Rear focus type zoom lens

Details Rear focus type zoom lens Rear focus type zoom lens

1990-06-07

1992-07-28

Arnold, Bruce Y.

Optical: systems and elements

Lens

With variable magnification

359683, G02B 1500

Patent

active

051345242

ABSTRACT:
A zoom lens of the rear focus type is disclosed, comprising, from front to rear, a first lens group of positive power, a second lens group of negative power, a third lens group of positive power and a fourth lens group of positive power, wherein zooming from the wideangle end to the telephoto end is performed by axially moving the first, second and fourth lens groups in differential relation to one another, and focusing is performed by axially moving the fourth lens group alone.

REFERENCES:
patent: 3501224 (1970-03-01), Takahashi
patent: 4256381 (1981-03-01), Kreitzer
patent: 4634236 (1987-01-01), Masumoto
patent: 4695133 (1987-09-01), Kitagishi et al.
patent: 4720180 (1988-01-01), Asano et al.
patent: 4802747 (1989-02-01), Horiuchi
patent: 4818083 (1989-04-01), Mihara
patent: 4832471 (1989-05-01), Hasmano
patent: 4859042 (1989-08-01), Tanaka
patent: 4865434 (1989-09-01), Matsushita et al.
patent: 4909615 (1990-03-01), Ueda
patent: 4917482 (1990-04-01), Ito
patent: 4934796 (1990-06-01), Sugiura
Patent Abstracts of Japan, vol. 12, No. 313, with Respect to Japanese Patent Document No. 63-81313 (Apr. 12, 1988) Aug. 25, 1988.

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