Film blackening area measuring equipment

摘要

An amplification-factor of the amplifier is controlled so as the output from a film-detecting-mechanism to be supplied as the input into a subtractor is adjusted fitting to a reference signal-prior to the film-insertion into the detecting mechanism. The output-signal from a comparator is supplied into the amplification-factor-variable-amplifier, in which the amplification-factor is controlled depending on the magnitude of the input-signal, and it is kept at the controlled value. Or an intensity of a light source is controlled so as the output from the film detecting mechanism to be supplied as the input into the subtractor is adjusted fitting to the reference-signal prior to the film-insertion into the detecting mechanism.