| 摘要 |
PROBLEM TO BE SOLVED: To obtain a miniaturized and high-performance variable power optical system, in the variable power optical system of negative, positive, and positive lens groups, starting from the side of an object, in this order. SOLUTION: In varying the power from the short-focal length end to the long-focal length end, a third lens group is fixed, a first and a second lens groups are movable, and the variable power optical system satisfies the conditional expressions (1) 3.0<f3/f2<3.5, (2) 1.4<¾f1/fw¾<2.0, and (3) 0.8<f2/fw<1.5, where fi is the focal length of an i-th lens group, fw is the focal length of the total system at the short-focal length end, and ft is the focal length of the total system at the long-focal length end. COPYRIGHT: (C)2005,JPO&NCIPI
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