Zoom lens

Details Zoom lens Zoom lens

1990-06-04

1991-03-19

Sugarman, Scott J.

350432, G02B 1514, G02B 1318

Patent

active

050005510

ABSTRACT:
A zoom lens comprises, in succession from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power, and is designed such that during the magnification change from the wide angle end to the telephoto end, the air space between the first lens group and the second lens group is enlarged, the air space between the second lens group and the third lens group is reduced and further, the air space between the third lens group and the fourth lens group is varied. The second lens group comprises, in succession from the object side, a negative meniscus lens having its convex surface facing the object side, a biconcave negative lens, and a cemented positive lens consisting of a biconvex positive lens and a biconcave negative lens cemented together, and is designed to satify the following conditions: ##EQU1##

REFERENCES:
patent: 4523814 (1985-06-01), Okudaira
patent: 4629294 (1986-12-01), Tanaka et al.
patent: 4789226 (1988-12-01), Ogata
patent: 4789229 (1988-12-01), Yamanashi
patent: 4871239 (1989-10-01), Masumoto et al.

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