High variable power ratio zoom lens

U.S. Patent Number: 5379154

Abstract: In a zoom lens having, in succession from the object side, a first lens unit having positive refractive power, a second lens unit having positive refractive power, and a third lens unit having negative refractive power, the spacing between the first lens unit and the second lens unit being increased and the spacing between the second lens unit and the third lens unit being decreased during the magnification change from the wide angle end to the telephoto end, the first lens unit has at least one positive lens and at least one negative lens, the second lens unit comprises, in succession from the object side, a front group of weak refractive power and a rear group of positive refractive power, the front group having at least one negative lens and at least one positive lens, the rear group having, in succession from the object side, at least one positive lens, at least one negative lens and at least one positive lens, and the third lens unit has at least one positive lens and at least one negative lens. The zoom lens satisfies predetermined conditions.

Inventors: Shibayama; Atsushi (Kawasaki, JP), Sato; Susumu (Chiba, JP)

Assignee: Nikon Corporation (Tokyo, JP)

Application Number: 08/097,030

Issued: 1995-01-03

Expired: 2007-01-03

Classes: 359/689 ; 359/684; 359/686

Field of search: 359/689,686,687,684

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