| 摘要 |
PROBLEM TO BE SOLVED: To secure sufficient peripheral light quantity without enlarging the diameter of a lens and to provide high optical performance all over the area of zooming by specifying the ratio of the focal distance of a 1st group to that of an entire system at a telephoto end, the ratio of the moving amount of the 1st group to that of a 4th group and the ratio of the moving amount of a 5th group to that of a 4th group in a telephoto zoom lens consisting of seven groups. SOLUTION: This lens is provided with 1st, 2nd, 3rd and 4th groups L1, L2, L3 and L4 having positive, negative, negative and positive refractive power, respectively, a 5th group L5 constituted of a diaphragm and 6th and 7th groups L6 and L7 having positive and negative refractive power, respectively, in order from an object side. The 1st to the 6th groups are moved to the object side so as to perform variable power from a wide-angle end to the telephoto end, and the 7th group is moved to perform image surface moving associated with the variable power. Assuming that the focal distance of the 1st group is f1 and that of the entire system at the telephoto end is fT, 0.4<f1/fT<0.6 holds, assuming that the moving amount of the 1st group is m1 and that of the 4th group is m4, 0.4<m4/m1<0.7 holds, and assuming that the moving amount of the 5th group is m5, 0.5<m5/m4<1.0 holds.
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