Patent ID: 7102834
Filing Date: 2006-09-05
Classification: G02B

Abstract:
1. A photographic objective of the modified double gauss type having a front group, comprising three lens elements L 1 , L 2 , L 3 and having the refractive power sequence positive, positive, negative, an aperture and a rear group including lens elements L 4 , L 5 , L 6 of refractive power sequence negative, positive, positive, wherein in the rear group the lens element of negative refractive power L 4 is designed as a meniscus with an aspheric surface concave element of negative refractive power L 7 with surfaces concave on both sides is arranged downstream of the last lens element of positive refractive power L 6 ; wherein the two lens elements of the rear group of positive refractive L 5 ,L 6 are fabricated from a high-index glass, and the downstream lens element of negative refractive power L 7 comprises glass with a low Abbe number.