The classic instance of this projector-related incomprehension among academics came for me during a 1982 Rosalind Krauss lecture at the Society for Photographic Education National Conference in Colorado Springs. Krauss put one of Cindy Sherman’s “Untitled Film Stills” images on the screen and left it there for a good twenty minutes. Inevitably, the bulb generated heat in the small space between itself and the slide, warming the celluloid substrate that carries the image. The substrate swelled and buckled slightly, which popped the image out of focus. “Focus that,” Krauss would order. Finally, clearly frustrated, and evidently ignorant of basic thermodynamics, Krauss snapped, “This is a roomful of photographers! Doesn’t anyone know how to focus?” At which point the emulsion on the Sherman on the screen started to melt. […]