| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zoom lens that has a small entire optical system, a high-zoom-ratio, and a high optical performance over the entire zoom range. SOLUTION: The zoom lens includes first to fourth lens groups in order from the object side to the image side. The first, third, and fourth lens groups have a positive refractive power. The second lens group has a negative refractive power. During zooming from a wide-angle end to a telephoto end, the first lens group moves along a locus convex toward the image side, the second lens group moves along a locus convex toward the image side from the wide-angle end to an intermediate zoom position and along a locus convex toward the object side from the intermediate zoom position to the telephoto end, and the third lens group moves such that the distance to the second lens group at the telephoto end is smaller than that at the wide-angle end. Focal length f1 of the first lens group and focal length ft of the entire lens system at the telephoto end are adequately set. COPYRIGHT: (C)2010,JPO&INPIT
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