| 摘要 |
PROBLEM TO BE SOLVED: To obtain a lens having decreased aberration fluctuations by production errors by limiting the power and moving quantity of a 4-group zoom lens group having positive, negative, positive and positive refracting power successively from an object side and further, introducing an aspherical surface to the third group. SOLUTION: This zoom lens comprises the 4-group zoom lens group having the positive, negative, positive and positive refracting power successively from the object side and moves the first lens group I, third lens group III and the fourth group IV to the object side while expanding the air spacing between the first lens group I and the second lens group II and reducing the spacing between the second lens group II and the third lens group III when making variable power from a wide angle end to a telephoto end. In such a case, focusing is executed by moving the second lens group II and the condition equations 0.50<|f2|/fw<0.60, 0.25<|f2|/f3<0.35, 0.28<|f2|/f4<0.36 are satisfied. In the equations, fw is the focal length at the wide angle end; f2 is the focal length of the second lens group; f3 is the focal length of the third lens group and f4 is the focal length of the fourth lens group.
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