Patent ID: 6707621
Filing Date: 2004-03-16
Classification: G02B

Abstract:
A wide-angle lens comprising, from an object side to an image plane side:a first lens group comprising: a first lens having a negative refractivity, and a second lens having a positive refractivity; and a second lens group comprising: a third lens having a negative refractivity, a fourth lens having a positive refractivity, said fourth lens being bonded to said third lens, and a fifth lens having a positive refractivity, said fifth lens comprising a first convex surface oriented to said object side and a second convex surface oriented to said image plane side, at least one of said convex surfaces being an aspherical surface; wherein:(1) 0.7|R6|(2) &ugr;1>&ugr;2, &ugr;350 (3) |f1|>2 f2 (4) 2.5 f22>f21>f22, where R6 is a curvature radius of an object-side surface of said third lens;R8 is a curvature radius of an image plane-side surface of said fourth lens; &ugr;i is an Abbe number of an i-th lens (i=1-5); f1 is a composite focal length of said first lens group; f2 is a composite focal length of said second lens group; f21 is a composite focal length of said third and said fourth lenses in said second lens group; f22 is a focal length of said fifth lens in said second lens group.