| 摘要 |
PROBLEM TO BE SOLVED: To obtain a wide-angle zoom lens system which comprises a first lens group having negative refractive power, a second lens group having positive refractive power, a third lens group having negative refractive power and a fourth lens group having positive refractive power in order from an object side, where spacing between the first lens group and the second lens group is decreased, space between the second lens group and the third lens group is increased and spacing between the third lens group and the fourth lens group is decreased when varying power from a short focal distance end to a long focal distance end, whose viewing angle is wide such as about 100°and whose variable power ratio (zoom ratio) is about 2.5 to 3 and which is suitable for a camera using a small imaging element. SOLUTION: The wide-angle zoom lens system satisfies following conditional expressions (1) and (2). (1) 0.9<f2/ft<1.2 and (2) 2.9<f4/fw<3.4, provided that fi; the focal distance of the i-th lens group (i=1 to 4), ft; the focal distance of an entire system at the long focal distance end and fw; the focal distance of the entire system at the short focal distance end. COPYRIGHT: (C)2007,JPO&INPIT
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