This is a clever little horror flick and clearly underrated. It demonstrates the idea of split personality when the photographer Roger (Joseph Farrell) meets his 'alter ego' Rossiter (Kevin Shinnick). Whereas the photographer only arranges scenes with the girls that scare them, but don't actually hurt them, the devil in him breaks out and then takes the job to the extreme. Transformed into Rossiter, Roger may at last torture and kill.
Some reviews below give me the impression most people take movies much too literally, so I elaborate a bit of the transformation idea. Check out 1:00:47 when Roger discovers Rossiters machine. Fascinated, he pulls the lever and says "this is ingenious"! We shall see Rossiter stand at the machine later just like that. Check out 1:10:41 when a hand seems to reach out of Rogers brain (or rather: mind) and smashes him against the door so that he 'dissolves' into an unrecognizable pulp. But when in 1:16:00 Sam Rogan enters the room, there is no body on the floor. Roger has disappeared - he was replaced by Rossiter.
Roger was still full of excuses (his artistic purposes), fear and restrictions. His released inner demon knows nothing of this and just does what Roger may only have had (wishful or terrifying) fantasies about. The actually scary idea behind the movie is therefore that once you lose control, you'll never be the same again. If that involves covering Misty Mundae in red paint, it may however seem negotiable ;-)