With the luminous flux from the subject which passes the automatic focusing

摘要

PURPOSE: To shorten the focus detecting arithmetic time during scanning drive, eliminate the missing of a subject even at a high-speed scanning drive, and surely detect the subject when the subject is out of the frame. ;CONSTITUTION: A pair of subject images formed by the luminous flux passed through a photographing optical system 3 is received and converted into a pair of subject image data according to the light intensity distribution, and the correlation degree is arithmetically operated while relatively shifting the subject image data to detect the focusing state of the photographing optical system 3. When the reliability of the detection result of the focusing state is high, the photographing optical system 3 is driven on the basis of the detected focusing state, and when the focusing state can not be detected, or the reliability of the detection result is low, the photographing optical system 3 is scanning- driven, and the quantity of the subject image data is more limited than during non-scanning drive to arithmetically operate the Correlation degree on the basis of the less subject image data, and the focusing of the photographing optical system 3 is detected.;COPYRIGHT: (C)1995,JPO