High-speed photographic or cinematographic objective with wide image angle

摘要

848,375. Photographic objectives. SCHNEIDER. M. C. Sept. 11, 1958 [Oct. 11, 1957], No. 29113/58. Class 97(1) A photographic objective having an angle of view exceeding 50 degrees and a back focal length between 1.5F and 2.5F (F = equivalent focal length) comprises on the object side a negative part-system I consisting of a positive doublet L1, L2 and a negative doublet L3, L4 and a positive part-system II spaced therefrom by an air gap exceeding 2.5F but less than 3.5F, and consisting of positive doublets L5, L6 and L8, L9 with a single biconvex lens L7 therebetween. Preferably, the contact surfaces in the front doublets are concave towards each other, as also are the contact surfaces in the doublets of the positive part-system. The difference in refractive index at each cemented surface in the front doublets may exceed 0.22, whereas the corresponding difference in the rear doublets is less than 0.22. Optical data are given for the example shown.