I believe Jerry Ulesmann created his images in the darkroom using as many as five enlargers, each with a negative. I have seen some of the actual prints and they are flawless. A few years back I had the experience of French photographer Lucien Clergue photographing a model in my backyard at the time of his exhibition in Coral Gables. He actually made double exposures in camera (a simple Minolta 35mm - maybe a 370). He would go to a museum and photograph paintings or parts of paintings and then re-expose the same roll of film with another subject or model. How he kept track of everything and was able to register the frames was beyond me. The photographs he took of the model in our yard were double exposed with exposures of angels at the Getty museum in L.A. That was in 1995-1996. I did photograph him photographing the model with my wife in the foreground. He handheld the camera and didn't bring a tripod. During a later trip to France we had the pleasure of visiting him at his home in Arles.