PURPOSE: To control a photographing lens at the correct peak position and also to focus-lock and unlock, by providing a timing circuit, a CPU, a stepping motor, a pulse generating circuit and a display circuit for a range finding result.

CONSTITUTION: The average of output of an A/D comparator 70 separately at the time when a projecting element 2 is turned on and the time when it is turned off is taken by a CPU72 at each step of a timing circuit 50 and the average at the on-time is reduced by the average at the off-time and the step having the largest difference is stored by the CPU72. A display circuit 86 for range finding results displays a distance in accordance with the step stored in the CPU72. A pulse generating circuit 78 generates a pulse in accordance with the step stored in the CPU72 in a stepping motor 76 and automatic focus control is performed by moving a photographing lens 74 to a focusing position. A focus-locking and a focus-unlocking are made easily as a range finding operation is finished by scanning of the element 2 and stored without moving the lens 74.