JPS63133119A - Photographing lens with oscillation-proof function - Google Patents

Abstract

PURPOSE:To shorten the lens diameter of a correcting lens group and to improve the responsiveness for oscillation prevention by arranging the correcting lens group nearer to the image surface side than a focusing lens group. CONSTITUTION:A lens system consists of four lens groups, namely, the first fixed lens group I, a focusing lens group F moved on the optical axis, the second fixed lens group II, and a correcting lens group C which is moved in parallel or is inclined to be off-center for the purpose of correcting blur of a picture. The lens group F other than the first lens group I on the object side is moved to focus the image. In this case, the correcting lens group C is arranged nearer to the image surface side than the focusing lens group F. Thus, the lens diameter of the correcting lens group C is shortened and the weight of this group C is reduced, and extension of a lens barrel is prevented, and the burden on a driving system of the correcting lens group C is reduced, and the responsiveness for oscillation prevention is improved.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a photographic lens having a function of correcting blurring of a photographed image due to vibration, a so-called anti-removal function. In a shooting system that uses an internal focusing method in which one lens group other than the lens group is moved along the optical axis by two inches, the correction lens group for image stabilization is made smaller and lighter, and the correction lens group is decentered. The present invention relates to a photographic lens having an anti-vibration function that prevents deterioration of optical performance due to focusing when the anti-vibration effect is exerted, and improves controllability of an actuator.

(Prior Art) When attempting to photograph a moving object such as a moving car or aircraft, vibrations are transmitted to the photographing system, causing blur in the photographed image. The blur in the photographed image at this time increases as the focal length of the photographing system increases.

Anti-vibration optical systems having a function of preventing blur in photographed images have been proposed in Japanese Patent Publication No. 5FI-34847, Japanese Patent Publication No. 74111-1982, Japanese Patent Publication No. 7416-1987, and the like.

In these publications, an optical member that is spatially fixed against vibrations is arranged in a part of the imaging system, and by utilizing the prism effect produced by this optical member against vibrations, the photographed image is deflected and the imaging plane is A still image is obtained above.

In addition, a ship speed sensor is used to detect vibrations in the photographing system, and at this time (a), a still image is generated by vibrating some of the lens groups in the photographing system in a direction perpendicular to the optical axis. There is a way to get it.

There is also a method in which the movement of a captured image formed on an image sensor such as a CCD is analyzed through electrical processing, and the signals obtained at this time are used to obtain a still image.

Generally, when a part of the correction lens group in the photographing system is decentered to eliminate blur in the photographed image, and to obtain a still image, it is required that the amount of eccentric aberration generated when the correction lens group is decentered is small. It will be done. In addition, the amount of decentering aberration generated at this time needs to be small not only at the reference object distance but also at all object distances, from objects at infinity to objects at close distances.

As mentioned above, blur in photographed images often occurs in long focal length telephoto lenses, and for this reason, there is a strong demand for telephoto lenses to have an anti-shake function. In addition, telephoto lenses use a so-called internal focusing method in which focusing is achieved by moving a compact, lightweight lens group with a relatively small diameter on the image plane, other than the object-side lens group, on the optical axis. There are many cases.

Generally, in a telephoto lens that uses such an internal focusing method, if some of the lens groups are decentered to perform image stabilization, the amount of decentration aberrations will significantly increase, especially when focusing. This increases the variation in the amount of core aberration, which causes a significant deterioration in the optical performance of photographed images.

In addition, the anti-vibration mechanism attached to the photographic lens is required to have good response. For this reason, it is desired to make the movable lens group as small and lightweight as possible, and to use a lens group with a small inertial mass as the correction lens group.

(Problems to be Solved by the Invention) The present invention reduces eccentric aberrations that occur when correcting blur in a photographed image by decentering the correction lens group in a photographing lens using an internal focusing method. The purpose of the present invention is to provide a photographic lens having high optical performance with little decentering aberration occurring especially when the object distance is changed by focusing, and also having an anti-vibration function with good responsiveness during anti-vibration.

(Means for solving the problem) It has a plurality of lens groups, of which at least one lens group F located behind the object side lens group is moved in the optical axis direction to perform focusing and the lens. The lens group C, which is arranged closer to the image plane than the group F, is decentered to correct blur in the photographed image.

(Example) FIG. 1 is a sectional view of a lens according to Numerical Example 1 of the present invention.

In the figure, F is the first fixed lens group, F is the focusing lens group that moves on the optical axis, +1 is the second fixed lens group, and C is the lens group that is parallelly moved or tilted to correct blurring of the photographed image. This is a correction lens group that decenters the center of the lens. In this embodiment, a telephoto lens with a long focal length is constructed from the four lens groups having the above functions, and focusing is performed by moving one lens group F other than the lens group on the object side. It has a traditional focusing method.

In this embodiment, by adopting a lens configuration in which the correction lens group C for correcting blur in the photographed image is placed closer to the image plane than the focusing lens group F, the correction lens group C
The aim is to reduce the lens diameter and weight. This prevents the lens barrel from increasing in size, reduces the burden on the drive system for driving the correction lens group C, and improves responsiveness during image stabilization.

It also reduces the amount of decentering aberration that occurs when the correction lens group C is decentered, and reduces the amount of variation in decentering aberration that occurs with changes in object distance, which often occurs especially when using the internal focusing method. ing.

Furthermore, the movement of the image due to the eccentricity of the correction lens C when correcting the blurring of the photographed image is prevented from changing with respect to the change in object distance, that is, the focus.

This prevents deterioration in optical performance and also simplifies the decentering mechanism used to decenter the correction lens group C.

Further, in this embodiment, the ratio of the amount of movement of the correction lens group C to the amount of movement of the photographed image is always constant, thereby simplifying the correction control for blurring of the photographed image.

Next, using the lens system shown in Figure 7 as an example of a general lens system, we will explain the aberration theory regarding the occurrence of eccentric aberration when correcting blurring of photographed images by decentering some of the lens groups in the lens system. From my standpoint, I will explain based on the method presented from well logging at the 23rd Applied Physics Conference (1962).

In the figure, A is the first fixed lens group, C is the correction lens group that is decentered to correct blur in the photographed image, and D is the second fixed lens group.
This is a fixed lens group.

The amount of aberration ΔY of the entire system when some lens groups of the photographic lens are parallel decentered by E is the amount of aberration ΔY before eccentricity and the amount of decentering aberration caused by eccentricity, as shown in equation (a). ΔY (E
). Here, eccentric aberration ΔY (E) is (b)
As shown in the formula, first-order eccentric comatic aberration (IIE), first-order eccentric astigmatism (■E), first-order eccentric field curvature (PE), 1
Next eccentric distortion aberration (VAN), first-order eccentric distortion additional aberration (VF6), and first-order origin shift (ΔE) are expressed. Here, the aforementioned various aberrations (II E), (m E)
, (PE), and (ΔE) are the incident angle and exit angle of the light beam to the correction lens group C, respectively. , ToThe incident angle and exit angle of the light ray to the second fixed lens group are α4 and r, respectively, and the aberration coefficient of the correction lens group C is calculated. , H,, mc, PC, V, aberration coefficient Ia of fixed second lens group, TId, 1II
Using d, Pd, and Vd, it can be expressed as in equations (C) to (f).

Δ'Y=ΔY+ΔY (E) (
a) 10Z l (N, ttu + hood sweat 1 cs (1'J,
-$, ) f cs('l=,,-t-$,)) (
x E) + csf, co4ct+, (PE)'J ten (gnruw clean Z+Cts-e2f,,) (Vε+)+
(VEz')) (TIE) = αdl+, +-αc
(n, +rrd)-πd d+positive, (■.+Ia)
(c) (II[E) = αdllTd−α
c (m c + m d)-Hand"" C1,,
(II c”ll a) (d) (PE)=
αdPd−αc(P,+P a) (
e) (ΔE) = -2 (α, -αゎ) (f) Equations (C) to (f) regarding decentering aberrations are the paraxial amounts related to the fixed second lens group and correction lens group C, and these It is expressed as a polynomial of the shared aberration of the lens group.

As is clear from equations (C) to (f), even if correction is made to reduce the amount of eccentric aberration generated at the reference object distance, the object distance changes, and in this case, the fixed second lens group and the correction lens If the aberration coefficients related to group C change, eccentric aberrations may increase.

In particular, when focusing is performed using a fixed second lens group or a fixed correction lens group, the aberration coefficients of these lens groups change, and eccentric aberration changes as the object distance changes.

For this reason, in this embodiment, as shown in FIG.
By arranging the lens group F closer to the image plane than the focusing lens group F, the amount of decentering aberration that occurs when the object distance changes when using the internal focusing method is reduced.

In particular, in this embodiment, the amount of eccentric aberration generated when focusing on a near-axis object is reduced.

Among equations (C) to (f), equation (f) relates to the movement (2) of the photographed image on the image plane when the correction lens group is moved by a predetermined amount in a direction perpendicular to the optical axis.

As is clear from equation (f), if each lens group is configured as in this embodiment, the ratio between the amount of movement of the correction lens group and the amount of movement of the photographed image can be kept constant, and the decentering mechanism can be simplified. This makes it easier to

In this embodiment, in order to further reduce the amount of decentering aberration that occurs during focusing and when correcting blur in photographed images, at least one lens group F, a fixed second lens group II, and a correction lens group C are used. It is preferable to configure the lens to have a positive lens and at least one negative lens.

In this embodiment, various types of lens configurations other than the lens configuration shown in FIG. 1 may be used as long as the correction lens group C is arranged closer to the image plane than the focusing lens group F. can.

For example, as shown in FIG. 4, a third fixed lens group m may be arranged on the image plane side of the correction lens group C of the lens system shown in FIG. Fixed lens group II
may be omitted and the lens group may be composed of three lens groups 1, F, and C. Further, the object of the present invention can also be achieved with a lens configuration in which the second fixed lens group H is disposed on the image plane side of the correction lens group C of the lens system shown in FIG.

Furthermore, the object of the present invention can be achieved even in a lens system in which at least two focusing lens groups are provided on the object side of the correction lens group C, and focusing is performed by moving the plurality of lens groups at different speeds. be able to.

Next, a numerical example of the embodiment shown in FIG. 1 will be shown. In the numerical example, R1 is the radius of curvature of the first lens surface from the object side, Dl is the thickness and air gap of the first lens from the object side, and Ni and ν1 are the first lens surface from the object side. are the refractive index and Atsube number of the glass. Nl01
ν10, N15, and υ15 are values related to silicone oil.

Numerical example F-300FNo-]・2.82ω-
825°R]=121.99 DI=1
6.81 N ]=1.43387 ν ]
=95. ]R2=-574,68D2=1
．． 22R3=119.61 D3=16
．． 30 N 2=1.49700 ν 2=
81.6R4=-432,30D 4=4.
21R5=-:]]6.01 D5=
5.60 N 3-1.72047 v
3=3C7R6= 278.39 D B=
3], 90R7-45,9007=6.11
N 4-1.589]3 ν 4-[il, OR
8=40.75D 8-17.40R
9=-250,63D 9=6.11
N 5-1.80518 ν 5=25.4R]
O=-75,58DI0□ 2.55 N
6-1.6+340 v 6=43.8R1
1.92.58 Dll=34.16R]2
= 285.03 DI2 = 5.40
N 7=], 74950 ν 7=35.3R
]3=-116,05Dl3=2.55
N 8=], 6204] ν B-60,3R]
4=82.72 DI4=9.17R]5
= co Dl5=2.55 N
9J, 5] 633 v 9-64. IR]6=
oo Dl6- 0.04 Nl
0=1.40590v]0=52.0RI7-
■ Dl7-3.97 N11=1.
47069 ν]1=67.4R18--284,
24Dl8-0.51R]9-76.73
019・7.58 N12=1. [11720shi12=511.01120--115.26 D2
0. 2.55 N15=], 805] 8 Shi13-25.4R21-■ 021.14.27
R22=O:) D22=2.
55 N14-1.5+633 v 14=6
4. ]R23= (X) D23-
0.04 N+5=1.40590 v ]5
=52.0R24-oo D24=4.5
9 Nl6=1.51633 v 16=6
4.1R25=ω (Effect of the invention) According to the present invention, by adopting a lens configuration in which a correction lens group is arranged closer to the image plane than a focusing lens group in a photographing lens using an internal focusing method, The lens diameter of the correction lens group has been reduced to improve responsiveness during image stabilization.In addition, the correction lens group has been decentered at all object distances, from objects at infinity to objects at close distances, to improve image quality. It is possible to achieve a photographic lens having a vibration-proofing function and high optical performance with a small amount of decentering aberration when correcting blurring.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a lens in a numerical embodiment of the present invention, Fig. 2 is an aberration diagram for an object at infinity in a numerical embodiment, and Fig. 3 is a numerical embodiment in which the correction lens group is oriented perpendicular to the optical axis. 2mm
Aberration diagrams when moving; Figures 4, 5, and 6 are schematic diagrams of lens configurations of other embodiments of the present invention; Figure 7 is a lens configuration for explaining eccentric aberration in the present invention. FIG. In the figure, ■, II, and ■ are the first, second, and third, respectively.
C is a correction lens group, F is a focusing lens group, 6M is a meridional image plane, ΔS is a sagittal image plane, d is a d-line, and g is a g-line. Patent Applicant Canon Co., Ltd. Yoshi 2 Concave (A) Procedural Amendment (Toge) April 3, 1986 Commissioner of the Patent Office Mr. 2 Title of Invention Photographic lens with anti-vibration function 3 Case of person making correction Relationship Patent applicant address 3-3C1-2, Shimomaruko, Ota-ku, Tokyo Name (1
00) Canon Co., Ltd. Representative Ryu Kaku
3 Part 4, Agent's residence Address: 301 Jiyugaoka, Belheim, 2-17-3 Okusawa, Setagaya-ku, Tokyo 158 (Telephone 7] 8-5614) (1
) Drawing 6 attached to the application, contents of amendment (1) Figure 7 is amended as shown in the attached sheet. Page 7 Proceedings (self-proposal) l, Indication of the case 1985 Patent Application No. 282371 2, Name of the invention Photographic lens with anti-vibration function 3, person making correction Relationship with the case Patent applicant Address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (100
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4, Agent's residence: 2-17-3 (1) Okusawa, Setagaya-ku, Tokyo 158
Column 6 of detailed explanation of the invention in the specification, content of amendment (X) (() Formula % from line 9 to line 12 on page 8 of the specification (% formula %))

Claims (1)

[Claims] (1) It has a plurality of lens groups, of which at least one lens group F located behind the first lens group on the object side is moved in the optical axis direction to perform focusing, and the image plane is lower than the lens group F. A photographic lens having an anti-vibration function, characterized in that blur in a captured image is corrected by decentering a lens group C disposed on the side.