JPH08220427A - Wide angle lens having vibration proof function - Google Patents

Abstract

PURPOSE: To provide a small and high performance wide angle lens which has a vibration proof function and is suitable for photographic and video applications. CONSTITUTION: This lens is provided with a lens group GF having a negative refractive power and a lens group GL having a positive refractive power. The back focus of the lens is longer than the focal distance of the entire optical system and as a whole, the lens has a positive refractive power. A partial lens group GLP having a positive refractive power among the group GL has at least a positive meniscus lens and a lens having both convex surfaces. The group GLP is provided with a displacement means which rotatably moves the group GLP centered around the point on the optical axis separated from a prescribed distance from the closest image side surface of the GLP toward an object side for a vibration proof purpose. Let the focal distance of the group GLP be fLP and the focal distance of the entire lens system during the photographing of a point at infinity be (f), then the wide angle lens satisfies the 0.3<fLP/f<5.0 condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide-angle lens having an anti-vibration function, and more particularly to an anti-vibration method for wide-angle lenses and ultra-wide-angle lenses for photography and video.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 1-191112 and Japanese Patent Application Laid-Open No. 2-103014, there is known an image stabilization technique for a lens having a relatively short back focus. In this specification, moving the lens group across the optical axis to correct the variation in image position due to camera shake or the like is referred to as “anti-vibration”.

[0003]

However, for a wide-angle lens or an ultra-wide-angle lens having a sufficiently long back focus such as a camera lens for a single-lens reflex camera, an anti-vibration technique having a good image forming performance has not yet been proposed. Absent. The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a wide-angle lens having a vibration-proof function, small size, and high performance, which is suitable for photography, video, and the like.

[0004]

To solve the above problems, in the present invention, a lens group GF having a negative refractive power and a lens group G having a positive refractive power are sequentially arranged from the object side.
In the wide-angle lens having a back focus longer than the focal length of the entire optical system and having a positive refracting power as a whole, the partial lens group GLP having a positive refracting power in the lens group GL is At least a positive meniscus lens having a convex surface directed toward the image side and a biconvex lens are provided, and a point on the optical axis, which is spaced a predetermined distance toward the object side from the most image side surface of the partial lens group GLP, is the center. Displacement means for rotating the partial lens group GLP for vibration isolation is provided, and when the focal length of the partial lens group GLP is fLP and the focal length of the entire lens system in the infinity shooting state is f, Provided is a wide-angle lens having a vibration-proof function, which satisfies 0.3 <fLP / f <5.0.

According to a preferred embodiment of the present invention, the lens group GF has a negative meniscus lens having a convex surface directed toward the object side, and the partial lens group GLP is disposed on the most image side of the lens group GL and has The magnitude of the maximum rotation angle .DELTA.WL (rad) of the partial lens group GLP at the time of shaking satisfies the condition .DELTA.WL <0.1.

[0006]

In the present invention, in order from a wide-angle lens and a super-wide-angle lens for photography, video, etc., in order from the object side,
A wide-angle lens having a lens group GF having a negative refracting power and a lens group GL having a positive refracting power and having a back focus longer than the focal length of the entire optical system and having a positive refracting power as a whole is constructed. It is adopted. As a reason for adopting this configuration in the present invention, the features and advantages of this type of wide-angle lens and ultra-wide-angle lens will be briefly described.

First, in general, the aberration of the lens has a property of increasing as the angle of view increases, and the imaging performance is impaired. However, with the wide-angle lens of the type described above, good imaging performance can be obtained. Further, since the object side has the lens group GF having negative refractive power and the image side has the lens group GL having positive refractive power, it is possible to secure a large back focus as compared with the focal length of the entire optical system. it can. Therefore, the lens of the type described above is usually suitable for a single lens reflex camera lens or the like having a configuration in which the back focus is longer than the focal length. This is why it is called the retro focus type.

In addition, due to the action of the negative lens group GF described above, the entire Petzval sum can be well balanced. The present invention has found optimum conditions for image stabilization in a wide-angle lens of the type described above.

The constitutional conditions of the present invention will be described in detail below.
In the above lens type, the object side lens group GF tends to be large. Therefore, if the lens group GF is a vibration-proof lens group that is displaced across the optical axis for vibration prevention, the holding mechanism and the drive mechanism become complicated and the size becomes large, which is not preferable. Therefore, in the present invention, the lens group GL having a positive refracting power on the image side is provided in order to simplify the mechanism of the entire lens system and to obtain good aberration characteristics during image stabilization.
Displacement means for vibration isolation is provided in a partial lens group GLP having a positive refractive power.

Further, if the partial lens group GLP, which is the image stabilizing lens group, is constructed by one single lens, the aberrations produced are too large, which is inconvenient. Therefore, in order to obtain good image forming performance as the entire optical system, it is necessary to configure the partial lens group GLP with a plurality of lenses. In the present invention, it has been found that the partial lens group GLP preferably has at least a positive meniscus lens having a convex surface facing the image side and a biconvex lens having a strong refractive power surface facing the object side.

Further, in order to obtain a good image-forming performance even during image stabilization, it is not enough to move (shift) the image stabilization lens group in a direction perpendicular to the optical axis. In the present invention, it has been found that it is preferable to rotationally move the anti-vibration lens group around the point on the optical axis on the object side as the center of rotation. If a fixed flare stop is provided on the optical axis in addition to the aperture stop, unnecessary rays can be shielded when the anti-vibration lens group GLP is displaced across the optical axis for anti-vibration. It is possible to prevent the occurrence of the occurrence and unnecessary exposure. It is also preferable that the lens group GF has a negative meniscus lens having a convex surface directed toward the object side, in order to obtain good imaging performance.

Each conditional expression of the present invention will be described below. The wide-angle lens of the present invention satisfies the following conditional expression (1). 0.3 <fLP / f <5.0 (1) where, fLP: focal length of partial lens group GLP f: focal length of entire lens system in infinity shooting state

Conditional expression (1) indicates an appropriate range of the ratio of the focal length fLP of the image stabilizing lens group GLP to the focal length f of the entire lens system. If the upper limit of conditional expression (1) is exceeded, the focal length fLP of the antivibration lens group GLP becomes too large and the overall lens length tends to become long, which is against the compactness which is one of the objects of the present invention. . Furthermore, spherical aberration tends to be excessive on the positive side,
It is inconvenient.

On the contrary, if the lower limit of conditional expression (1) is exceeded,
The focal length fLP of the anti-vibration lens group GLP becomes too small,
The spherical aberration tends to be excessive on the negative side. In addition, the Petzval sum tends to largely shift to the positive side, and as a result, the curvature of the image surface tends to occur in the negative direction, which is also inconvenient. In order to obtain a better imaging performance, it is preferable to set the upper limit value of conditional expression (1) to 2.0 and the lower limit value to 0.5.

Further, in the present invention, the lens group GF has a negative meniscus lens having a convex surface directed toward the object side, the partial lens group GLP is disposed on the most image side of the lens group GL, and the following conditional expression (2) ) Is preferably satisfied. ΔWL <0.1 (rad) (2) where ΔWL is the maximum rotation angle (rad) of the partial lens group GLP during image stabilization.

Conditional expression (2) defines an appropriate range of the maximum rotation angle of the image stabilizing lens group GLP. If the upper limit of conditional expression (2) is exceeded, the maximum rotation amount of the image stabilizing lens group GLP during image stabilization becomes too large. As a result, the amount of aberration variation during image stabilization becomes large, which is inconvenient. In particular, 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 near the center on the image plane widens, which is inconvenient. It should be noted that in order to obtain even better imaging performance, the upper limit of conditional expression (2) should be 0.03.
(Rad) is preferable.

Further, in order to obtain further excellent image forming performance and image stabilizing performance, it is desirable that the following conditional expressions (3) and (4) are satisfied. 0.2 <f1 / fF <4.0 (3) L / f <0.7 (4) where f1: focus of the most object-side negative meniscus lens with the convex surface facing the object side in the lens group GF. Distance fF: Focal length of lens group GF L: On-axis thickness of anti-vibration lens group GLP

Conditional expression (3) defines an appropriate range for the ratio between the focal length of the negative meniscus lens closest to the object side with the convex surface facing the object side in the lens group GF and the focal length of the lens group GF. ing. If the upper limit of conditional expression (3) is exceeded, the back focus tends to become short, which is not preferable. In addition, the curvature of the image surface tends to occur in the negative direction, which is inconvenient.

On the contrary, if the lower limit of conditional expression (3) is exceeded,
This is inconvenient because spherical aberration tends to be excessively large, and distortion tends to increase toward the positive side. In order to obtain even better imaging performance, it is preferable to set the upper limit value of conditional expression (3) to 2.0 and the lower limit value to 0.4.

Conditional expression (4) defines an appropriate range for the ratio of the axial thickness of the image stabilizing lens group GLP to the focal length of the entire lens system. If the upper limit of conditional expression (4) is exceeded, the axial thickness of the antivibration lens group GLP becomes too large,
This is inconvenient because the vibration isolation mechanism becomes large and complicated. In addition, in order to further downsize and simplify the mechanism for vibration isolation, the upper limit of conditional expression (4) is set to 0.
It is preferably 35.

When actually constructing the image stabilizing lens group GLP, it is desirable that the following conditional expressions (5) to (8) are satisfied. 1.5 <N− (5) 40 <ν + (6) −3.0 <(R2 + R1) / (R2-R1) <0 (7) 0 <D / fLP <10.0 (8)

Here, N-: refractive index of the most object-side negative meniscus lens having a convex surface facing the object side in the lens group GF +: Abbe number R1: of the most image-side biconvex lens in the lens group GL The radius of curvature of the most object-side surface of the most object-side positive meniscus lens in the image stabilizing lens group GLP: the radius of curvature of the most image-side surface of the most object-side positive meniscus lens in the image stabilizing lens group GLP D: The distance along the optical axis from the most image-side surface of the image stabilizing lens group GLP to the rotation center point. The refractive index and the Abbe number of the lens are d line (λ = 5
(87.6 nm). Further, when the positive meniscus lens closest to the object in the image stabilizing lens group GLP includes an aspherical surface, R1 and R2 indicate their paraxial radii of curvature.

Conditional expression (5) defines an appropriate range for the refractive index of the most object-side negative meniscus lens having the convex surface facing the object side in the lens group GF. If the lower limit of conditional expression (5) is not reached, spherical aberration tends to be positively excessive both in the infinity shooting state and in the image stabilization state.
Distortion aberration increases to the positive side, which is inconvenient. In addition, since the Petzval sum also tends to shift to the negative side, the curvature of the image plane in the positive direction tends to become large, which is inconvenient.

Conditional expression (6) defines an appropriate range for the Abbe number of the most image-side biconvex lens in the lens group GL. When the value goes below the lower limit of conditional expression (6), axial chromatic aberration of short wavelength tends to be excessive on the positive side in both the infinity shooting state and the image stabilization state, and it is difficult to obtain good imaging performance. Become.

Conditional expression (7) defines an appropriate range for the shape factor of the positive meniscus lens closest to the object in the image stabilizing lens group GLP. If the upper limit of conditional expression (7) is exceeded, the curvature of the image plane becomes excessively large on the positive side, which is inconvenient. In addition, it becomes difficult to correct coma aberration. On the other hand, when the value goes below the lower limit of conditional expression (7), the curvature of the image plane becomes excessively large on the positive side, which is inconvenient. Also,
It becomes difficult to correct coma.

Regarding the position of the center of rotation during vibration isolation,
As described above, it is preferable that the point on the optical axis which is spaced from the surface of the image stabilizing lens group GLP closest to the image side to the object side by a predetermined distance is preferable. Here, the conditional expression (8) defines the position of the rotation center at the time of vibration isolation in order to obtain better vibration isolation performance. If the range defined by the conditional expression (8) is exceeded, the fluctuation of coma aberration during image stabilization becomes large, which is not preferable. In particular, 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 on the periphery of the image plane widens, which is inconvenient.

When the antivibration lens group GLP is composed of two lenses, it is composed of, in order from the object side, a positive meniscus lens having a convex surface facing the object side and a biconvex lens having a strong refractive power surface facing the object side. It is desirable to do. Further, in order to simplify the holding mechanism and the driving mechanism, it is preferable to fix the image stabilizing lens group GLP along the optical axis when focusing on a short-distance object.

Further, by disposing a positive meniscus lens having a convex surface facing the object side on the most object side of the lens group GF, distortion can be effectively corrected. Further, in order to achieve good plane characteristics of the image plane during image stabilization, when the Petzval sum of the image stabilization lens group GLP is PLP and the Petzval sum of the entire lens system is PA, the following conditional expression (9) is obtained. It is preferable to be satisfied. 0 <PLP / PA <8.0 (9)

Further, in order to secure a sufficiently large back focus and achieve a good aberration balance, it is preferable to satisfy the following conditional expressions (10) and (11). 0.3 <| fF | / fL <3.0 (10) 0.7 <fL / f <3.0 (11) where, fL: focal length of lens group GL

Focusing on a short-distance object can also be achieved by a system in which the entire optical system is fed out integrally or by dividing the entire optical system into a plurality of lens groups and moving each lens group along the optical axis. It is possible depending on the method. The lens adjacent to the object side of the image stabilizing lens group GLP is preferably a biconcave lens. Further, the aperture stop is a lens group G.
Positioning in L or near the lens group GL is desirable. Further, it is preferable that the surface adjacent to the image side of the aperture stop is a strongly divergent surface. Further, if an aspherical surface, a gradient index glass, or the like is used for any of the lenses of the optical system including the image stabilizing lens group, more excellent optical performance can be obtained.

[0031]

EXAMPLE A wide-angle lens having a vibration-proof function according to the present invention is provided with a lens group GF having a negative refracting power and a lens group GL having a positive refracting power in this order from the object side. In a wide-angle lens whose back focus is longer than the focal length of the entire optical system and has a positive refracting power as a whole, some of the partial lens groups GLP having a positive refracting power in the lens group GL are at least on the image side. It has a positive meniscus lens having a convex surface and a biconvex lens. And
Displacement means 1 for rotating and moving the partial lens group GLP about a point P on the optical axis, which is spaced a predetermined distance toward the object side from the most image side surface of the partial lens group GLP, is provided. I have it.

Each embodiment of the present invention will be described below with reference to the accompanying drawings. [Embodiment 1] FIG. 1 is a view showing the arrangement of a wide-angle lens according to the first embodiment of the present invention. The wide-angle lens shown in the figure is a lens group GF composed of, in order from the object side, a biconvex lens and a negative meniscus lens having a convex surface facing the object side, a biconvex lens, a biconcave lens, a positive meniscus lens having a convex surface facing the image side, and It is composed of a lens group GL composed of biconvex lenses.

Two lenses of the lens group GL arranged on the image side, that is, a positive meniscus lens having a convex surface facing the image side and a biconvex lens, constitute a vibration-proof lens group GLP. A fixed flare stop FS is provided between the lens group GF and the lens group GL, and an aperture stop S is provided in the lens group GL. The anti-vibration lens group GLP is appropriately rotated and moved around the point P by the anti-vibration mechanism 1 which is a displacing means, and image shake caused by camera shake or the like is corrected. Example 1 is an application of the present invention to a wide-angle photographic lens.

The following table (1) shows the values of specifications of the first embodiment of the present invention. In Table (1), f is the focal length in the infinity shooting state, and FNO is the F in the infinity shooting state.
The number and Bf represent back focus. further,
The leftmost number is the order of the lens surfaces from the object side, r is the radius of curvature of each lens surface, d is the distance between the lens surfaces, and n is the distance between the lens surfaces.
(D) and ν are d lines (λ = 587.6 nm), respectively.
The refractive index and the Abbe number for n (G) are g-lines (λ
= 435.8 nm).

[0035]

[Table 1] f = 28.597 FNO = 2.86 rd ν n (D) n (G) 1 137.0556 3.0000 33.75 1.648310 1.673230 2 -4002.6300 0.2000 3 62.3678 2.0000 58.50 1.651600 1.665390 4 15.2995 21.1000 5 ∞ 1.1000 (fixed flare Aperture FS) 6 26.6224 6.3000 45.37 1.796680 1.818800 7 -60.5608 1.4000 8 ∞ 3.6000 (Aperture stop S) 9 -26.7885 5.6000 26.05 1.784700 1.824530 10 33.7247 1.1500 11 -77.1041 2.2000 55.60 1.696800 1.712320 12 -22.2069 0.1000 13 84.6383 3.0000 53.93 141.71 3000 47.0415 38.0829 (Bf) (Anti-vibration data) Infinity shooting condition Maximum rotation angle (rad) of anti-vibration lens group 0.00611 Image movement amount +0.136 (Indicates the same direction) (Condition corresponding value) f = 28.597 fF = −38.231 fL = 29.093 fLP = 21.890 ΔWL = 0.00611 L = 5.3 f1 = − 31.642 D = 14.45 (1) fLP / f = 0.765 (2) ΔWL = 0.00611 (3) f1 / fF = 0.828 (4) L / f = 0.185 (5) N -= 1.65160 (6) ν + = 53.89 (7) (R2 + R1) / (R2-R1) = -1.650 (8) D / fLP = 0.660 (9) PLP / PA = 5. 419 (10) | fF | /fL=1.314 (11) fL / f = 1.017

FIG. 2 is a diagram of various aberrations of Example 1 in the infinity imaging state. In each aberration diagram, FNO is the F number, Y is the image height, and D is the d line (λ = 587.6 nm).
, G represents 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. 3 is a diagram showing a structure of a wide-angle lens according to a second embodiment of the present invention. The wide-angle lens shown in the figure is a lens group GF composed of, in order from the object side, a positive meniscus lens having a convex surface facing the object side, a negative meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a convex surface facing the object side. , A plano-convex lens having a convex surface facing the object side, a plano-convex lens having a convex surface facing the image side, a biconcave lens, a positive meniscus lens having a convex surface facing the image side, and a lens group GL including a biconvex lens.

The two lenses of the lens group GL arranged on the image side, that is, the positive meniscus lens having a convex surface directed toward the image side and the biconvex lens, constitute the antivibration lens group GLP. An aperture stop S is provided in the lens group GL. The anti-vibration lens group GLP is appropriately rotated and moved around the point P by the anti-vibration mechanism 1 which is a displacing means, and image shake caused by camera shake or the like is corrected. Example 2 is applied to a wide-angle photographic lens having the same focal length as that of Example 1.

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 in the infinity shooting state, and FNO is the F in the infinity shooting state.
The number and Bf represent back focus. further,
The leftmost number is the order of the lens surfaces from the object side, r is the radius of curvature of each lens surface, d is the distance between the lens surfaces, and n is the distance between the lens surfaces.
(D) and ν are d lines (λ = 587.6 nm), respectively.
The refractive index and the Abbe number for n (G) are g-lines (λ
= 435.8 nm).

[0040]

[Table 2] f = 28.610 FNO = 2.89 rd ν n (D) n (G) 1 60.5000 3.5000 47.07 1.670030 1.688060 2 118.3000 0.1000 3 36.9000 1.5000 64.10 1.516800 1.526690 4 15.4000 4.0000 5 28.2000 1.5000 64.10 1.516800 1.526690 6 15.1300 14.4000 7 28.6000 4.4000 41.96 1.667550 1.687870 8 ∞ 1.3500 9 ∞ 4.0000 60.14 1.620410 1.633140 10 -33.9700 1.0000 11 ∞ 4.3000 (Aperture stop S) 12 -20.8000 2.5500 27.61 1.755200 1.791120 13 53.1800 1.0000 14 -46.0010 3.1000 57.53 1.670250 0.184660 15 15 16 109.0970 3.5000 57.53 1.670250 1.684660 17 -34.8000 38.9793 (Bf) (Vibration stabilization data) Infinity shooting state Maximum rotation angle (rad) 0.00611 of image stabilization lens group +0.128 (Position of positive image shift) The symbol indicates the same direction as the rotational movement direction of the lens.) (Condition corresponding value) f = 28.610 fF = -34.854 fL = 28.134 ΔWL = 0.0061 L = 6.7 f1 = -52.388 D = 12.7 (1) fLP / f = 0.718 (2) ΔWL = 0.00611 (3) f1 / fF = 1.503 (4) L / f = 0.234 (5) N- = 1.51680 (6) ν + = 57.58 (7) (R2 + R1) / (R2-R1) = -2.433 (8) D / fLP = 0.618 ( 9) PLP / PA = 5.443 (10) | fF | /fL=1.239 (11) fL / f = 0.983

FIG. 4 is a diagram of various aberrations of Example 2 in the infinity photographing state. In each aberration diagram, FNO is the F number, Y is the image height, and D is the d line (λ = 587.6 nm).
, G represents 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 3] FIG. 5 is a diagram showing a structure of a wide-angle lens according to a third embodiment of the present invention. The wide-angle lens shown in the figure is, in order from the object side, a positive meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, a negative meniscus lens with a convex surface facing the object side, a biconvex lens and a biconcave lens. A lens group G including a cemented lens with a plano-convex lens having a convex surface directed toward the object side, and a biconvex lens
F, a positive meniscus lens with a concave surface facing the object side, a cemented lens of a positive meniscus lens with a concave surface facing the object side and a biconcave lens, a positive meniscus lens with a convex surface facing the image side,
And a lens group GL composed of biconvex lenses.

The two lenses of the lens group GL arranged on the image side, that is, the positive meniscus lens having a convex surface directed toward the image side and the biconvex lens, constitute the antivibration lens group GLP. An aperture stop S is provided in the lens group GL. The anti-vibration lens group GLP is appropriately rotated and moved around the point P by the anti-vibration mechanism 1 which is a displacing means, and image shake caused by camera shake or the like is corrected. The third embodiment is applied to a wide-angle photographic lens having a shorter focal length than the first and second embodiments.

Table (3) below lists values of specifications of the third embodiment of the present invention. In Table (3), f is the focal length in the infinity shooting state, and FNO is the F in the infinity shooting state.
The number and Bf represent back focus. further,
The leftmost number is the order of the lens surfaces from the object side, r is the radius of curvature of each lens surface, d is the distance between the lens surfaces, and n is the distance between the lens surfaces.
(D) and ν are d lines (λ = 587.6 nm), respectively.
The refractive index and the Abbe number for n (G) are g-lines (λ
= 435.8 nm).

[0045]

[Table 3] f = 20.378 FNO = 2.80 rd ν n (D) n (G) 1 39.6230 5.6000 60.35 1.620410 1.633100 2 101.1760 0.1000 3 27.6070 1.4000 26.05 1.784700 1.824510 4 11.0354 4.0000 5 19.4100 1.2000 53.93 1.713000 1.729410 6 10.3299 3.8000 7 76.4200 3.2000 27.61 1.755200 1.791120 8 -30.0600 1.3000 49.45 1.772790 1.792320 9 11.9598 5.0000 35.70 1.625880 1.648550 10 ∞ 1.0000 11 32.9450 3.3000 32.17 1.672700 1.699910 12 -94.2301 1.6000 13 -90.0270 3.2000 46.42 1.582670 1.5987000 14 -1 Aperture S) 16 -22.8970 4.5000 49.45 1.772790 1.792320 17 -14.1510 1.1000 26.05 1.784700 1.824510 18 53.8430 0.8220 19 -79.4290 2.2000 60.35 1.620410 1.633100 20 -17.3650 0.1000 21 96.2190 2.8000 60.35 1.620410 1.633100 22 -31.2401 37.9654 (Bf) (vibration prevention) Long-distance shooting state Maximum rotation angle (rad) of anti-vibration lens group 0.00873 Image movement amount +0.254 (The positive sign of the image movement amount is the lens rotation (It indicates the same direction as the moving direction) (Condition corresponding value) f = 20.378 fF = -45.049 fL = 27.453 fLP = 18.652 ΔWL = 0.00873 L = 5.1 f1 =- 24.332 D = 15.922 (1) fLP / f = 0.915 (2) ΔWL = 0.00873 (3) f1 / fF = 0.540 (4) L / f = 0.250 (5) N -= 1.78470 (6) v + = 60.35 (7) (R2 + R1) / (R2-R1) = -2.3332 (8) D / fLP = 0.854 (9) PLP / PA = 6. 410 (10) | fF | /fL=1.641 (11) fL / f = 1.347

FIG. 6 is a diagram of various aberrations of Example 3 in the infinity imaging state. In each aberration diagram, FNO is the F number, Y is the image height, and D is the d line (λ = 587.6 nm).
, G represents 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.

[0047]

As described above, according to the present invention, it is possible to provide a retrofocus type wide-angle lens and an ultra-wide-angle lens which have a vibration-proof function and which are suitable for small size and high performance for photography and video. it can. Therefore, not only is it suitable for handheld shooting, but also slow shutter shooting and slow sync shooting are possible, which is extremely convenient during actual shooting. In addition, appropriate exposure according to shooting conditions is also possible. Further, if the anti-vibration lens group is displaced and fixed, it is possible to obtain a so-called tilt effect in which the perspective is changed.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a wide-angle lens according to Example 1 of the present invention.

FIG. 2 is a diagram of various types of aberration in the first embodiment at infinity imaging.

FIG. 3 is a diagram showing a configuration of a wide-angle lens according to Example 2 of the present invention.

FIG. 4 is a diagram of various types of aberration of the second example in an infinity imaging state.

FIG. 5 is a diagram showing a configuration of a wide-angle lens according to Example 3 of the present invention.

FIG. 6 is a diagram of various types of aberration in a third example of shooting at infinity.

[Explanation of symbols]

 GF Negative lens group GL Positive lens group GLP Anti-vibration lens group 1 Displacement means (anti-vibration mechanism) S Aperture diaphragm FS Fixed flare diaphragm P P Center of rotation of anti-vibration lens group

Claims (6)

[Claims] 1. A lens unit GF having a negative refractive power and a lens unit GL having a positive refractive power are provided in this order from the object side, and the back focus is longer than the focal length of the entire optical system and is positive as a whole. In the wide-angle lens having a refractive power of, a partial lens group GLP having a positive refractive power in the lens group GL has at least a positive meniscus lens having a convex surface facing the image side and a biconvex lens, Displacement means for rotating and moving the partial lens group GLP around a point on the optical axis, which is spaced a predetermined distance from the most image side surface of the partial lens group GLP toward the object side, is provided. When the focal length of the partial lens group GLP is fLP and the focal length of the entire lens system in the infinity shooting state is f, the condition of 0.3 <fLP / f <5.0 is satisfied. With anti-vibration function Wide-angle lens. 2. The lens group GF has a negative meniscus lens having a convex surface directed toward the object side, the partial lens group GLP is disposed closest to the image side of the lens group GL, and the partial lens group at the time of image stabilization Maximum rotation angle of GLP Δ
The wide-angle lens with a vibration isolation function according to claim 1, wherein WL (rad) satisfies a condition of ΔWL <0.1. 3. The focal length of the most object-side negative meniscus lens with the convex surface facing the object side in the lens group GF is f1.
When the focal length of the lens group GF is fF, the focal length of the entire lens system in the infinity shooting state is f, and the thickness of the partial lens group GLP along the optical axis is L, 0.2 The wide-angle lens with an anti-vibration function according to claim 1 or 2, which satisfies a condition of <f1 / fF <4.0 L / f <0.7. 4. The refractive index of the most object-side negative meniscus lens having a convex surface facing the object side in the lens group GF is N-, and the Abbe number of the most image-side biconvex lens in the lens group GL is ν 4. A wide-angle lens with an anti-vibration function according to claim 1, wherein the condition of 1.5 <N−40 <ν + is satisfied when +. 5. The radius of curvature of the most object-side surface of the most object-side positive meniscus lens in the partial lens group GLP is r1.
And the radius of curvature of the most image-side surface of the most object-side positive meniscus lens in the partial lens group GLP is r2, along the optical axis from the most image-side surface of the image stabilizing lens group GLP to the point. And the predetermined distance is D, and the partial lens group GLP
5. When the focal length of is fLP, the condition of -3.0 <(R2 + R1) / (R2-R1) <00 <D / fLP <10.0 is satisfied. A wide-angle lens provided with the image stabilizing function according to any one of items. 6. A fixed flare diaphragm is provided on the optical axis for blocking unnecessary light rays when the partial lens group GLP rotates and moves around the point for image stabilization. A wide-angle lens having a vibration isolation function according to any one of claims 1 to 5.