| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a compact zoom lens providing a bright image with high variable power while maintaining high optical performance at all times without degrading optical performance even if a temperature change occurs. Ž<P>SOLUTION: The zoom lens is formed by arranging, in order from the object side, a first lens group G<SB>1</SB>comprising two lenses which are a first lens L<SB>11</SB>and second lens L<SB>12</SB>and having negative refractive power as a whole, a second lens group G<SB>2</SB>comprising two lenses which are a first lens L<SB>21</SB>and a second lens L<SB>22</SB>and having positive refractive power as a whole, and a third lens group G<SB>3</SB>comprising a lens L<SB>31</SB>having positive refractive power. The second lens group G<SB>2</SB>comprises an optical diaphragm STP specifying a predetermined aperture on the first lens group G<SB>1</SB>side. The zoom lens is compact and provides a bright image with high variable power while maintaining high optical performance at all times without degrading the optical performance even if the temperature change occurs by fulfilling predetermined conditions. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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