| 摘要 |
PROBLEM TO BE SOLVED: To obtain a four-group zoom lens achieving miniaturization in the entire length of the lens, and having excellent optical performance all over the variable power range from a wide angle end to a telephoto end. SOLUTION: In the zoom lens having four lens groups in order from an object side to an image side, a distance dm from a surface top on the object side of the lens arranged nearest to the object side in a first lens group to the surface top on the object side of the lens arranged nearest to the object side in a third lens group at a zoom position Za where the first lens group is positioned nearest to the image side; the focal distance fm of the lens entire system at the zoom position Za; moving amount X1 on an optical axis in zooming of the first lens group from the wide angle end to the telephoto end; the focal distances of the lens entire system at the wide angle end and the telephoto end, which are defined as fw and ft respectively; and the ratioβ3z of the image forming magnification at the telephoto end to that at the wide angle end of the third lens group are appropriately set. COPYRIGHT: (C)2007,JPO&INPIT
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