JPS60170817A - Zoom lens with wide view angle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zoom lens with a wide angle of view, and particularly to a zoom lens suitable for still cameras, cine cameras, video cameras, and TV right cameras.

Conventional zoom lenses with wide angles of view include so-called two-group zoom lenses, which have two lens groups with negative and positive refractive powers in order from the object side, and change the distance between both lens groups to change the magnification. Various proposals have been made. However, although a two-group zoom lens is advantageous in achieving a wide angle of view, it is difficult to obtain a high variable power ratio, and the variable power ratio is approximately 2 times at most.

On the other hand, various zoom lenses have been proposed that have a wide angle of view and achieve high variable power by moving three or more lens groups.

For example, Japanese Unexamined Patent Publication No. 154205/1983 has five lens groups, the first lens group counting from the object side. The third and fifth lens groups are integrally moved toward the object side, and the second lens group is moved toward the image plane side to perform zooming.

Furthermore, Japanese Patent Application Laid-Open No. 57-164709 has five lens groups, and the third. The zooming is performed by moving the fifth lens group integrally toward the object side, the lens group toward the object side, and the second lens group toward the image plane side.

However, all of these proposed zoom lenses have a long overall lens length, and the movement state of each lens group is complicated, so that the lens barrel structure tends to be complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wide-angle zoom lens that is compact and has excellent aberration correction.

The main features of the zoom lens for achieving the object of the present invention are positive, negative, positive, positive, and positive refractive powers in order from the object side. Second. Third. It has five lens groups, a fourth and a fifth lens group, and the first and seventh lens groups and the fourth lens group are integrally moved toward the object side, and the third lens group and the fifth lens group are integrally moved toward the object side. Changing the magnification from a wide-angle end to a telephoto end by moving the second lens group toward the object side and toward the image plane side, respectively;
Said 3rd. 4th. The focal length of the fifth lens group is fB.
z /4 + 711, and the focal length of the entire system at the wide-angle end zoom position is to satisfy the following conditions.

FIG. 1 is an explanatory diagram showing the movement state of each lens group due to zooming of the wide-angle zoom lens of the present invention.

In the present invention, there are five lens groups as shown in FIG.
By forming a group of three movable groups as a whole, the lens barrel structure is simplified and a compact zoom lens with a wide angle of view and high zoom ratio is achieved.

In particular, zooming is performed by moving the second lens group toward the image plane, but at this time, the combination lens group A, which integrates the first and fourth lens groups, is moved toward the object side and the second lens group A high zoom ratio is achieved by promoting the zoom ratio effect. And WJ3
When the lens group is moved toward the object side, the curvature of field becomes about 1 overcorrected due to the refractive power arrangement when zooming from the wide-angle end to the telephoto end zoom position. Therefore, in the present invention, the fourth lens group is moved toward the object side to compensate for the field curvature.

The fourth lens group is the first lens group on the object side. Second. It moves so as to correct the positive distortion generated from the third lens group in the negative direction. The astigmatism caused by the movement of the fourth lens group is corrected by moving the fifth lens group.

Also, a combination lens group B that integrates the third and fifth lens groups
By moving the lens toward the object side during zooming, aberration fluctuations due to zooming are corrected, the refractive power of all lens groups is appropriately arranged, and the entire lens system is made more compact.

Next, each conditional expression will be explained.

Conditional expression (1) limits the refractive power of the third lens group; if the upper limit is exceeded and the refractive power weakens, the amount of movement during zooming must be increased, making the zoom lens more compact. Moreover, if the refractive power becomes strong beyond the lower limit, there will be many aberration fluctuations due to zooming, and it will be particularly difficult to correct field curvature.

Conditional expression (2) is intended to integrate the third lens group and the fifth lens group and move them toward the object side to better correct aberration fluctuations during zooming.If the upper limit is exceeded, the fifth lens group The refractive power is smaller than the third lens group υ, and it is difficult to properly correct aberration fluctuations when changing the magnification by moving the unit together, and if the lower limit is exceeded, the refractive power of the third lens group If the aberration is too strong, high-order aberrations will occur during zooming, and it will be difficult to correct them.

Conditional expression (3) limits the balance of refractive power between the fourth lens group and the fifth lens group, and if the upper limit is exceeded and the refractive power of the fourth lens group becomes weaker than that of the fifth lens group, it will be difficult to change the power when changing the magnification. It becomes difficult to make the last zoom lens compact because it requires a large amount of movement, and if the refractive power of the fourth lens group becomes strong beyond the lower limit, there will be a lot of aberration fluctuation when it moves integrally with the fourth lens group. I don't like it.

Although the object of the present invention can be achieved with the above lens configuration, it is more preferable to satisfy the condition that the focal lengths of the first lens group and the second lens group are each 'ly'2.

If the upper limits of conditional expressions (4) and (5) are exceeded, the refractive power of the front lens group of the zoom lens will become relatively weak, the telephoto type will deteriorate, and the total length of the lens will be long. (
If the lower limit of 51 is exceeded, the refractive power of the front lens 711'' will be too strong, making it difficult to obtain a predetermined back focus.

In addition, in the present invention, it is necessary to correct aberration fluctuations during zooming.In order to achieve good aberration correction, a laminated lens in which lenses with negative and positive refractive powers are laminated in order from the object side is used. The second lens group is a meniscus-shaped lens with positive refractive power with the convex surface facing the object side, and the second lens group is a lens with negative, positive, negative and positive refractive powers, and the third lens group is a lens with positive and negative refractive powers. The fourth lens group consists of a laminated lens in which both lens surfaces are convex, a lens in which both lens surfaces are convex, a lens in which both lens surfaces are concave, and a lens in which lenses with positive and negative refractive powers are laminated together. It is preferable that the fifth lens group is composed of a laminated lens in which lenses having positive and negative refractive powers are laminated together.

In the present invention, focusing is performed repeatedly throughout the lens system.
Of course, the first thing is to bring it out and do it. The fourth lens group or the third lens group. The fifth lens group may be extended out. Alternatively, only the second lens group may be moved.

As described above, according to the present invention, it is possible to achieve a compact, high-power zoom lens with little variation in aberrations during zooming.

Next, numerical examples of the present invention will be shown. In the numerical example °, Ri is the radius of curvature of the first lens surface from the object side, Di is the thickness and air gap of the first lens from the object side,
N and ν are the refractive index and the temperature of the glass of the υIPKiith lens from the object 1 1 side, respectively.

Numerical Example 1 F-35,52-104,4FNO-1:3.5-4.
5 2w-6SL7"-23,4'R+-10Z70
Dl-2,,02N+-1,80518sit-25.4
R2-57,990,-8,06N,-1,62299
C, -5 & 2R, -363.03 D, -0,20 R, wGo, 96 D4-6.05 N3-16968
0 1'3-ss, sR, -21L30 D, -733
Variant R6-250, 26D6-t, 12 N, -1,816
00ν4-46.6R? -17,5007-6,13 R,--159,28D,-λ15 Nl+-1805
18J, -25.4J-=34.63 0. -1.12
N6-1.81600 Jiro 46.6 to o-178
,64~-0,19 R,,-24,32Dll-134Ny-1,8051
8y, -2a4l Export -34,27DIt-Variable [-3-Aperture Re DI, -1,67 R,, -3a98 Q4-5.02 Jl, -1622
99y@-5&2R11+--2Z33 Dllll-1
,12Ng-1,80518yo-25-4 rep,--4
121D,, -0,22R,, -25,48D,, -3,35N,. -1,69
680ν,. -55,5 reps,--17169D,,-1
,50 R,,--61,77D,,-1,00NB-1,78
590shi, -442R2o-26,84D! l0-L
OO Bird 1- 69.05 02. -3.00 n, 2-i,
5osxs y12-25.4RIIx--32,,7
7 Ning 2-1.30 N, 3-1.81600 Si 13-
4a6 Bird, -33.41 Hemorrhoid, -Variable R24--179,12Dl4-7.50 N14-i
, 7iaoo y14-5&8~--1a51~-L
OON,ll-1,80528shi16-25.4-0-
-37.04 Doll-Variable R27-96,910,1-6,00N,6-1.62
230 ν16-53L2%s--60,580,s-
1,50Nl7-1.77250 17-49.6, -187.93 Numerical Example 2 F-35,41~104.01 FNO-1:3.5~
4.52w-62,8°-23,5'R,-1OSL3
1 D, -102N, -1,80518shi 1-25.4
R, -57,5602-N06 N, -1,62299
Sheer 5&2R8 Kabura 409.15 D, -0,20 R4-6&44 D4”6.05 Ng-1,6968
0Sig-55.5R5-231,01Dll-HaR6-296,80Doll, 12N, -1,816
00ν, -46,6R, -17,450, -6,13 R, -16419D, -215N, -1,80518
νll-25,4R@--34,65DB-1,12N
6=1.81600 v6-46.6R1°-183,
86D, o-0, 19R,, -J4.30 D,, -2
,34N1-1.80518y,-25,4R1,~
34.53 Dl, -Variable R13-Aperture 1, -1,54 Tow, x 33.25 D, -6,00 to 8-1.62
299 shi, -5 & 2 rep, +w -20,94 crow s-1
,03~9-1.80518 ν, -25,4kawa,-
-38,64DI6-0.21 R,7-23,47DI7-3.09 N,O-1,6
9680shiIo-55.5 Karasu, --159.40 Hanawa,
-i, a sR,, -56,26D,, -0,92
N, -L78590 Shi, 1-442iQ-24,78
1), o-1,85 R2,-66,65DB□-277N+2-1.805
18 ν12-25.4R22--30,23 included 2-1
．． 20 N, 3-1.81600 C1. -46.6R
13-31, 10D2s-variable hook. --176,80 crows. -9,00 to -1,713
00ν,, -53811,5--16,224,-0
, 99, -1,80518,, -25.41. −
-36,74 sound 6-variable bird, +100.30 hemorrhoids 7-6.24 be, -1,6
2230ν1. e-5:12--63,68I),
8-1.56 N,, -1,77250shi1□-49.
649--19&23 Numerical Example 3 F-35,21~104.16 FNO-1: 3°5~
4.5 2 w-63, f ~ 23.5°R, -1O1L
85 Dl-Z02 N1-1.80518 C, -2
5.4R, -57, 55D, 406 N2-1.622
99 ν, -58,213-370,73D, -0,2
0 R4-63,49D4=6.05 Nrl, 69680
W 3-55.5R, -249, 22D, -variable R6-34 & 41 D, 1.12 ~ 4-181600
$', -46.6 R7 hit 17.32 D, -6,1
3 RB--169, 27DB-115, N, -18051
8y6-25.4Rge-34,66D, -1,12N,
Depression 1.81600 to Jiro 40.6. -187,39
D. -0,19 R,, -24,33DI, -2-34N, -18051
8ν, -25, 4birds t-35, 07DIt-variable Iζ, -Aya) Tiger-L43 RI4- 31.16 0. , -6.00 NB”1.
62299 1J-sazR,,--19,32D,,
-0,95N, -1,80518ν. -25,4I%1
5--36.27 D, -0,191%, -21,8
3D, 7-3.00 N,. -1,69680shi, o-
55.5R,,--147.14 0. , -1.501
~. --51,75DI9-0.85 Nll-1,7
8590Nll-44,2R2o-2SL78 D.

-2,00R1! I-61,78Dzl-180N+2
-1.80518 C12-25.4R2, --z7.
9o D22-1. tt N,, -1,81600shi,
, -46.6~. ~28.17 D2. -Variable R2,--173,54D! 4-9.00 N, 4-1
．． 71300 y, 4-53.8 bird sl+ -16,0
0 sound 5”0.98 N, 5-1.80518”+5-
25.482, --36.25 D2 variable R? 7 Mai 10465 sound, -6,49N,, -1,6
2230 Shu6-5λ21, --66,16D2. −
1.62 N, -1,77250ν, -49,6 birds, -1204.96

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the movement state of each lens group due to zooming of the wide angle of view zoom lens of the present invention, Fig. 2 is a cross-sectional view of the lens of Numerical Example 1 of the present invention, Fig. 3 (5) -(C), FIGS. 4(A)-(C), and FIGS. 5(5)-(C) are various aberration diagrams of Numerical Examples 1 and 2.3 of the present invention, respectively. In the diagram, x, x
, m, ■, v are the first degree, second degree, and second degree, respectively. Third. 4th. The fifth lens group, the arrow indicates the moving direction due to zooming, ΔM indicates the meridional image plane, ΔS indicates the sagittal original, and S and C indicate the sine condition. 1st M Boiled 2I ¥1 u+to, f' Sen III Tsukimatae (9)

Claims (1)

[Claims] (11) It has five lens groups: 1st, 2nd, 3rd, 4th and 5th lens groups with positive, negative, positive, positive and positive refractive powers in order from the object side, 'Ah Note 4 i Move the lens group and the fourth lens group integrally toward the object side, move the third lens group and fifth lens group integrally toward the object side, and move the second lens group toward the image plane side. The focal length of the 3rd, 4th, and 5th lens groups is set to 'S + 74 + 16, respectively, and the focal length of the entire system at the wide-angle end zoom position is changed by zooming from the wide-angle end to the telephoto end. A wide-angle zoom lens that satisfies the conditions when the distance is /W. (2) The first and fourth lens groups and the third and fifth lens groups are connected linearly, 2. The wide angle of view zoom lens according to claim 1, wherein the second lens group is moved non-linearly to change the magnification.