| 摘要 |
PURPOSE:To detect the aperture value of a photographing lens with a simple mechanism in which the luminous flux transmitted through a photgraphing lens is bisected and is supplied to photoelectric transducers respectively different in size of photodetecting surfaces. CONSTITUTION:The luminous flux transmitted through a photographing lens 2 is bisected by a semitransparent mirror 11. One of the luminous fluxes if supplied to a photoelectric transducer 12. The other luminous flux is applied through a small lens 4 disposed in the position optically equivalent to the transducer 12 to a photoelectric transducer 16 having the photodetecting surface smaller than the projected image of the exit pupil of the min. aperture diameter of the lens 2. The outputs from both transducers are then subjected to prescribed arithmetic processing, by which the signal relating to the aperture value of the lens 2 is obtd. The aperture value of the photographing lens is thus detected with the simple mechanism. |
