Diaphragm control apparatus for camera

Claim 1

In a diaphragm control apparatus for camera including a metering circuit for producing a photometric output corresponding to the light passed through a diaphragm being gradually stopped down in the direction of from its maximum aperture to its minimum aperture prior to start of an exposure; a setting circuit for producing an output corresponding to a preset shutter speed or a preset diaphragm value; a comparing circuit for comparing said photometric output with said preset output and producing a signal when said two outputs get in a certain determined relation; and a diaphragm blocking device for blocking the stopping-down motion of said diaphragm in accordance with the signal from said comparing circuit, the improvement comprising a correcting circuit for detecting that the aperture value has reached a determined value relying upon said photometric output and, when it is detected, applying a correction output to at least one input of said comparing circuit, said correction output being so predetermined as to correspond to the error of stop-down caused by the time delay of from the time point at which said signal is issued from said comparing circuit to the time point at which said stopping-down motion is stopped by said diaphragm blocking device, wherein said correcting circuit comprises a detecting circuit for producing a signal when said photometric output has reached a set output corresponding to an aperture value set by voltage dividing the photometric output obtained when said diaphragm is in the maximum aperture, and a correction output applying circuit for applying said correction output to said comparing circuit according to the signal from said detecting circuit.