| 摘要 |
PROBLEM TO BE SOLVED: To achieve miniaturization or the like of a zoom lens while securing a zoom ratio not exceeding 3-4 times. SOLUTION: The zoom lens comprises a first negative lens group, a second lens group having an aperture diaphragm, and a third positive lens group. In variable magnification from a wide angle end to a looking far end, the first lens group is moved to an image face side moved to an object side from a middle, the second lens group is moved to the object side, and the third lens group is moved to the image face side. The first lens group includes a double concave lens 2, and the second lens group includes a negative connection lens connecting a positive double convex lens 5 and a negative double concave lens 6. A focal distance of the first lens group fG1, a focal distance of the second lens group fG2, a focal distance of a lens system at the wide angle end fw, and Abbe's numbers of the double convex lens 5 and the double concave lens 6ν5 andν6 satisfy the following expression: 1.3≤¾fG1¾/fG2≤1.5, 2.0≤¾fG1¾/fw≤2.8 and ¾ν5-ν6¾≥20. Consequently, the miniaturized zoom lens can be obtained while securing the zoom ratio not exceeding 3-4 times. COPYRIGHT: (C)2006,JPO&NCIPI
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