发明名称 Zoom lens system
摘要 A compact zoom lens system allowing excellent image quality regardless of an object distance, is disclosed. The disclosed zoom lens system comprises, in order from an object side to an image side, a first, a second, and a third lens units having a positive, a positive, and a negative optical powers, respectively. The spacings between the first and second lens units and between the second and third lens units are changed during zooming. The second lens unit is constituted by, in order from the object to image side, a first lens subunit having a positive or negative optical power and a second lens subunit having a positive optical power. At least the second lens subunit is moved toward the object side to change the spacing between the first and second lens subunits during focusing on an object at a short distance from an object at infinity at least one zoom position.
申请公布号 US6940663(B2) 申请公布日期 2005.09.06
申请号 US20040823019 申请日期 2004.04.12
申请人 CANON KABUSHIKI KAISHA 发明人 NISHIO AKIHIRO
分类号 G02B15/163;(IPC1-7):G02B9/12;G02B15/14 主分类号 G02B15/163
代理机构 代理人
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