A reflecting stereoscope has picture holders and oculars for the observation of pictures held by the picture holders, and an optical train between the picture holders and the oculars. Picture marks and measuring markers carrying adjustable measuring marks are interposed in the optical train and there is a measuring device for measuring the location of the measuring marks. The picture holders are disposed in the focal plane of the oculars and a lens system on the optical axis of the oculars projects the magnified image of the measuring marks onto the focal plane of the oculars. Partially reflecting mirrors in the light path of the optical train observe picture marks and the measuring marks. A special system for moving the measuring markers and measuring their position is provided.