| 摘要 |
A zoom lens system includes a negative first lens group and a positive second lens group. The negative first lens group includes a negative lens element and a positive lens element. The positive second lens group includes a positive lens element, a negative lens element, and a positive lens element. At least the object-side positive lens element and the negative lens element are cemented together. The zoom lens system of the present invention satisfies the following conditions: <?in-line-formulae description="In-line Formulae" end="lead"?>1.5<F<SUB>2G</SUB>/(f<SUB>T</SUB>/f<SUB>W</SUB>)<3.0 (1)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>1<f<SUB>2G</SUB>(m<SUB>W</SUB>-m<SUB>T</SUB>)/(f<SUB>T</SUB>/f<SUB>W</SUB>)<3 (2)<?in-line-formulae description="In-line Formulae" end="tail"?> wherein f<SUB>2G</SUB>: the focal length of the positive second lens group; m<SUB>W</SUB>: the lateral magnification of the positive second lens group at the short focal length extremity; and m<SUB>T</SUB>: the lateral magnification of the positive second lens group at the long focal length extremity; f<SUB>T</SUB>: the focal length of the entire zoom lens system at the long focal length extremity; and f<SUB>W</SUB>: the focal length of the entire zoom lens system at the short focal length extremity.
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