Imaging system where a quick return mirror is returned to a down state and a stop is returned to a fully open state before the accumulation period ends

摘要

An apparatus has an image sensing device, and a signal processing device for performing a first image sensing operation for making the image sensing device perform an image sensing operation in an exposure state to obtain a sensed image signal, and a second image sensing operation for making the image sensing device perform an image sensing operation in a non-exposure state to obtain a sensed image signal, and processing the sensed image signal obtained by the first image sensing operation by the sensed image signal obtained by the second image sensing operation. The signal processing device determines in accordance with the image sensing time of the first image sensing operation whether or not the second image sensing operation is performed.