| 摘要 |
A positive-negative-positive-positive-positive zoom lens changes magnification by moving each of a first group to a fourth group so as to alter the interval between each group. The third group comprises first and second lens components, at least one of which has an aspheric surface, and the first lens component is a positive-negative-positive cemented lens in sequence from the object side. The zoom lens satisfies the conditional expressions, 7<beta2t/beta2w<10, 5<beta3t/beta3w<12, 0.7<(beta2t/beta2w)/(beta3t/beta3w)<1.65) (where: beta2t is the lateral magnification of the second group at the telephoto end; beta2w is the lateral magnification of the second group at the wide end; beta3t is the lateral magnification of the third group at the telephoto end; and beta3w is the lateral magnification of the third group at the wide end).
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