| 摘要 |
PURPOSE:To obtain a lens for copying which is bright with a vignetting factor of almost 100% and F number of 4 and, at the same time, well corrected in various aberrations by constituting the optical system of the lens of six lenses of six groups. CONSTITUTION:The optical system of this lens for copying is constituted of six lenses of six groups in such a way that the 1st- and six-group lenses are constituted of convex meniscus lenses 10 and 20 having the same optical property and the 2nd- and 5th-group lenses are constituted of concave meniscus lenses 12 and 18 having the same optical property. The 3rd- and 4th-group lenses are constituted of convex meniscus lenses 14 and 16 having the same optical property and the lenses are perfectly symmetrically arranged about a diaphragm 15 provided at the center. In addition, nonspherical surfaces are adopted to the convex surfaces of the 1st- and 6th-group lenses are concave surfaces of the 2nd- and 5th-group lenses and this lens system is constituted so that the system can satisfy the conditions of Inequalities (I)-(III). The K1, K2, and K3 of the inequalities respectively represent the cone constants of the convex surfaces of the 1st- and 6th-group lenses, concave surfaces of the 2nd- and 5th-group lenses, and concave surfaces of the 3rd- and 4th-group lenses. |
