| 摘要 |
PURPOSE: To miniaturize a whole lens system and to provide high optical performance over all variable power ranges by setting the refractive powers of respective lens groups and the moving conditions of the respective lens groups accompanied by varying the power, etc., within a specified range. CONSTITUTION: At the time of varying the power from a wide-angle end to a telescopic end, the fluctuation of an image plane accompanied by the power variation is compensated by monotonously moving a first group L1 to the side of the image plane and moving a second group L2 to the side of the image plane so as to have a projected locus. Power variation is also performed by monotonously moving a third group L3 and a fifth group L5 to the object side independently or integrally. A fourth group L4 is fixed or monotonously moved to the object side and, by representing the moving amount of the i-th group by power variation from the wide-angle end to the telescopic end by Xi, the conditions: 0<|X1/X3|<1.2, 0<=X4/X3<0.5, 0.5<X5/X3<2 are satisfied.
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