| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize an entire imaging optical system while suppressing an incident angle on an image surface. SOLUTION: The imaging optical system includes a first lens group G1 including an aperture stop and a second lens group G2 in order from an object side. By moving the second lens group G2 in an optical axis direction, focusing is performed. The first lens group G1 includes a front group G1a on a subject side of the aperture stop, and a rear group G1b on an image surface side of the aperture stop. The front group G1a includes at least two negative lenses and at least one positive lens and has positive refractive power as a whole. By suppressing entire length of the front group, the optical system is miniaturized. COPYRIGHT: (C)2010,JPO&INPIT
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