An imaging apparatus for imaging on a recording medium is improved to permit the imaging power to be balanced between various groups of individual radiation sources with a low outlay and high accuracy. Two or more imaging heads that respectively include a multiplicity of individual radiation sources that can be electrically driven individually with light beams directed onto a radiation-sensitive layer of the recording medium. A drive moves the recording medium and the radiation sources relative to one another. A control device controls the power of the light beams of the radiation sources separately for each imaging head. A least one light guide is provided that guides a portion of the light beams emanating from the radiation sources to the receiver surface of a photoelectric sensor, which sensor is connected to the control device.