The disclosure relates to a mobile X-ray device having an equipment cart that is movable on wheels and has a lifting device on which a support assembly is arranged. A C-arm is mounted to the support assembly so as to be displaceable along the circumference of the support assembly, wherein the C-arm has an X-ray source and an X-ray receiver arranged opposite the X-ray source. In order to simplify the handling of a mechanical zoom on mobile X-ray devices, a motion controller is provided by which, in any given pose of the C-arm, a movement of the C-arm is controlled in such a way that the central axis extending between X-ray source and X-ray receiver is fixed in space.