| 摘要 |
PROBLEM TO BE SOLVED: To provide a high variable-power reflecting imaging optical system made compact and having a wide angle of view. SOLUTION: The imaging optical system has a first lens group including a catoptric element which reflects luminous flux nearly at a right angle, and a succeeding lens group in order from an imaging object side, and performs variable power from a wide angle end to a telephoto end by making an axial space between the first lens group and an image surface large, and also satisfies relation; 4<(TLw/dr)×(y/fw)<6 when the length of the entire system at the wide angle end is defined as TLw, the axial space of the catoptric element is defined as dr, the maximum image height of the image surface is defined as y, and the focal distance of the entire system at the wide angle end is defined as fw. COPYRIGHT: (C)2007,JPO&INPIT
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