Patent ID: 7317581

Claim:
A fisheye lens system comprising a negative first lens group and a positive second lens group, in this order from an object, wherein said negative first lens group and said positive second lens group are defined with respect to a maximum air-distance between lens elements constituting said fisheye lens system; wherein said negative first lens group comprises 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, in this order from the object; and wherein said fisheye lens system satisfies the following conditions: 0.25<SF 1 ≦1.0 0.1<SF 2 ≦1.0 0.9<SF 3 <2.1 wherein SF 1 designates the shaping factor of said first negative meniscus lens element (SF 1 =(r 1 −r 2 )/(r 1 +r 2 )); r 1 designates the radius of curvature of the object-side surface of said first negative meniscus lens element; r 2 designates the radius of curvature of the image-side surface of said first negative meniscus lens element; SF 2 designates the shaping factor of said second negative meniscus lens element (SF 2 =(r 3 −r 4 )/(r 3 +r 4 )); r 3 designates the radius of curvature of the object-side surface of said second negative meniscus lens element; r 4 designates the radius of curvature of the image-side surface of said second negative meniscus lens element; SF 3 designates the shaping factor of said negative third lens element (SF 3 =(r 5 −r 6 )/(r 5 +r 6 )); r 5 designates the radius of curvature of the object-side surface of said negative third lens element; and r 6 designates the radius of curvature of the image-side surface of said negative third lens element.