| 摘要 |
PROBLEM TO BE SOLVED: To provide a small zoom lens, capable of providing high optical performance over the total zoom range. SOLUTION: The zoom lens has a first lens group with positive refractive power, a second lens group with negative refractive power, an aperture stop, a third lens group with positive refractive power, and a fourth lens group with positive refractive power, in the order from the object side to the image side. When zooming from the wide angle end to the telephoto end, the first lens group moves to draw a protruding trajectory toward the image side, while the aperture stop moves independently from each lens group, and the conditions of -0.6<f2/f3<-0.4 and -0.5<MS/M3<0.9 are satisfied, wherein MS and M3 represent respectively the movement quantities of the aperture stop and the third lens group in the optical axial direction (the movement quantity directed toward the image side is considered positive and that toward the object side negative), and f2 and f3 represent respectively the focal distances of the second lens group and the third lens group. COPYRIGHT: (C)2009,JPO&INPIT
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