Patent ID: 8441570

Claim:
An image pickup apparatus on which a lens apparatus can be detachably mounted, wherein the lens apparatus is provided with an aperture unit including a mechanical shutter mechanism that controls the intensity of light that passes through the lens apparatus, said image pickup apparatus comprising: an image pickup element which converts an optical image of an object incident thereon via the lens apparatus into electrical signals, synchronized with one of vertical synchronizing signals; a brightness information output unit which supplies the lens apparatus with brightness information on the basis of the electrical signals obtained by said image pickup element, synchronized with one of the vertical synchronizing signals; an aperture value obtaining unit which obtains an aperture value provided by the aperture unit, synchronized with one of the vertical synchronizing signals; and a control unit that generates, after an instruction to photograph a still image has been entered and before said image pickup element outputs the electrical signals, aperture control data that varies according to the aperture value obtained by said aperture value obtaining unit to control the aperture unit and transmits the aperture control data to the lens apparatus, synchronized with one of the vertical synchronizing signals, wherein the aperture unit (1) receives the aperture control data transmitted by said control unit synchronized with a first signal of the vertical synchronizing signals, (2) awaits entering of a second signal of the vertical synchronization signals, (3) awaits elapse of a time corresponding to the aperture control data from the entering of the second signal of the vertical synchronizing signals, and (4) in response to the elapse of time, controls the mechanical shutter mechanism to start intercepting the light incident on a lens to photograph the still image, and wherein the second signal is output from the image pickup apparatus to the lens apparatus after receiving the first signal.