A diaphragm apparatus for the collimation of an X-ray bundle of an X-ray device is provided for scanning an examination object. An X-ray device including the diaphragm apparatus is also provided. In an embodiment, the diaphragm apparatus includes two diaphragms in the form of slotted diaphragms arranged in series in the direction of the X-rays and mounted to be positionable with respect to one another. Each of the diaphragms includes a fixed diaphragm aperture corresponding to maximum collimation of the X-ray bundle and a region that is impermeable to X-rays, which in each case includes an extension corresponding to the diaphragm aperture corresponding to the maximum collimation.
