Patent ID: 6057971
Filing Date: 2000-05-02
Classification: G02B

Abstract:
A wide-angle lens system, in order from an object side of said wide-angle lens system, comprising:a front lens group; anda rear lens group,wherein an aperture stop is disposed midway between said front and rear lens group,wherein said front lens group consists of, in order from the object side of said wide-angle lens system, a negative meniscus lens having a strong concave surface directed to an image side of said system and a positive lens, two lenses in all, andsaid rear lens group consists of up to three lenses in all, including a double-convex lens component composed of a single lens or a cemented lens and located nearest to the image side of said system, and which satisfies the following conditions:-0.2<f/f.sub.F <0.3 (II-1-6)0.3<D.sub.FS /D.sub.SR <1.6 (II-2-6)1.5<D.sub.SR /f<5 (II-3)-0.5<(r.sub.R1 +r.sub.R2)/(r.sub.R1 -r.sub.R2)<0.5 (II-4)0.1<D.sub.12 /D.sub.FS <0.7 (II-5)where f is a focal length of the overall lens system, f.sub.F is a focal length of said front lens group, D.sub.FS is a distance between a surface vertex of said front lens group located nearest to the object side of said system and said aperture stop, D.sub.SR is a distance between said aperture stop and a surface vertex of said rear lens group located nearest to the image side of said system, r.sub.R1 and r.sub.R2 are paraxial radii of curvature of object- and image-side surfaces of the double-convex lens component of said rear lens group and located nearest to the image side of said system, respectively, and D.sub.12 is an optical axis air separation between the negative meniscus lens of said front lens group that has a strong concave surface directed to the image side of said system and said positive lens.