Standard lens with wide picture angle

Abstract

Abstract PURPOSE:To make back focus to >=0.9 time a focal distance and make the configuration compact to efficiently compensate various aberrations in a lens system having F2 and a 56 deg. picture angle to be used for a 35mm. single-lens reflex camera by composing the lens system of 6 Gaussian lenses and satisfying specific conditions. CONSTITUTION:A lens system is composed of a front group consisting of a positive meniscus lens L1 with a projected surface opposed to the object side, a negative meniscus lens L2 with a projected surface opposed to the object side and a positive meniscus lens L3 with a projected surface opposed to the object side and a back group consisting of a negative meniscus lens L4 with a projected surface opposed to the image side, a positive meniscus lens L5 with a projected surface opposed to the image side and a convex lens L6 with projected surfaces on both the sides and conditions (1)-(8) are satisfied. Where, n1-n6 are the refractive indexes of lenses L1-L6 to a line (d), fF is the composite focal distance of the front group, r5 is the radius of curvature of the lens L3, r9 is the radius of curvature of the lens L5 on the object side, r12 is the radius of curvature of the lens L6 on the image side, and (f) is the composite focal distance of the whole system. Consequently, a lens system having an aperture ratio of F/2 and a about 56 deg. picture angle is obtained.

Inventors

• 👤 Yasushi Ogata
• 👤 康司 小方

Bibliographic Details