Patent ID: 8818183

Claim:
A focus detection apparatus comprising: a control unit configured to cause a photoelectric conversion element in a sensor to accumulate an electric charge; a timer unit configured to measure a time elapsed from when accumulation of the electric charges is started; a measurement unit configured to measure a signal level indicating an amount of the electric charges accumulated in the photoelectric conversion element; a determination unit configured to perform a first determination for determining whether the signal level has reached a first threshold, and to perform a second determination for determining whether the signal level has reached a second threshold that is greater than the first threshold; and a detection unit configured to perform focus detection using a signal obtained from the photoelectric conversion element in the sensor, wherein during a time period from when it is determined that the signal level has reached the first threshold to when it is determined that the signal level has reached the second threshold, the determination unit performs the second determination at a first time interval if an elapsed time from when the accumulation of the electric charges is started to when it is determined that the signal level has reached the first threshold is shorter than a reference time, and performs the second determination at a second time interval that is longer than the first time interval if the elapsed time is longer than the reference time, in a case where it is determined that the signal level has reached the second threshold, the control unit ends the accumulation of the electric charges, and the detection unit performs focus detection using a signal obtained from the sensor after the accumulation of the electric charges has ended.