| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens comprising a number of lenses of≤10, having a variable power magnification ratio exceeding 20 tlmes, and having excellent optical performance. SOLUTION: The zoom lens comprising≤10 lenses and having the variable magnification ratio exceeding 20 times is arranged, successively from an object side to an image plane side, with a first lens group GR1 which has positive refracting power and of which the position is fixed during the variable magnification, a second lens group GR2 which has negative refracting power and of which the position is moved during the variable magnification, a third lens group GR3 which has positive refracting power and includes at least one aspherical face, and of which the position is fixed during the variable magnification, and a fourth lens group GR4 which has positive refracting power and includes at least one aspherical face, and of which the position is fixed during the variable magnification, corrects the fluctuation in the image plane position during the variable magnification, and performs focusing. The zoom lens satisfies the following conditional expressions (1): (1) 7.8<dz/fw<8.8, where dz: the movable distance of the second lens group for variable magnification, fw: the focal length at the wide angle end of the entire system of the lens. COPYRIGHT: (C)2007,JPO&INPIT
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