发明名称 Zoom lens system for use in a microfilm projection apparatus
摘要 A zoom lens system comprising, in order from an enlargement side, a first lens unit of a negative power, a second lens unit of a positive power and a third lens unit of a negative power. The first lens unit is fixed during a zooming operation from a longest focal length condition to a shortest focal length condition. The second and third lens units are movable from the enlargement side to a reduction side during the zooming operation, with a distance therebetween changing from a decrease to an increase.
申请公布号 US5062695(A) 申请公布日期 1991.11.05
申请号 US19900486060 申请日期 1990.02.27
申请人 MINOLTA CAMERA KABUSHIKI KAISHA 发明人 IWASAKI, SATOSHI
分类号 G02B15/16;G02B15/177 主分类号 G02B15/16
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