Four-group zoom lens

Details Four-group zoom lens Four-group zoom lens

1991-06-18

1992-09-08

Henry, Jon W.

Optical: systems and elements

Lens

With variable magnification

359688, G02B 1516

Patent

active

051463660

ABSTRACT:
A zoom lens comprising a first lens group having a positive refractive power; a second lens group having a negative refractive power that moves for zooming; a third lens group movable to correct image surface movement; and a fourth lens group stationary during zooming. The fourth lens group consists of six lenses. The first lens reduces divergence of a light beam. Further, if the overall focal length of the system at the wideangle end is F.sub.W ; the focal length of the second lens group is F.sub.2 ; the focal length of the combination of the second to sixth lenses is F.sub.42 ; and the focal length of the combination of the second to fourth lenses is F.sub.A, then the conditions: ##EQU1## are satisfied.

REFERENCES:
patent: 4720181 (1988-01-01), Hata
patent: 4770510 (1988-09-01), Mukaiya
patent: 4812024 (1989-03-01), Mukaiya
patent: 4824226 (1989-04-01), Tanaka
patent: 4846563 (1989-07-01), Mukaiya
patent: 4934796 (1990-06-01), Sugiura et al.
patent: 5050972 (1991-09-01), Mukaiya et al.
patent: 5056900 (1991-10-01), Mukaiya et al.

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