发明名称 Zoom lens
摘要 A zoom lens comprises a front lens group having a positive focal length and a rear lens group having a negative focal length, with the distance between the front and rear lens groups being variable for varying the magnification of the zoom lens. The front lens group comprises a first front lens group having a negative focal length and a second front lens group having a positive focal length, the first and second front lens groups being successively arranged in the order specified from an object side. The first front lens group comprises, in the order named from the object side, at least a positive lens and a negative lens. The second front lens group comprises at least one negative lens and at least two positive lenses. The rear lens group comprises, in the order specified from the object side, a positive lens, a negative lens, a negative lens, and a positive lens. The distance between the first and second front lens groups varies during zooming movement of the zoom lens.
申请公布号 US4909613(A) 申请公布日期 1990.03.20
申请号 US19890347221 申请日期 1989.05.02
申请人 RICOH COMPANY, LTD. 发明人 KIKUCHI, SHUICHI
分类号 G02B13/18;G02B15/16 主分类号 G02B13/18
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