Abstract: An electronic flash unit is caused to perform a pre-flash immediately before a photographing operation, and the quantity of light reflected by the subject during the pre-flash is measured by a flash metering unit. Based upon the output from the flash metering unit, a decision is made as to whether or not another pre-flash is to be implemented. Based upon the results of the decision-making, another pre-flash is performed if necessary. Thus, if the quantity of light measured by the flash metering unit during the pre-flash is too small or too large and a sufficient degree of accuracy is not achieved in the measurement, another pre-flash is performed to assure a high degree of accuracy in metering.

Abstract: A distance measurement apparatus comprises a light emitting device for emitting light to an object, a light receiving device including a plurality of photocells for receiving light emitted by the light emitting device and reflected by the object, an adding circuit for adding outputs of an arbitrary number of photocells from among the plurality of photocells, and a control circuit for controlling the light emitting device, the light receiving device and the adding circuit. The control circuit comprises a determining circuit for determining a first group of photocells having a maximum addition result based on the addition performed by the adding circuit, and a calculating circuit for setting a second group of photocells comprised of the first group of photocells and a single or a series of photocells contiguous to the first group of photocells, dividing the second group of photocells into element subgroups, and calculating a distance to an object based on outputs of respective divided element groups.