| 摘要 |
PROBLEM TO BE SOLVED: To obtain a high-performance compact zoom lens whose zoom ratio is about 3 and which is constituted of a small number of lenses, that is, ten lenses by moving the 1st and the 3rd lens groups in an object direction and satisfying a specified condition. SOLUTION: This lens is such a zoom system that the 1st and the 3rd lens groups I and III are moved in the object direction while extending a distance between the 1st lens group I and a 2nd lens group II and shortening a distance between the 2nd lens group III and the 3rd lens group III in the case of performing variable power from a wide-angle end to a telephoto end. The conditions 0.65<|fII/fw|<0.75, 0.77<|fIII/fw|<0.80, 1.00<|fIII/fII|<1.20 and 2.60<|fI/fIII|<3.20 are given to the power of respective groups provided that (fw) is a focal distance at the wide-angle end, fI is the focal distance of the 1st lens group I, fII is the focal distance of the 2nd lens group II, and fIII is the focal distance of the 3rd lens group III. Thus, the high-performance compact telephotographic zoom lens constituted of four to five lenses, which is smaller than in the conventional zoom lens, is obtained.
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