Blow-Up is the greatest film about film. It is full of complexity, ambiguities, and ideas about the nature of the medium. It is also among the most influential of movies, spawning everything from direct descendants (Blow-Out by Brian DePalma and The Conversation by Francis Ford Coppola) to a host of movies which show its influence. The photographer photographs something at a distance in the park. But what has he photographed? The difficulty of interpreting that which is filmed is central to the paradoxes of Antonioni's great work.