Patent US 4,952,963

A focus detection apparatus including an image signal storage type sensor having a plurality of pixels and a storage time control circuit for controlling an intensity level of the sensor, wherein the storage time of an image signal in the sensor is controlled such that the image signal has an optimal level, and focus detection is performed on the basis of the image signal whose storage time is controlled. A pixel output range used for focus detection and a sensor area used for storage time control are changed on the basis of the focus detection result.