Abstract

There is provided an exposure control circuit apparatus of a structure such that a momentary change of luminance level can be equivalently disregarded, and a response of an iris can be closer to that of the eye of a human being. This exposure control circuit apparatus comprises: a light quantity detecting circuit for detecting a divisional region to which signal level V of average luminance signal belongs of a large number of divisional regions obtained by dividing the range between the maximum level and the minimum level of the signal level V; a response speed setting circuit adapted for setting the degree of change of response speed in dependency upon an output of the light quantity detecting circuit and such that when at least the signal level V of average luminance signal belongs to the region including the maximum level or the region including the minimum level and that signal level is continuously inputted for a predetermined time, the response speed setting circuit sets the degree of change of the response speed to a larger value; and an exposure time control circuit for varying exposure time on the basis of the response speed set at the response speed setting circuit.