发明名称 Compact zoom lens system and digital camera using the compact zoom lens system
摘要 A zoom lens apparatus includes a first optical lens group having a negative focal length, a second optical lens group having a positive focal length, and a third optical lens group having a positive focal length, arranged in this order from a subject. The lens groups move such that a distance between the first and second optical lens groups is decreased and a distance between the second and third optical lens groups is increased at a scaling change to a long focal length edge. The second optical lens group includes two positive lenses, a negative meniscus lens, and a positive meniscus lens. The zoom lens system satisfies an inequality condition 0.15<(N<SUB>22</SUB>-N<SUB>23</SUB>)<0.40, in which N22 is a refractive index of the negative meniscus lens and N23 is a refractive index of the positive meniscus lens conjoined with the negative meniscus lens.
申请公布号 US6995921(B2) 申请公布日期 2006.02.07
申请号 US20040935263 申请日期 2004.09.08
申请人 RICOH COMPANY, LTD. 发明人 OHASHI KAZUYASU
分类号 G02B15/14;G02B13/00;G02B15/177 主分类号 G02B15/14
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