| 摘要 |
PROBLEM TO BE SOLVED: To provide a miniaturized and image shiftable variable power optical system constituting of shifting images by moving at least one lens component in a direction almost vertical to an optical axis as a shift lens group and by satisfying specified conditions. SOLUTION: A first lens group G1 and a fifth lens group G5 are moved to an object side, one lens component among the lens components for constituting a forth lens group G4 is moved in the direction almost vertical to the optical axis as the shift lens group and thus, the image is shifted. Then, when a using magnification at the telescopic end of the shift lens group is defined asβat , the using magnification at the telescopic end of a lens group arranged more on an image side than the shift lens group is defined asβbt , the focal distance of the entire lens system at the telescopic end is defined as ft and a synthetic focus distance at the telescopic end of the lens group arranged more on the object side than the shift lens group is defined as fct, the conditions of 2.5<(1-βat ).βbt <5 and -0.1<ft/fct<-0.005 are satisfied.
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