| 摘要 |
A wide-angle lens system includes a negative front lens group and a positive rear lens group, in this order from the object. The negative front lens group includes a negative first sub-lens group and a positive second sub-lens group, in this order from the object. The positive rear lens group includes cemented lens elements having a positive R 1 lens element and a negative R 2 lens element, a positive R 3 lens element having a convex surface facing toward the image, and a positive R 4 lens element, in this order from the object. The wide-angle lens system satisfies the following conditions: <?in-line-formulae description="In-line Formulae" end="lead"?>-0.8<f 1 a/f 1 b<-0.1 (1)<?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?> 0.6<f/fR< 1.1 (2)<?in-line-formulae description="In-line Formulae" end="tail"?> wherein f1a designates the focal length of the negative first sub-lens group; f1b designates the focal length of the positive second sub-lens group; f designates the focal length of the entire wide-angle lens system; and fR designates the focal length of the positive rear lens group.
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