Patent ID: 7936989

Claim:
An image capturing apparatus comprising; an image pickup device to convert an image of a subject into an electrical signal; a photographing optical system to image the subject image on the image pickup device; a diaphragm unit configured to adjust an amount of light passing therethrough by changing a dimension of an aperture stop diameter at plural stages; a filter unit configured to change a transmittance of the passing light amount by advancing the filter unit in a direction perpendicular to an optical axis of the photographing optical system and positioning the filter unit at a position on the optical axis or retracting the filter unit from the optical axis position in a direction reverse to the perpendicular direction, and to thereby adjust the passing light amount; a shutter unit configured to adjust an amount of exposure of the image pickup device by changing an exposure time thereof; and a controller to control operations of the diaphragm unit, the filter unit, and the shutter unit according to a brightness of the subject; wherein the controller controls the amount of exposure of the image pickup device by controlling the diaphragm unit and the shutter unit without advancing the filter unit at the position on the optical axis, between a stage in which the aperture stop diameter of the diaphragm unit is in a released state and a first stage in which the released aperture stop diameter is throttled from the released state to a level of one aperture value, wherein, in a case that the aperture stop diameter of the diaphragm unit is throttled into a the first stage other than the released stage and the filter unit is not advanced onto the optical axis position, according to a change of the subject brightness, the controller advances the filter unit onto the optical axis position and at the same time throttles the dimension of the aperture stop diameter of the diaphragm unit into the first stage and a second stage departed from the first stage by the one aperture value, wherein, in a case that the aperture stop diameter of the diaphragm unit is throttled into the second stage and the filter unit is advanced onto the optical axis position, the controller changes the exposure time of the shutter unit while maintaining the dimension of the aperture stop diameter of the diaphragm unit at the second stage, according to the change of the subject brightness.