发明名称 Small-size zoom lens system
摘要 A small-size zoom lens system includes a first lens group, a second lens group, and a third lens group which are successively arranged from an object side to an image side. The first, second, and third lens groups have negative, positive, and negative focal lengths, respectively. The first, second, and third lens groups are movable toward the object side for zooming movement from a wide angle end toward a telephoto end, while varying the distances between the first, second, and third lens groups. The focal length of the ith lens group (i=1, 2, 3), and the focal length fw of the entire zoom lens system at the wide angle end of zooming movement satisfy the following conditions: 0.3<¦f3¦/¦f1¦<1 1.2<¦f1¦/fw<2.3 0.9<¦f3¦/fw<1.
申请公布号 US4955700(A) 申请公布日期 1990.09.11
申请号 US19890398915 申请日期 1989.08.28
申请人 RICOH COMPANY, LTD. 发明人 YAMAGUCHI, TAKAO
分类号 G02B13/18;G02B15/177;G02B15/20 主分类号 G02B13/18
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