| 摘要 |
PURPOSE:To reduce negative Petzval sum and prevent the mechanical interference with a master lens by specifying the entire and partial synthetic powers of a lens system, radii of curvature, and respective positive and negative average refractive indices. CONSTITUTION:The lens system is constituted, successively from object side, of the 1st negative lens L1 directing its strong concave face to the image side, the 2nd biconvex positive lens L2, the 3rd negative lens L3, the 4th negative lens L4 directing its strong concave fact to the object side, and the 5th positive lens L5. This lens system is mounted to the image side of a photographic lens system, whereby the focal length of the lens is magnified to about 1.4 times. The synthetic power phi0 of the entire part of the system, the partial synthetic powers phi1,2,3 of the 1st-3rd lenses, the phi4,5 of the 4th-5th lenses, the radius of curvature on the object side of the lenses and the radius of curvature on the image side, Ri, Ri', the average refractive index value Np of positive lenses, the average refractive index value Nn of negative lenses, and Abbe number nui are specified to the relations of the equations (1)-(5). |
