| 摘要 |
PURPOSE:To correct easily an angle of equivalent light curtain brightness by fetching only parallel light components from a specified photodetecting window, making then incident on a photodetector through a condenser lens and a mask, and obtaining equivalent light curtain brightness information. CONSTITUTION:An image from a visual object 23 is made incident on photodetectors 27, 31 and a finder 35 through a perforated mirror 25, and a visual object luminance L0, center cavity adaptation brightness Lf and a finder image are derived, respectively. Also, only parallel light components are fetched from the object 23 by a photodetecting window 37 for equivalent light curtain brightness and light shielding plates 37, 38 which have been formed so that the diffusion transmissivity is lowered from the center part of the optical axis to the peripheral part. Subsequently, its parallel light is condensed by a condenser lens 40, its parallel light components are passed through from a mask 41, the luminous flux is diffused by a diffusion plate 42, and the equivalent light curtain brightness Lev is photodetected by a photodetector 43. In this way, angle characteristics of the brightness Lev can be made to conform easily with a theoretical value. |
