Patent ID: 6853495

Claim:
A wide-angle lens system comprising: a first lens group that is located on the object side and has an overall negative refractive power; and a second lens group that is located on the image side of the first lens group and has an overall positive refractive power, wherein said first lens group comprises first and second lenses formed as meniscus lenses that are disposed next to each other in that order from the object side and are convex on the object side, the image side concave surface of said second lens is aspherical and the variation in the thickness (d) of said second lens within its effective radius is set to fall within a first prescribed range, the divergence between the radius of curvature R 12 on the image side of said first lens and the radius of curvature R 21 on the object side of said second lens is set to fall within a second prescribed range, and the deviation between the difference d 2 between the radii of curvature of said first and second lenses along the optical axis and the focal length (f) of the lens system comprising said first lens group and said second lens group is set so as not to exceed a prescribed value, and wherein, where the thickness of said second lens along the optical axis is deemed d 0 and the thickness along the normal line at a given distance from the optical axis within the effective radius is deemed (d), the variation in the thickness of said second lens is defined as d/d 0 , for which said first prescribed range is 0.8 to 1.2 (0.8<d/d 0 <1.2) the divergence between the radii of curvature of said first and second lenses is defined as R 21 /R 12 , for which said second prescribed range is 0.9 to 1.1 (0.9<R 21 /R 12 <1.1), and the deviation between the difference d 2 between the radii of curvature of said first and second lenses along the optical axis and said focal length (f) is defined as d 2 /f, for which said prescribed value is 0.2 (d 2 /f<0.2).