FOCUSING CONTROL DEVICE

PURPOSE:To simplify remarkably the whole device by which an automatic controlling circuit for coping with a focusing shift amount, a distance to an object to be photographed and a difference of its reflection factor, etc. becomes unnecessary, or the like, by constituting so that an integral value of a difference, namely, a detecting period of the focusing shift amount is determined by an integral value of the sum of outputs of the first and the second photodetectors. CONSTITUTION:When a light emitting element 11 is made to emit a light by a controlling circuit 38, a reflected light from an object to be photographed 12 is made incident to the first and the second photodetectors 14, 15 of a photodetecting part 13, converted photoelectrically in said elements, and thereafter, it is applied to integrators 23, 27 through each buffer circuit 17, 18 and each amplifier 21, 25. In this state, in case when a photographic lens is front focusing, an output relation of each photodetector 14, 15 is (A>B), therefore, an integral value (A-B) of a difference is positive, and the second comparator 32 generates an output of an H level in the initial state. Also, when an integral value of the sum reaches a fixed threshold level, the first comparator 31 detects it, and generates a detecting signal. This detecting signal is applied to the controlling circuit 38, stops the first and the second integral operations, and also generates a focusing shift detection start signal to an AND gate 35.