PURPOSE: To obtain natural bright picture planes for outdoor and indoor photography by compressing the level of a light quantity detection signal detected by a level detecting circuit within the dynamic range corresponding to the quantity of indoor light by a nonlinear circuit.

CONSTITUTION: The nonlinear circuit 9 is provided which compresses the level of the light quantity detection signal detected by the level detecting means 5 into the dynamic range corresponding to the quantity of indoor light, and the level is inputted to an error detecting means 6 through this nonlinear circuit 9. Therefore, the high level of the light quantity detection signal detected at the time of outdoor photography is compressed to a level lower than the level corresponding to a track line, so an error value is set small through the error detector 6. Consequently, even if the quantity of reflected light 2 which is limited increases, the picture plane never becomes dark and a natural bright picture plane is obtained.