Reflective photometric device for focal plane shutter

Abstract

Abstract PURPOSE: To make the exposure time proper, by correcting the integral value, which is obtained by measuring the reflection light from the black leading screen face and the film face by a photoelectric conversion element, by an adding circuit and a sample hold circuit. CONSTITUTION: The reflection light from shutter leading screen face B and film face E different is reflection factor is measured to generate an integral voltage. This integral voltage is supplied to the sample hole circuit consisting of hold capacitor C 2 and operational amplifier OP 3 to be able to hold it, and the output voltage of this circuit is corrected by the reflection correction coefficient. This corrected output voltage and the integral voltage are added by the summing amplifying circuit consisting of resistances R 0 , R 0 /n, and operational amplifier OP 2 , thus obtaining output voltage V 3 corrected properly. Here, (n) indicates the coefficient based on the difference between reflection factors of the standard film face and the black leading screen face. Thus, even if the leading screen face and the film face are different in reflection factor, an accurate exposure time can be determined. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Kazunori Mizogami

Bibliographic Details