| 摘要 |
PURPOSE:To obtain the copying lens having good performance in a wide variable power region which can cover even the wide angle of view above a half angle of view by consisting the lens of 4 elements in 4 groups and forming the lens which satisfies specific conditions. CONSTITUTION:The copying lens constituted of the 4 elements in 4 groups consisting, successively from an object side, of a positive meniscus 1st lens, the convex face of which is directed to an object side, a negative meniscus 2nd lens, the convex face of which is directed to the object side, a negative meniscus 3rd lens, the convex face of which is directed to the image side, and a positive meniscus 4th lens, the convex face of which is directed to the image side is so constituted as to satisfy the conditions of equations I to IV where the focal length of the entire system is designated as FM, the focal length of the i-th lens as fi, the radius of curvature of the i-th face at ri, the thickness or spacing of the i-th lens as di, the overall length of the lens as SIGMAd. The copying lens which can include up to the neighborhood of half angle of view omega=25 to 30 deg. is attained by the simple constitution of the 4 elements in 4 groups. |
