| 摘要 |
A wide-angle lens system includes a negative first lens group, a negative second lens group, and a positive third lens group. The negative first lens group includes at least two negative meniscus lens elements each having the convex surface facing toward the object, and a positive lens element provided on the image-side of the two negative meniscus lens elements. The negative second lens group includes cemented lens elements and a negative meniscus lens element having the convex surface facing toward the object. The wide-angle lens system satisfies the following conditions: <?in-line-formulae description="In-line Formulae" end="lead"?>f<SUB>2-3</SUB>/f>1.6 (1) <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>f<SUB>3</SUB>/f>1.5 (2) <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>(f<SUB>2-3</SUB>/f)/(f<SUB>3</SUB>/f)>1.0 (3) <?in-line-formulae description="In-line Formulae" end="tail"?> wherein f<SUB>2-3 </SUB>designates the combined focal length of the negative second lens group and the positive third lens group; f designates the focal length of the entire wide-angle lens system; and f<SUB>3 </SUB>designates the focal length of the positive third lens group.
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