JPS60419A - Telephoto zoom lens - Google Patents

Abstract

PURPOSE:To correct satisfactorily various aberrations extending over the whole displacement area of zooming by constituting so that an optical system consisting of three lens groups having refractive powers of positive, negative and positive in order from an object side satisfies prescribed conditions. CONSTITUTION:A relay lens system consists of a front group containing positive and negative lens components, and a rear group containing negative convex meniscus and positive biconvex lens components at an image side, and the first group contains two positive lens components and one is a stuck component, the second group contains two negative components and one is a stuck component, and the third group contains at least one positive lens component. This optical system is made to satisfy each condition of an expression I - an expression IV. In this regard, in the expressions, fR denotes a composite focal distance of the relay lens system, ra, rb denote radiuses of curvature of surfaces of an object side and an image side of a negative meniscus lens which is convex to the image side of the rear group of the relay lens system, f1, f2 denote focal distances of the first and the second groups, respectively and rc, rd denote radiuses of curvature of surfaces of the object side and the image side of the negative lens component of the object side of the second group, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a telephoto zoom lens, in particular a variable power system consisting of a focusing part with an IC positive refractive power, a part of a variator with a negative refractive power, and a part of a compensator with a positive refractive power. The present invention relates to a telephoto zoom lens consisting of a relay lens system and a relay lens system.

General ((Although telephoto zoom lenses are highly praised for their maneuverability, the sharpness of the focal point must be quite large.)
4: There is a problem of lack of portability, and there is a demand for something small and lightweight. Although efforts were made to shorten the overall length of the lens and to reduce the number of lenses as much as possible in the design of this lens, there were various difficulties.

In order to shorten the total length of the lens, it is first essential to make the variable power system small, but it takes a lot of time to make the variable power system small by Although it is effective, if you try to make the variable power system smaller by increasing the refractive power sound of the FL variator, you will end up giving each nonce that makes up the variator a strong curvature. The amount of aberration increases. Under such conditions, it is extremely difficult to properly correct spherical aberration, coma aberration, and astigmatism over the entire magnification range. Also, with the teletype relay lens system, Although the overall length can be shortened, the astigmatism caused by making the variable power system smaller can be canceled out, and residual spherical aberration and comatic aberration can be reduced to a satisfactory state (C corrected, and the negative increased by the variable power system) In order to sufficiently correct the Petzval sum, it is necessary to increase the total number of elements in the relay lens system itself, resulting in a complicated and heavy lens.

The purpose of the present invention is to provide a compact and lightweight system consisting of a variable power system including three groups having positive, negative, and positive powers and a relay lens system, and to sufficiently correct various aberrations over the entire variable power range due to zooming. The aim is to provide a telephoto zoom lens with a unique design.

The telephoto zoom lens 1 according to the present invention includes, in order from the object side:
One of the two positive lens components is a composite component,
a first group as a focusing section that has a positive power when combined; a second group that is a part of a variator that includes two negative lens components, one of which is a bonded component and has a negative power when combined; A variable magnification system is constructed with a third group as part of a compensator having positive power, including all positive lens components, and a front group including a positive lens component and a negative lens component, and a negative meniscus lens convex toward the image side. A no-lens system is constructed by the rear group including the component and the biconvex l-nons component, and the composite focal length of the relay lens system is rb, the focal length of the first group is k f +, and the composite focal length of the relay lens system is The radius of curvature of the object-side and image-side surfaces of the convex negative meniscus 1-nons component is ra I '711, respectively, and the focal length of the first group is f1 + the second group. The total focal length of f2. When the radii of curvature of the object-side and image-side surfaces of the object-side negative lens component of the second group are respectively ro and r6, the following conditional expressions are fully satisfied.

Each condition will be explained below.

Condition (1) shows the basic relationship between the variable power system and the relay lens system; if the focal length of the first group is made smaller beyond the lower limit, the variable power system becomes too small, resulting in higher-order spherical aberrations, Comatic aberrations and higher-order chromatic aberrations increase, making it extremely difficult to compensate for various aberrations satisfactorily over the entire zoom range4.

On the other hand, if the upper limit is exceeded, aberrations can be easily corrected, but the overall shape becomes large, which defeats the purpose of making the lens compact and lightweight.

Condition (2) This fully defines the shape of the negative meniscus lens component convex to the image side of the rear group of the fd relay lens system, and the astigmatism that occurs in the variable magnification system is completely eliminated over the entire variable magnification range. It is intended to supplement. If the lower limit of this condition is exceeded, the field curvature will be excessive in the negative direction, and if the upper limit is exceeded, the field curvature will be excessive in the positive direction.

Condition (3) stipulates the correlation of movements for zooming between the second group of a part of the variator and the third group of a part of the compensator, while keeping the variable magnification system entirely afocal. It is.

If the lower limit of the conditions is exceeded, the amount of shift I in a part of the compensator increases, making it difficult to make the variable power system smaller. If the upper limit is exceeded, the form of the curved movement of a part of the compensator will include a sharp U-turn on the long focal length side, which is undesirable because the structure of the lens mirror will inevitably become complicated.

In terms of aberrations, if the lower limit is exceeded, the result will be worse than the Petzval sum C, making it difficult to correct astigmatism in a well-balanced manner with other aberrations, and further improving spherical aberrations including chromatic aberration and coma aberration over the entire magnification range. There is also a tendency for it to become difficult to correct. If the upper limit is exceeded, each aberration can be easily corrected, but the mechanical drawbacks described above will occur.

Condition (4) is effective for preventing distortion from becoming excessively negative on the short focal length side, and at the same time for maintaining better balance of the image plane at both ends of the variable power range. If the lower limit is exceeded, negative distortion will occur significantly on the short focal length side and cannot be corrected by other components, and the variation between the long focal length side will be excessive, and if the upper limit is exceeded, the short focal length Even if negative distortion can be suppressed on the distance side, it becomes difficult to maintain perfect image plane balance over the entire zoom range.

In the telephoto zoom lens of the present invention as described above, the relay lens system has a simple structure as described above (2 components in the front group and 2 components in the rear group, a total of 4 components), but this is due to the miniaturization of the variable power system. The increase in various aberrations can be sufficiently corrected,
This telephoto zoom lens is compact, lightweight, and has high performance.

Examples of the present invention will be described below. The first embodiment shown in FIG. 1 has the Lehrens system configuration as described above, and for each group of the variable power system, the first group is the positive lens component L.
1 and the laminated positive lens component L2, the second group metal lens component L2, the laminated negative 1 nons component L4, and the third group laminated positive lens component, respectively. . The first example is a telephoto zoom for 35iIII11 still cameras! As nons, focal length 80-200 rnm
It has an F number of 4.5. In this example, the telephoto ratio (
The ratio of the distance from the frontmost nonce surface force to the longest focal length to the focal plane) is about 10, and this type of telephoto zoom 1 nonce has a /T type (lζ configuration).

In FIG. 4, 1 shows aberration diagrams in each focal length state of the first embodiment, and it can be seen that a good aberration state is maintained in any state.

The specifications of the first embodiment are described below. However, r.

γ2. r3... is the radius of curvature of the refractive surface of each lens sequentially from the object side, d,, d2... d3 ・-・・
... is the center thickness and air spacing of each lens, 1L, tL
2...'' and ν1, ν2...- represent the refractive index and Atsube number of each lens for the d-line, respectively, f is the composite focal length of the entire system, and B and f are Huck's It represents the focus. (The same applies to the embodiment of Iya) 1st embodiment 7' = 80.0 to 127.98 to 19 B, f, = 45.952 to 45.95 Telephoto ratio: 1. 0
13≦6.785 F number 4.5 2-4 5. 9 5 2 rL, = 1.51680 1', = 64.21L2
= 1.75570 2 = 27.2, = 1.613
75 shi3=56.31313~43.313 rL4= 1.72000 1/, =50.2ru, =
1.60000 shi5=64.27L6=1.761
82 Shiro=26.5!3.197~1.532 t'L? = 1.62041 Schiff = 60.3rL8
= 1.62004 178=35.3! , 177-9
．． 870 Focal length of each group 1st group: fl = 120.192 2nd group: f2 = 40.158 3rd group' f3
"" 110.664 rele lens system front group: f4
= 109.576 rear group: f5 ”” 3313.
715 synthesis: JR = 117.244 n, = 1.56384 ν = 60.8 l, 2 = 1.
51823, 2== 59.0 In the first embodiment described above, the image-side lens component in the first group and the object-side lens component in the second group were laminated lenses. In the second embodiment of the present invention shown, all the lens components on the object side of the first group are bonded together. This embodiment also has a focal length of 80 to 200 mm and an F number of 45, and even if the configuration of each group of the variable power system changes, the relay lens system has a simple configuration similar to that of the first embodiment and is sufficiently effective. It shows that there is. In addition, in the third embodiment of the present invention, as shown in FIG. 3, in the structure of the first and second groups similar to those of the second embodiment, the power of the third group is relatively strengthened to increase the imaging magnification. 〃
This makes it possible to take extremely close-range shots of up to 300 degrees, and for this purpose, the entire power of the third group is divided into two components, , L, and all aberrations are well corrected. This example also has a focal length of 80~200u+3 and an F number of 45, but for extremely close-up photography, the third group k is 20.0 in the shortest focal length state.
This is done by moving the image side by mm.

The specifications of the second and third embodiments are listed below, and the aberration diagrams of each embodiment are shown in FIGS. 5 and 6, respectively.

Second example f = 80.0 to 127.98 J3. f, =45.881~4 Telephoto ratio: 1.017~196.785 F number 4.5 5°881~45.881 1'L+=1.75570 C, =27.2rL,,=
1.61375 1/2=56.3n3=1.5168
0 1/3 = 64.230.317 ~ 44.317 TL+ = 1.72000 1/, = 50.2 le, =
1.60000 Si1=64.2t'L6 =1.76
182 Shiro = 26.5 ~ 22.768 ~ 1103 le, -1,62041 Schiff = 60.3 n8 = 1.62004 v8 = β6.3 - 2.304
~9.997 Focal length of each group 1st group: f, = 120.192 2nd group' f2 = 40.158 3rd group: f3: 110.664 Front group of Lillet lens system: f4 = 109.576 Rear Group: f
! , =-2984,698 synthesis: f, = 117
．． 244 n, = 1.56384 ν 2608 le. =1.74950 ν =35.0η, =1.7
1300 ν 2539 TL+2-1.51823 ν 259.0 3rd example f = 80.0 ~ 126.50 ~ B, f, = 54.181 ~ 54 Telephoto ratio: 0.996 200, OF number 45 181 ~54.181 le -1.80518 shi, = 25.5 le 2 = 1.52
ν Near 0,1 rL3=1,51118 1'a ”'50.9~44
．． 989 rL4 = 1.713 C - 53,9 L, = 1.58913 C, = 61 -, 2 m. =1.8
0518 Shi,,=25.54~1,492'rL7=1.50137 Schiff=56.5L,=1.
52 ν8=70. ] Focal length of each group 1st group: fl=116.052 2nd group:
, /'2" 35.371 3rd group: +3=90
．． 899 Relevance system Front group: f, = 107.088 Rear group: f, = -673,394 Synthesis: fR, = 128.793 rLg = 1.75692 v, = 31.7846~2.
758 rL102 1.6583 shi, o=57.3 3. =1
．． 74077 ν, 277”+2= 1.76684
shi, 2=46.6TL+a=1.54072 shi, 3
=47.2

[Brief explanation of the drawing]

Figures 1 to 3 (show the first to third embodiments of the lens type of the present invention), and Figures 4 to 6 are aberration diagrams at each focal length state of the first to third embodiments. Yes. Applicant: Nippon Kogaku Kogyo Co., Ltd. Yuki Yasui - 1st

Claims (1)

[Claims] In order from the object side, there is a first group as a focusing unit having a positive refractive power, a first group having a negative refractive power, and mainly converting the focal length by moving the optical axis -A. a variable magnification system consisting of a second group as a part of a variator that performs refracting, and a third group as a part of a compensator that has positive refractive power and keeps an image plane that fluctuates in a predetermined position as the part of the variator moves; A telephoto zoom consisting of the variable magnification system and a relay lens system following it! The relay lens system includes a front group including a positive lens component and a negative lens component, and a rear group including a negative meniscus 1-nons component convex to the image side and a biconvex positive lens component, The first group includes two positive lens components, one of which is a diatonic component, and one of which is a bonded component, the second group includes two negative one-tone components, one of which is a bonded component, and the third group includes at least one positive lens component, one of which is a bonded component. Let the composite focal length of the relay lens system be fR1 and the radius of curvature of the object-side and image-side surfaces of the negative meniscus lens component convex to the image side in the rear group of the no-lens system as ra and rb, respectively. , the focal length of the first group 'f: f+, the focal length of the second group e, /'2. A telephoto zoom lens, wherein the following conditional expressions are fully satisfied, where the curvature radii of the object-side and image-side surfaces of the object-side negative lens component of the second group are ro and rd, respectively.