive meniscus lens having a concave surface facing the object side, a biconcave lens, and a biconvex lens. The first lens group G1 and the second lens group G
An aperture stop S is provided between the two as shown.

FIG. 5 shows the positional relationship of each lens group in the infinite state, and when focusing on a short distance, it moves along the optical axis along the trajectory shown by the arrow in the figure. However, the third lens group G3 is fixed in the optical axis direction, and is appropriately moved in a direction substantially orthogonal to the optical axis by the image stabilizing mechanism 1 which is a displacement means so that the image shake caused by camera shake or the like is corrected. It has become. Example 2 is an application of the present invention to a photographic lens having a longer focal length than that of Example 1, and has the same basic configuration as the short-distance correction lens of Example 1 described above, but each lens The refractive power and shape of the groups are different.

The following table (2) lists the values of specifications of the second embodiment of the present invention. In Table (2), f is the focal length at infinity, β is the shooting magnification at short range, and F _NO
Represents the F number in the infinite state, 2ω represents the angle of view in the infinite state, and Bf represents the back focus. Furthermore, the leftmost number indicates the order of each lens surface from the object side, r
Is the radius of curvature of each lens surface, d is the distance between each lens surface, n
And ν indicate the refractive index and the Abbe number for the d-line (λ = 587.6 nm).

[0041]

[Table 2] f = 105 F _NO = 2.86 2ω = 23.06 ° (Anti-vibration data) Shooting magnification at infinity Shooting magnification (-1) (-1/2) Moving amount of anti-vibration lens group in the direction orthogonal to the optical axis (mm) 1.00 1.00 1.00 Moving amount of image ( mm) −0.249 −0.249 −0.249 (The negative sign of the amount of movement of the image indicates the direction opposite to the moving direction of the lens) (Values corresponding to conditions) (1) | βM | = 1.000 (2) | fL | / f = 1.782 (3) △ SL / | fL | = 0.0053 (4) βL = 1.249 (5) L / f = 0.234 (6) N- = 1.79631 (7) ν- = 40.90 (8) q- = 0.287 (9) q + = -4.427 (10) νm = 35.70 (G1), 33.75 (G2) (11) f1 / f2 = 2.142

FIGS. 6 to 8 are graphs showing various aberrations in the state of infinity, various aberrations in the state where the photographing magnification is −1/2, and various aberrations in the state where the photographing magnification is equal (−1). It is a figure. In each aberration diagram, F _NO is the F number, Y is the image height, NA is the numerical aperture, and D is the d-line (λ = 5).
87.6 nm) and G indicates the g-line (λ = 435.8 nm). Further, in the aberration diagram showing astigmatism, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. As is clear from each aberration diagram, in the present example, it is understood that various aberrations are well corrected including in the case of image stabilization.

[Third Embodiment] FIG. 9 is a diagram showing the structure of a short-distance correction lens according to a third embodiment of the present invention. The short-distance correction lens shown in the figure is a biconvex lens in order from the object side.
A first lens group G1 including a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a second lens group including a cemented lens of a biconcave lens and a biconvex lens and a biconvex lens. The third lens group G3 includes a positive meniscus lens having a concave surface facing the object side, a biconcave lens, a biconvex lens, and a negative meniscus lens having a convex surface facing the object side. In addition, between the first lens group G1 and the second lens group G2,
An aperture stop S is provided as shown.

FIG. 9 shows the positional relationship of each lens group in the infinite state, and when focusing on a short distance, it moves along the optical axis along the trajectory shown by the arrow in the figure. However, the third lens group G3 is fixed in the optical axis direction, and is appropriately moved in a direction substantially orthogonal to the optical axis by the image stabilizing mechanism 1 which is a displacement means so that the image shake caused by camera shake or the like is corrected. It has become. Example 3 is an application of the present invention to a photographic lens having a longer focal length than that of Example 1, and has the same basic structure as the short-distance correction lens of Example 1 described above, but each lens The refractive power and shape of the groups are different.

Table (3) below lists values of specifications of the third embodiment of the present invention. In Table (3), f is the focal length at infinity, β is the shooting magnification at short range, and F _NO
Represents the F number in the infinite state, 2ω represents the angle of view in the infinite state, and Bf represents the back focus. Furthermore, the leftmost number indicates the order of each lens surface from the object side, r
Is the radius of curvature of each lens surface, d is the distance between each lens surface, n
And ν indicate the refractive index and the Abbe number for the d-line (λ = 587.6 nm).

[0046]

Table 3 f = 105.0000 F _NO = 2.80 2ω = 23.14 ° (Anti-vibration data) Shooting magnification at infinity (-1/2) Amount of movement of the anti-vibration lens group in the direction orthogonal to the optical axis (mm) 1.20 1.20 Amount of image movement (mm) -0.480-0. 480 (The negative sign of the moving amount of the image shows the direction opposite to the moving direction of the lens) (Value corresponding to the condition) (1) | βM | = 0.500 (2) | fL | / f = 1.129 (3) ΔSL / | fL | = 0.0101 (4) βL = 1.400 (5) L / f = 0.211 (6) N- = 1.80454 (7) ν- = 39.61 (8) q- = -0.384 (9) q + = -1.777 (10) ) Νm = 35.19 (G1), 31.15 (G2) (11) f1 / f2 = 1.894

FIG. 10 and FIG. 11 are graphs showing various aberrations in the state of infinity and graphs in the state where the photographing magnification is -1/2. In each aberration diagram, F _NO is F
No., Y is the image height, NA is the numerical aperture, D is the d-line (λ = 587.6 nm), and G is the g-line (λ = 435.8).
nm) respectively. Further, in the aberration diagram showing astigmatism, the solid line shows the sagittal image plane and the broken line shows the meridional image plane. As is clear from each aberration diagram, in the present example, it is understood that various aberrations are well corrected including in the case of image stabilization.

[0048]

As described above, according to the present invention, it is possible to provide a small-sized, high-performance short-distance correction lens suitable for photography and video, which is provided with a vibration-proof function. For this reason, hand-held photography becomes possible, which is extremely convenient at the time of actual photography, and photography can also be performed with good imaging performance under vibration conditions caused by camera shake or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a short-distance correction lens according to Example 1 of the present invention.

FIG. 2 is a diagram of various types of aberration in the infinite state of the first example of FIG.

FIG. 3 is a diagram of various types of aberration when the imaging magnification of the first example of FIG. 1 is −1/2.

FIG. 4 is a same magnification (-1 ×) as the photographing magnification of the first embodiment of FIG.
FIG. 6 is a diagram of various aberrations in the state of FIG.

FIG. 5 is a diagram showing a configuration of a short-distance correction lens according to Example 2 of the present invention.

FIG. 6 is a diagram of various types of aberration in the infinite state of the second example of FIG.

FIG. 7 is a diagram of various types of aberration in the second example of FIG. 5 at a photographing magnification of −1/2.

FIG. 8 is a photographing magnification of 1 × (−1 ×) in the second embodiment of FIG.
FIG. 6 is a diagram of various aberrations in the state of FIG.

FIG. 9 is a diagram showing a configuration of a short-distance correction lens according to Example 3 of the present invention.

FIG. 10 is a diagram of various types of aberration in the infinite state of the third example of FIG.

FIG. 11 is a diagram of various types of aberration in the third embodiment of FIG. 9 when the imaging magnification is −1/2.

[Explanation of symbols]

 G1 First lens group G2 Second lens group G3 Third lens group 1 Displacement means (anti-vibration mechanism) S Aperture stop

Claims (7)

[Claims] 1. A first lens group having a positive refracting power, a second lens group having a positive refracting power, and a third lens group having a negative refracting power arranged closest to the image side, in order from the object side. And a short-distance correction lens in which the first lens group and the second lens group move to the object side when focusing from infinity to a short distance, in a direction substantially orthogonal to the optical axis of the third lens group. A short-distance correction lens, which is provided with a displacement means for moving the lens to prevent vibration and satisfies the condition of | βM |> 0.4, where βM is the shooting magnification at the shortest shooting distance. 2. The short-distance correction lens according to claim 1, wherein the third lens group is fixed along the optical axis when focusing on a short distance. 3. A focal length of the third lens group is fL, a focal length of the entire lens at infinity is f, and a maximum displacement amount in a direction orthogonal to an optical axis of the third lens group during image stabilization. 3. When the magnitude of ΔSL is ΔSL, the condition of 0.5 <| fL | / f <5.0 ΔSL / | fL | <0.1 is satisfied. 3. Short-distance correction lens. 4. When the imaging magnification of the third lens group is β L, the axial thickness of the third lens group is L, and the focal length of the entire lens at infinity is f, then 1.05 < The short-distance correction lens according to any one of claims 1 to 3, which satisfies a condition of β L <2 L / f <0.5. 5. The maximum refractive index of the negative lens components in the third lens group is N-, and the minimum Abbe number of the negative lens components in the third lens group is ν.
-, The short-distance correction lens according to any one of claims 1 to 4, wherein the condition of 1.7 <N-30 <ν- is satisfied. 6. The shape factor of the positive lens closest to the object side in the third lens group is q +, and the shape factor of the negative lens closest to the object side in the third lens group is q +.
The short-distance correction lens according to any one of claims 1 to 5, wherein the condition of -5 <q- <5-6 <q + <2 is satisfied. 7. A fixed flare diaphragm is provided on the optical axis for blocking unnecessary light rays when the third lens group moves in a direction substantially orthogonal to the optical axis for image stabilization. The short-distance correction lens according to any one of claims 1 to 6, which is characterized in that.