| 摘要 |
A fisheye lens system includes a negative first lens group and a positive second lens group, which are defined with respect to a maximum air-distance between lens elements constituting the fisheye lens system. The negative first lens group includes a first negative meniscus lens element having the convex surface facing toward the object, a second negative meniscus lens element having the convex surface facing toward the object, and a negative third lens element. The fisheye lens system satisfies the following conditions: 0.25<SF 1 <=1.0 . . . (1); 0.1<SF 2 <=1.0 . . . (2); 0.9<SF 3 <2.1 . . . (3); SF 1: the shaping factor of the first negative lens element (SF 1 =(r 1 -r 2 )/(r 1 +r 2 )); r 1 and r 2: the radius of curvature of the object-side surface and the image-side surface of the first negative lens element; SF 2: the shaping factor of the second negative lens element (SF 2 =(r 3 -r 4 )/(r 3 +r 4 )); r 3 and r 4: the radius of curvature of the object-side surface and the image-side surface of the second negative lens element; SF 3: the shaping factor of the negative third lens element (SF 3 =(r 5 -r 6 )/(r 5 +r 6 )); r 5 and r 6: the radius of curvature of the object-side surface and the image-side surface of the negative third lens element.
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