An apparatus for transilluminating a film includes a light source emitting a light beam for transilluminating the film, a film guide for guiding the film such that the light beam can transilluminate a section of the film, a film feed for feeding the film to the film guide, and a film removal for removing the film from the film guide. The film guide has a support designed for rotation about a rotation axis running through the center of the support and a rotationally symmetric circumferential surface. The film can be supported on the circumferential surface at least with part of the width thereof over a section of the circumferential surface. The light beam generated by the light source passes through the film when the film is supported on the circumferential surface at least with part of the width thereof over a section of the circumferential surface.