Compact zoom lens

U.S. Patent Number: 5270865

Abstract: A compact zoom lens has first to fourth lens groups sequentially arranged from an object side. The first, second and fourth lens groups respectively have negative, positive and negative focal lengths. When a zooming operation is performed from a wide angle end to a telescopic end, a distance between the first and second lens groups is decreased, a distance between the second and third lens groups is increased, and a distance between the third and fourth lens groups is decreased. Focal lengths f.sub.1 and f.sub.2 of the first and second lens groups, focal lengths f.sub.2,3,4W and f.sub.2,3,4T of a combined lens system of the second, third and fourth lens groups at the wide angle end and the telescopic end, a focal length f.sub.3,4T of a combined lens system of the third and fourth lens groups at the telescopic end, focal lengths f.sub.W and f.sub.T of an entire lens system at the wide angle end and the telescopic end satisfy the following conditions where symbol .sqroot.[ ] means a square root of a value within bracket [ ].

Inventors: Kikuchi; Shuichi (Yokohama, JP), Itoh; Masami (Higashi-Kurume, JP)

Assignee: Ricoh Company, Ltd. (Tokyo, JP)

Application Number: 07/942,273

Issued: 1993-12-14

Expired: 2005-12-14

Classes: 359/686

Field of search: 359/686,685

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