Long before I knew anything about using Photoshop, I had taken a portrait of a family in their house. It was a fairly close-up, closely posed family of four.
I wanted to use this new stretch of velvet cloth as a black background, for the first time. I didn't really have a way to use it properly, so I had my helper stand behind the background and hold up the bar I had it clamped to, while I photographed the family.
When I got the photographs up, I had this really eerie, ghostly image of my helper in his white shirt, holding his arms outstretched, in crucifixian style, bleeding through the black background.
I asked a friend for help to salvage the images, so he put a halo on the Christ Ghost hovering above the family.