Optical: systems and elements – Lens – Reverse telephoto
Patent
1998-08-10
2000-03-14
Epps, Georgia
Optical: systems and elements
Lens
Reverse telephoto
359763, 359770, G02B 1304, G02B 960
Patent
active
060380853
ABSTRACT:
A super wide angle lens, having a viewing angle greater than 120 degrees, and an F-number of about 1.2 is disclosed. The lens is formed of a first lens group G.sub.1 of negative refractive power, a second lens group G.sub.2 of positive refractive power, and a third lens group G.sub.3 of positive refractive power. The lens is designed so that the lens elements used in the lens groups may be easily and economically manufactured. The first lens group has a first lens element L.sub.1 composed of a negative meniscus lens with its convex surface on the object side, and a second lens element L.sub.2 composed of a negative meniscus lens with its convex surface on the object side. The second lens group includes a third lens element L.sub.3, that is biconcave, cemented to a fourth lens element L.sub.4 that is biconvex. The third lens group has four lens elements: a fifth lens element L.sub.5 composed of a negative meniscus lens, with its convex surface on the object side; a sixth lens element L.sub.6 composed of a biconvex lens cemented to the fifth lens element; a seventh lens element L.sub.7 composed of a negative meniscus lens, with its convex surface on the object side; and an eighth lens element L.sub.8 composed of a biconvex lens cemented to the seventh lens element.
REFERENCES:
patent: 3741630 (1973-06-01), Nakagawa
patent: 3856386 (1974-12-01), Fujioka
patent: 4009943 (1977-03-01), Horimoto
patent: 4310222 (1982-01-01), Ikemori
patent: 4634237 (1987-01-01), Aono et al.
patent: 5159493 (1992-10-01), Tsutsumi
Arnold Bruce Y.
Epps Georgia
Fuji Photo Optical Co., Ltd.
Schwartz Jordan M.
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