Many photographs seem to be images of absences: for instance, a photograph of a shadow seems to be an image of an absence, as shadows are plausibly thought of as being absences of light. Absence photography is puzzling, however, as, first, it is a common idea that photographs can only be images of things that have caused them, and, second, it is unclear whether absences can cause anything. In this paper, I look at various ways to unravel the puzzle. Along (...) the way, I also hope to cast some light on the idea that photography is a causal medium. (shrink)