For stereographic roentogenograph, two photographs are taken from two optically determined positions and viewed with a stereoscope. A film changer for exposures and a prism type stereoscope have been devised to be attached to an ordinary X-ray apparatus for medical examination. A factor T0 is conceived with which the stereoscopic perception can be controlled. Manipulation is made easy by an adjusting device to suit different individuals. An attachment for measuring the exact position of any particular object in the visual field is provided.