Why did paintings suddenly take on a nearly photographic realism around 1420? In this controversial program, noted artist and art critic David Hockney investigates how, 400 years before the invention of the photograph, painters were using simple cameras—the camera lucida, camera obscura, and convex mirror—to capture realistic images. Hockney visits Florence, Bruges, and Ghent, examining dozens of paintings by such masters as Jan van Eyck, Vermeer, Holbein, Caravaggio, and Velázquez. In a specially designed Hollywood set he demonstrates his findings and replicates the lost techniques of the Old Masters. A BBC Production. (73 minutes)