A group of quite old pictures of Instrument Six in stereo. THere is quite a lot going on so the 3D view clarifies them. The top view is of the instrument in photographic mode with a single bulb as a light source while the lower two are of the instrument in real-time mode where you can see the floating shadow directly. For those new to the blog, Instrument Six is able to separate an objects shadow from the surface on which it should land and get the shadow to float in mid air. It is explained in earlier posts, for instance here and here.
Use the normal process for resolving the stereo images.