Wide-angle lens system

A method for manufacturing a wide-angle lens system that comprises 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 is composed of a first lens being disposed on the object side and a second lens having an aspherical concave surface and a thickness (d) within the effective radius of the lens that is set to fall within a first prescribed range, both of said lenses being meniscus lenses, the first and second lenses are formed such that the divergence between the radius of curvature R12 on the image side of said first lens and the radius of curvature R21 on the object side of said second lens is set to fall within a second prescribed range, and the deviation between the difference d2 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, said first lens group is formed by arranging said first and second lenses in an adjacent fashion in that order from the object side such that they are convex on the object side, and said second lens group is disposed on the image side of said first lens group while being separated therefrom by a prescribed distance.

An optical device comprising:

• a wide-angle lens system;
• and
• a CCD camera disposed behind said wide-angle lens system,
• wherein said wide-angle lens system comprises 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;
• 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 lens within its effective radius is set to fall within a first prescribed range, the divergence between the radius of curvature R12 on the image side of said first lens and the radius of curvature R21 on the object side of said second lens is set to fall within a second prescribed range, and the deviation between the difference d2 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.