Patent ID: 7173776

Claim:
A fisheye lens system comprises a negative front lens group, a diaphragm, and a positive rear lens group, in this order from an object; and said fisheye lens system has a half angle-of-view of 90Â°, wherein said negative front lens group comprises at least three negative meniscus lens elements each of which has the convex surface facing toward the object; and wherein said three negative meniscus lens elements satisfy the following conditions: 0.2<SF (i=1) <0.6 0.8 <SF (i=2) /SF (i=1) <1.5 0.8 <SF (i=3) /SF (i=1) <2.0 wherein SFi designates the shaping factor of the i th (1â‰¦iâ‰¦3) negative meniscus lens element (SFi=(R 1 i âˆ’R 2 i )/(R 1 i +R 2 i )); R 1 i designates the radius of curvature of the object-side surface of the i th (1â‰¦iâ‰¦3) negative meniscus lens element; and R 2 i designates the radius of curvature of the image-side surface of the i th (1â‰¦iâ‰¦3) negative meniscus lens element.