| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens for compact camera high in variable power, small is size and reduced in the number of component lenses. SOLUTION: In the zoom lens composed of a 1st lens group I with a positive power and a 2nd lens group II with a negative power in order from an object side, the 1st lens group I is constituted of a 1st negative lens group I-1 and a 1st positive lens group I-2, and the negative lens group I-1 is composed of a 1st lens L1 with a negative power and a 2nd lens L2 provided with an aspherical surface whose curvature radius is made gentle as it comes closer to off-axis with reference to the paraxial spherical surface in order from the object side, and the 1st positive lens group I-2 is composed of a positive single lens L3, and also, the zoom lens system satisfies the following conditional inequalities 1 and 2; (1) 4<fT/f1 G<6, (2) 75<νd , wherein, fT denotes the focal distance of the whole system at a long focal distance end, f1 G denotes the focal distance of the 1st lens group andνd denotes the Abbe number of the 1st positive lens group I-2(positive single lens).
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