| 摘要 |
953,879. Photographic objectives. VOIGTLANDER A. G. June 15, 1960 [Jan. 11, 1960], No. 21053/60. Heading G2J. A three lens photographic objective, consisting of a simple dispersing lens between two simple collecting lenses is so designed that the length of the objective is between 0.3F and 0.45 F, therefractive indices of the lenses increase from front to rear and in each case the index is between 1.65 and 1. 75, the refractive index of the rear lens is greater than 1.67 and this lens, which is of lanthanum crown glass, has an Abbe number greater than 45, the ratio of the radius of the rear surface of the dispersing lens to the radius of the front surface of the front collecting lens lies between 0.9 and 1.05, the ratio of the front air space to the rear air space lies between 0.85 and 1.1 and the dispersive lens is so bent that the numerical value of the ratio of the radius of its rear surface to the radius of its front surface is between 0.63 and 0. 7. Preferably the ratio of the radius of the front surface of the front lens to the radius of its rear surface is between -.05 and + .05, the ratio of the radio of the surfaces of the rear lens is between 0.20 and 0.30 and the ratio of the thickness of the front lens to that of the rear lens is between 1.15 and 0.9 while at the same time the ratio of the sum of the axial thicknesses of all the lenses to the overall lengths of the objective is less than 0. 5. Optical data are given for one example of the objective shown. |
