JPS58162922A - Zoom lens - Google Patents

Abstract

PURPOSE:To obtain a zoom lens having a large zooming ratio, by moving the first and the third lens groups, in a 4-group lens group provided in order with the first lens group of positive, the second lens group of negative, the third lens group of negative, and the fourth lens group of positive. CONSTITUTION:In a zoom lens constituted of 4 groups consisting of the first lens group 11 of positive, the second lens group 12 of negative, the third lens group 13 of negative, and the fourth lens group 14 of positive in order from an object side, in case of zooming to a telescope end from a wide angle end, the first lens group 11 moves linearly to the object side, and the third lens group moves non- linearly to an image face side.

Description

Detailed Description of the Invention The present invention provides a zoom lens suitable for still cameras, cine cameras, video cameras, etc., which has a large aperture, a large zoom ratio, is compact, and has a configuration that makes it easy to maintain manufacturing accuracy. It is related to.

Conventionally, this type of zoom lens Ti consists of four lens groups, and during zooming, the second lens group counting from the object side moves on the optical axis, and the magnification variable 1, 3, and 3 lens groups move on the optical axis. It is well known that the image plane position is corrected by moving the image plane. An example of these is the Special Publick Publication No. 39-6128.4I Kai-kai No. 39-13841. There are U8P2, 847, 907, etc.

As mentioned above, these are the fixed first
There is a lens group, followed by a second group with strong negative refractive power.
The lens group moves greatly on the optical axis to change the magnification, and the positive or negative third lens group moves on the optical axis to correct the change in focus position caused by changing the magnification. Image formation is performed by the fourth lens group. Maku, Tokko Sho 3
In 9-6128, the third lens group is fixed and the fourth lens group moves on the optical axis to correct changes in focus position, and the fifth lens group
Imaging is performed by a group of lenses. These conventional examples move a lens group with strong refractive power, so only a small amount of movement is required for zooming, which is advantageous for compactness. It has the disadvantage that it becomes difficult. In particular, if the refractive power is further increased for compactness, even stricter precision is required. This increases the number of movable groups and uses nine zoom lenses, for example,
The same applies to 149360.

An object of the present invention is to provide a compact zoom lens with a large aperture and a large zoom ratio.

A further object of the present invention is to provide a zoom lens that can maintain high manufacturing precision.

A further object of the present invention is to provide a zoom lens capable of correcting aberrations.

In the zoom lens according to the present invention, from the object side, a positive first lens group, a negative second lens group, a negative third lens group,
The fourth lens group is arranged sequentially and is composed of at least 44 lens groups, and when zooming, the @1 lens group and the third lens group are moved, and the second lens group with strong refractive power and The H4 lens group is fixed. By moving the first lens group, the IX2 lens group is given a variable power effect.

C. In the zoom lens according to the present invention, in order to have a large variable power effect in the second lens group and to have a compact structure despite the large zoom ratio, the second lens group is
It is desirable that the imaging magnification of the lens group changes within a region including equal magnification (-1).

Hereinafter, the present invention will be explained in detail using drawing F1.

Table J1 shows the paraxial arrangement of the GL embodiment of the zoom lens according to the present invention, and FIG. 1 shows mtth* of the zoom lens shown in Table 1.

In Table 1, fi is the focal point distance of the first lens group -1eHId, and the distance between the principal points between the i-th lens group and the gs+x lens group, and β is the imaging magnification of the fifth lens group. The zoom lenses shown in Table 1 are listed in order of IO from the object side! S/Z group 11. Negative 01
1E2vys group 12. This is a zoom lens composed of four groups: a negative TA3 lens group 13 and a positive 814 lens group 14. As shown in the first WJK, if the lens group 11 and the third lens group 13 each move in nine different trajectories. Zoom from K. That is, during zooming from the wide-angle end to the telephoto end, the second lens group 12 plays the role of zooming by moving linearly toward the object side.
The third lens group Fi moves non-linearly toward the surface side and plays a role in correcting the side surface.

The AT lens group 11 has positive power, which is necessary to achieve a compact zoom lens with a large aperture. In other words, by converging the luminous flux in the first lens group, the height of the luminous flux entering the second lens group and thereafter can be lowered, thereby making it possible to reduce the lens diameter of the second and subsequent lens groups, as well as correcting aberrations. It facilitates In order to provide the second lens group 12 with 4tllt power, it is necessary to provide KFi and the second lens group with strong negative power. In particular, it is preferable that the imaging magnification of the fixed fX2 lens group, which changes with the movement of the 1st lens group, changes in a region including equal magnification. By setting the refractive power of the H3 lens group 13 to be negative, the range in which the refractive power exists, which is actually subject to self-surface correction, becomes wider, and it is possible to set a weak refractive power. Therefore, the configuration of the third lens group can be simplified, and am can be corrected with a small amount of movement. The fourth lens group 14 performs integration of all lens systems.

In this case, the functions can be divided such that the variable power function is performed by the 3rd lens group to the 3rd lens group, and the variable power is performed by the 4th lens group. This has the advantage that it can be corrected by the lens system, and aberration components not related to zooming can be corrected by the fourth lens group. Table 2 is data showing an example of nine cases in which the paraxial arrangement shown in Table 1 is thickened. Figure 2 shows the lens cross section at the intermediate focal length of the zoom lens shown in Table 2, and Figure 3 shows the various aberrations at each zoom position.
6) Shown at 00. Note that 0 is the wide-angle end, (b) is the intermediate focal length, and 0 is the telephoto end. ΔMFi is the meridional plane of astigmatism, and ΔS is the sagittal plane. In Table 2, F is the pointless distance of the entire system, FNo is the F number, 2- is the angle of view, i is the radius of curvature of the i-th lens surface counting from the object side, and D
i is the axial wall thickness or axial air gap between the i-th surface and the 1+1-th surface counting from the object side, NI is the refractive index of the 111rth lens from the object side, and νi is the Atsube number. be.

Table 2 F Otori 1.00-5.74 Shi1M-1: 1.4-10
2ω-53,1~10.0R1-8,133D
I= 0.18 N 1-1.8466@y
1-23.9R2 leak 4.027 D Akebono 1.00 N 2-160311 ν
Goose ■6α7R3--14,226D 3-0.011t
4- 2.968 1) 4- 0!55
N 3-1.60!111, 5-60.
7Ra-6,486D 6-Variable R6-49,106D ・-α10 N 4 Self 1
sssoo ν 4 40.8R7 0. ! j
46 +) 7■ 049R8--4,162D
I-0,10N S-1,63854ν S-5
N4H9-Q, 838 D 9- 0.36
N 6-1.75520 y l5-27.
1RIO--7,394DIG-variable all--1453Dll-0,10N? -1.6
9350y't-8L2R12--1211
so D12 Kirimachihen R13-13,214DIm-0
,45N 8-1.69610, 1-15z
R14 -2,574Di4-0.02R15 votes
2298 Dlg bite 0.45N9 bird 1.6031
1 ν 9■6α7R16-15,574Dlg
−α22R17−−2,202D17=0.12
Nl0-1.84666 ylo-43 meeting 1L
18- 50.010 Di8 Shizuku 0. G281G
-3,359Di9- O45N11-1.696J
IO, 11-55, 51L20- -3.311
D2G-α32R21-1,315O21-α12
N22-1.805111 yl Tomi-Goose 5.4B
! 2-〇,921 O22-0,32iL2B
-1,742O23-0,32N13-169680
．． 1m-15,l5B24- 3.968 O24
-Variable M21=0.0 D25=0
．． 55 N14-1.51633 y14-6
4.11126 layers 00 Table 3 shows the paraxial arrangement of the second embodiment of the zoom lens L/'/Z according to the present invention, and FIG. 4 shows the movement of the zoom lens shown in this $3 table. The trajectory is shown.

Table 3 'l*Jeβi Fi Since it is the same as Table 1, the explanation will be omitted. -The zoom lens shown in Table 3 is 11@ from the object side.
VC1 positive 24 lun group 11. negative second lens group 12;
It is composed of the ik third lens group 13, the negative IE4 lens group 14, and the positive fifth lens group 15. During zooming, m<, @t lens group l11 third lens group shown in FIG.
Lens group 13 and fifth lens group 15 move. When zooming from the wide-angle end to telephoto, the lens group and the fifth lens group play the role of changing magnification by moving linearly toward the object side, while the third lens group moves non-linearly. By doing so, it plays the role of correcting the position of my surface. The operational effects of the 11°+12 lens group 12 and the third lens group 13 are the same as in the first embodiment. As a lever, a fixed group with negative refractive power is arranged in the @4 lens group 14 to have the function of increasing the variable power by moving the fifth lens group. As a result, the variable power can be appropriately shared between the second lens group and the fifth lens group, resulting in a zoom lens that is easy to manufacture.

Table 1g4 is lens data showing an example of a case where the paraxial arrangement shown in Table 3 is changed to inner thickness. Figure 5 shows a cross-section of the zoom lens shown in Table 4 at an intermediate focal length, and a diagram of various aberrations at each zoom position! Figure 6 <AJ @
(See Q. Note that (6) is the wide-angle end, what is the intermediate focal length,
0 is the telephoto end.

4th Table F-10e~119 FNO-1:14~! 02m-1
11-15BZIS-Q, OD2g-0,55N11-
1.51613yt device-641B9-a.

1. The zoom lens according to the present invention has a configuration of four or more lens groups having three positive, negative and negative lens groups in order from the object. By fixing #, it is possible to realize a compact, high-magnification zoom lens with better construction properties than VC.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the movement locus of the zoom lens according to the first embodiment of the present invention, FIG. 0 represents each zoom position/of the zoom lens shown in FIG.
FIG. 4 is a diagram showing the movement trajectory of 42 embodiments of the zoom lens according to the present invention, and FIG.
A diagram showing a cross section of the zoom lens of the embodiment with a thicker wall. FIG. 6 (6) (b) 0 is a diagram showing various aberrations at each zoom position of the zoom lens shown in FIG. . 11... 1st lens group, 12...@22 lens, 13
...Third lens group, 14...Fourth lens group, 15.
... 53rd lens group, constraint... radius of curvature of i-th surface, Di
...The axial air gap or the axial wall thickness between the first surface and the 1st+1 surface. Output Canon Co., Ltd.

Claims (3)

[Claims] (1) At least the positive luns # in order from the object side.
, a negative second lens group, and a negative third lens group. A zoom lens comprising a fourth lens group, wherein during zooming, the first lens group and the third lens group move, and the JIE2 lens group and the fourth lens group are fixed. (2) The zoom lens according to claim 1, wherein the movement loci of each lens group that moves during zooming are different. (3) The zoom lens according to claim 11, further comprising a lens group movable during zooming, the fourth lens group having a surface l4IK.