An apparatus for exposing photosensitive media is disclosed in which the light reaching or passing through photosensitive media is monitored, with the exposure being terminated after the desired amount of light has been received. Slope control circuitry is provided to selectively and non-linearly vary the exposure with variations in the density of originals which are being copied simultaneously. In a wide variety of applications the apparatus produces high quality prints, by automatically compensating for variations in exposure due to, for example, variations in the number of originals being copied.