There is a Lumedyne head wedged between brickss behind the wall on the right of the frame and it is et to 1/4 power (50 joules) with the protective diffuser cap over the reflector both for safety and diffusion. It is pointed at the wall behind our man and there is a small piece of wood placed so that none of the flash strays onto him while he works.
My guess at the exposure was that it would be about f11 and so I shot a test frame at 1/250th at f11.
There was definitely no detail in the student but the background was still a little dark. I opened up to f8 and also pointed the flash head down a bit and shot a dozen different pictures on a 70-200 f2.8 L lens. The distance between me and the student seemed to relax him and he really got into being a silhouette working away in his hole in the wall.
After a while he relented and we shot some pictures which did identify him, but by then I had this and I was pretty sure that the image would not only run that week but also be a keeper for the archive appropriately keyworded.