| 摘要 |
PROBLEM TO BE SOLVED: To provide a zoom lens which has a wide viewing angle of the wide angle end, is small-sized and bright, moreover, requires only a small number of lenses and is low-cost by using a composition of at least four groups of positive-negative-positive-positive. SOLUTION: The zoom lens is constituted by arranging a first group optical system G1 having a positive focal distance, a second group optical system G2 having a negative focal distance, a third group optical system G3 having a positive focal distance, and a fourth group optical system G4 having a positive focal distance in order from the object side. The first group optical system G1 is composed of a positive lens L1. Upon the zooming, the first group optical system G1, the third group optical system G3 and the fourth group optical system G4 are moved on the optical axis in accordance with variable power from the short focus wide-angle end to the long focus telephoto end, however the second group optical system G2 is fixedly arranged for the image surface and is not moved. COPYRIGHT: (C)2006,JPO&NCIPI
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