This photo was apparently taken at a sci-fi fan gathering sometime in the 1970s.
Mike Hinge (left) (1931 - 2003) was a New Zealand-born artist who contributed some memorable artwork to Heavy Metal magazine in the 80s.
Lou Stathis (center) (1952 - 1997) wrote the 'rok' (i.e., rock) music column for Heavy Metal during the late 70s and early 80s.
I don't know who John Singer (right) was / is.....?
The photo is credited to Steve Stiles, http://fanac.org
The website Onyx Cube, while not maintained after 2017, contains some interesting information about Mike Hinge and his artwork.