This is an original photo that the reshoot unit camera crew used as reference to do a pick up, or repeat the shot of Luke/darth vader´s head decapitated, months after main photography ended.
This photo shows the prop head filmed in the main filming, that had to be reshoot as the prop head didnt look convincing. Then they buried Mark Hamill in a box from below, and shot his real face, using this photo as reference to check the camera angle, light, smoke, .. etc.
More from Star Wars: Episode V - The Empire Strikes Back (1980)
