Wide angle lens system for reflex camera, has first lens groups with positive lens element and negative lens element

摘要

Wide angle lens system with a negative first lens group and positive second lens group arranged in this sequence away from the object. The first lens group comprising at least one positive lens element and at least one negative lens element, as viewed away from the object in this sequence, and the lens system satisfies a predetermined relationship. The wide angle lens system has parameters according to equitation (I) and (II). 0 (pi1-2 + pi2-1)/pi 0.3 (I) 0.5 HF/HL 0.9 (II) pi1-2 = 1-n1/r1-2 (a) pi2-1 = (n201)/r2-1 (b) pi = 1/F (n1) = Refractive index of positive lens element of first lens group(n2) = Refractive index of negative lens element of first lens group(r1-2) = Radius of curvatures of image-side face of positive lens element of first lens group(r2-1) = Radius of curvature of object side face of negative lens element of first lens group(F) = Focal length of total lens system(HF) Radius of one axial light bundle relative to first lens group(HL) Radium of an axial light beam bundle relative to second lens group