PURPOSE: To execute the exact photometry caused by an auxiliary light emission by a suitable light quantity irrespective of a reflection factor and a distance of an object by repeating the auxiliary light emission until all of the reflected light quantities measured by plural photometric means exceed a prescribed value.

CONSTITUTION: By setting a terminal PR to 'L', an auxiliary light emission is commanded to an electronic flash device. As a result, when the stroboscopic device executes the auxiliary light emission, the terminal PR is reset to 'H', and integral voltages of integral capacitors C1, C10 - C14 are read through analog-to-digital converters A/D0 - A/D5. In the case all outputs of the converters A/D0 - A/D5 are a small value, the terminal PR is set to 'L' →'H' again and the stroboscopic device is subjected to auxiliary light emission, and it is repeated until all outputs exceed such a large value (k) as an error can be disregarded. In such a way, an exact photometry can be executed irre spective of a reflection factor and a distance of an object.