| 摘要 |
A photographic objective of the modified double gauss type is presented. The object has a forward group that includes three lens elements (L 1 , L 2 , L 3 ) and has the refractive power sequence ++-. The objective also includes an aperture and a rear group including lens elements (L 4 , L 5 , L 6 ) of refractive power sequence -++. The lens element of negative refractive power (L 4 ) is designed as a meniscus with an aspheric surface concave relative to the aperture, and a lens 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 ).
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