Optical: systems and elements – Lens – Reverse telephoto
Patent
1998-03-06
1999-09-07
Epps, Georgia
Optical: systems and elements
Lens
Reverse telephoto
359651, 359663, 359682, 359784, G02B 1304, G02B 300, G02B 1322, G02B 912
Patent
active
059495898
ABSTRACT:
Negative, positive, and positive lens groups are disposed successively from the larger conjugate length side, and focal length adjustment is effected by the convex lens disposed on the smallest conjugate length side of the first lens group, thereby yielding a long back focus and a telecentric characteristic, decreasing distortion and chromatic aberration, and simplifying the focusing structure. Successively from the larger conjugate length side, a first lens group G.sub.1 having a negative refracting power and including a convex lens L.sub.5 disposed on the smallest conjugate length side, a second lens group G.sub.2 having a positive refracting power and causing a luminous flux diverged by the first lens group G.sub.1 to become substantially afocal, and a third lens group G.sub.3 having a positive refracting power are disposed, and the convex lens L.sub.5 disposed on the smallest conjugate length side of the first lens group G.sub.1 is moved on an optical axis so as to effect focus adjustment.
REFERENCES:
patent: 3856386 (1974-12-01), Fujioka
patent: 3874770 (1975-04-01), Shimizu
patent: 3923369 (1975-12-01), Nakamura
patent: 3958865 (1976-05-01), Sakai
patent: 3981563 (1976-09-01), Nakamura
patent: 4025170 (1977-05-01), Kawamura
patent: 4046459 (1977-09-01), Kawamura
patent: 4061421 (1977-12-01), Nakagawa
patent: 4437735 (1984-03-01), Momiyama
patent: 5331462 (1994-07-01), Yano
patent: 5812326 (1998-09-01), Yamada
Epps Georgia
Fuji Photo Optical Co., Ltd.
Lester Evelyn A.
Snider Ronald R.
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