| 摘要 |
PURPOSE:To prevent a position shift, also to reduces a material cost, the number of parts and a mnufacturing process, and to simplify an assembly work, and to improve an optical function, by molding not only a fitting colloar piece but an optical function part, as one body by synthetic resin, as to a pentagonal Dach- prism for a finder optical system of a single-lens reflex camera. CONSTITUTION:As a material of a prism, synthetic resin is used, and fitting collar pieces 31, 41 to an optical apparatus body, an eyepiece function part 32, a capacitor Fresnel lens function part 42, a focal plate 33, a picture frame display function part, etc. are molded as one body with the prisms concerned 30, 40. Since composition of functions by a single member can be realized, it is possible to reduce material and molding costs, and an assembly adjusting cost, due to reduction of the number of parts, and not only the assembly accuracy is elevated but the eyepiece function surface and the capacitor lens function surface can be formed unspherically, and circumferential image distortion and circumferential illumination shortage can be corrected, therefore, the optical function can be improved. |
