Zoom lens system

Details Zoom lens system Zoom lens system

Filed on

1991-10-11

Date issued

1993-06-29

Examiner

Arnold, Bruce Y.

Patent Class

Optical: systems and elements

SubClass

Lens

SubSubClass

With variable magnification

Other Related Categories

359686, 359688, G02B 1514

Type

Patent

Status

active

Patent number

052239799

Description

ABSTRACT:
A four-group zoom lens system that achieves satisfactory brightness and zoom ratio for practical applications and yet is compact and can be manufactured at low cost. The lens system includes in order from the object to the image side, a positive first lens group, a negative second lens group, a negative third lens group, and a positive fourth lens group composed of a positive front lens unit (4.sub.f) and a positive rear lens unit (4.sub.r), the first to third lens groups being capable of moving independently of one another along the optical axis. The front lens unit (4.sub.f) includes in order from the object to the image side, a positive first lens element (4.sub.1) having a convex surface on the image side, a positive second lens element (4.sub.2), a positive third lens element (4.sub.1) having a convex surface on the object side and a negative fourth lens element (4.sub.4) having a concave surface on the object side. The rear lens unit (4.sub.r) includes at least two lens elements which are a positive fifth lens element (4.sub.5) having a convex surface on the object side and a negative meniscus sixth lens element (4.sub.6) having a concave surface on the image side and which are arranged in order from the image to the object side.

REFERENCES:
patent: 4113356 (1978-09-01), Matsuhara
patent: 4490017 (1984-12-01), Okudaira et al.
patent: 4572620 (1986-02-01), Kikuchi
patent: 4591244 (1986-05-01), Aono et al.
patent: 4626076 (1986-12-01), Oshima et al.
patent: 4629293 (1986-12-01), Mihara
patent: 4659187 (1987-04-01), Tsuji et al.
patent: 4699474 (1987-10-01), Ozawa
patent: 4701084 (1987-10-01), Mihara
patent: 4765722 (1988-08-01), Aomo

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