Rear attachment lens

Details Rear attachment lens Rear attachment lens

1980-01-02

1982-07-20

Corbin, John K.

350465, G02B 960, G02B 1502

Patent

active

043402798

ABSTRACT:
In order to increase the focal length of a master lens, a lens of negative power is attached at the rear end of the master lens. This rear attachment lens comprises three lens groups of which the first, counting from the front, is of positive power and consists of a negative meniscus lens of forward convexity and a biconvex lens with the confronting surfaces of these lenses forming a divergent air lens. The second lens group is of negative power, and has at least two pairs of divergent cemented surfaces of opposite curvature particularly for the purpose of achieving improvement of the Petzval sum and good correction of astigmatism simultaneously. The third lens group is of positive power and consists of a positive lens and a negative lens.

REFERENCES:
patent: 3516734 (1970-06-01), Schmidt
patent: 4129359 (1978-12-01), Momiyama
patent: 4154508 (1979-05-01), Nakamura

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