Ever since Kodak modified a Nikon SLR body and passed it off as its own, the digital SLR field has grown tremendously. It's the de facto standard for all photographers worth their weight in developer fluid. Working like a regular single-lens reflex camera, light enters the lens, reflects off the pentaprism, and hits the image sensor instead of film. DSLRs brought down the cost of being a photographer, making dark rooms, sadly, a thing of the past.