| 摘要 |
A zoom lens system includes, in order from an object side to an image side, first, second, third, and fourth lens units having positive, negative, positive, and positive optical powers, respectively. The first lens unit includes one negative lens element and two positive lens elements, and moves during zooming. The zoom lens system satisfies the following condition: <?in-line-formulae description="In-line Formulae" end="lead"?>0.05<f1/(st1xft/fw)<0.2<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>1.5<beta3T/beta3W<3.6<?in-line-formulae description="In-line Formulae" end="tail"?> where f1 denotes a focal length of the first lens unit, st1 denotes a distance between positions of the first lens unit at a wide-angle end and at a telephoto end, fw and ft denote focal lengths of the entire system at the wide-angle end and at the telephoto end, respectively, and beta3W and beta3T denote lateral magnifications of the third lens unit at the wide-angle end and at the telephoto end, respectively.
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