RANGE FINDER

PURPOSE:To prevent the generation of out-of-focus at a central part by measuring the distance of an adjacent part corresponding to the range finding result of the central part of a visual field only at a necessary time. CONSTITUTION:At first, when the light emitting element IR2 provided in the center of a range finding zone is allowed to emit light, the emitted light is projected on an objected on an object 2 through a projection lens 11 and the reflected light is incident on a unidimensional semiconductor position detection element 14 through a light detection lens 12. The distance up to the object 2 is cleared from the incident position. If this distance is infinite, the adjacent light emitting element IR1 is allowed to emit light and the range finding of the adjacent zone is performed. If this measured distance is not infinite, said distance is set as a measured value and, when the measured distance is infinite, the range finding of the adjacent zone is further performed. This operation is repeated and, when the measured distance is infinite until the last, infinity is set to a measured value.