| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable power optical system that is sufficiently small and excellent in optical performance to be suitably used for a digital camera, a portable terminal, a mobile telephone, etc. SOLUTION: The system is composed of at least a negative first lens group, a positive second lens group, a negative third lens group, and a positive fourth lens group. In this system, in varying power from the wide angle end to the telephoto end, at least the second and the third lens group are moved along the optical axis. The front principal point position of the second lens group is designed to come closer to the object side than the second lens group, thereby reducing the total length of the optical system and also securing enough space for the variable power. COPYRIGHT: (C)2005,JPO&NCIPI
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