Patent ID: 8164642

Claim:
An image-capturing device, comprising: a destructive read-type image sensor that executes photoelectric conversion of a light flux from an optical system at a plurality of pixels, stores electrical charges resulting from the photoelectric conversion respectively at the plurality of pixels, outputs a signal corresponding to each of the stored electrical charges at the plurality of pixels to be read out, and destroys the signal therein when the signal has been read out through a destructive read; a read unit that reads out the signal from the image sensor over a specific cycle through the destructive read; a display unit at which display is brought up based upon the signal read out through the destructive read by the read unit each time the read unit reads out the signal through the destructive read; a storage unit that is located outside the destructive read-type image sensor and individually stores signals read out from a specific pixel of the plurality of pixels of the image sensor through the destructive read over plural read operations by the read unit, each signal in correspondence to a read operation; an adding unit that is located outside the destructive read-type image sensor and adds up a plurality of signals obtained sequentially over time among the signals already read out from the specific pixel through the destructive read over the previous plural read operations and stored in the storage unit; and a focus detection unit that detects a focus adjustment state of the optical system based upon adding results provided by the adding unit.