Imaging apparatus

An apparatus, comprising:

• an imaging device including a plurality of first count units and a plurality of second count units arranged in a matrix direction, the first count units each counting a number of first pulses generated by an avalanche effect based on a light beam entering from an exit pupil of an imaging optical system, and the second count units each counting a number of second voltage pulses generated by the avalanche effect based on a light beam entering from a part of the exit pupil of the imaging optical system;
• and
• a controller having a processor which executes instructions stored in a memory or having circuitry, the controller being configured to function as
• a generation unit configured to generate image data based on count values of the respective first count units;
• a detection unit configured to detect a focus state of the imaging optical system based on count values of the respective second count units;
• and
• a control unit configured to control a count period of the first count units and a count period of the second count units,
• wherein the control unit includes a histogram generation unit and a determination unit, the histogram generation unit generating a histogram of the count values of the plurality of second count units, and the determination unit determining an exposure state of a plurality of light receiving units corresponding to the plurality of second count units based on the generated histogram, and
• wherein the control unit controls the count period of the second count units based on a result of the determination by the determination unit.