PURPOSE: To simplify the constitution of a circuit by controlling an output provided toward an object to be photographed, and reducing a dynamic range of a means for detecting a reflected output and a dynamic range of a means for processing an output of the detecting means.

CONSTITUTION: A photographic lens 17 is interlocked with a projecting lens 1 and a projecting element 2 so that an object to be photographed being at a short distance is focused when the projecting lens 1 and the projecting element 2 are projected to a short distance, and an object to be photographed being at a long distance is focused when they are projected to a long distance. A resistance value of a variable resistance 6 is set to control an output of the projecting element 2 so that a current generated in a photodetector 8 becomes the same level even if an object to be photographed having the same reflection factor is at a long distance or a short distance. The photographic lens 17 and the variable resistance 6 are interlocked, the moving extent of the photographic lens is large, a variable range of the variable resistance becomes wide, and an output of the projecting element is controlled more exactly.