Caravaggio experimented with lighting effects in his paintings and used models from the street - two centuries before the great photographic pioneers. Whether it's in Cartier-Bresson's immediacy or Bill Brandt's sepulchral shadows, you catch hints of Caravaggio's intensely lit and passionately sensual world in the work of the most brilliant photographers. Of course this is no coincidence. Caravaggio was rediscovered because of the camera...