A fundus camera is used to take images of the retina, which is the back portion of the eye. Basically a microscope with a camera attached, images of the retina are taken at different angles of view and magnifications depending on what the doctor needs, and can be used by practitioners to diagnose certain eye diseases. A 35mm Fundus Camera uses a 35 mm format, which refers to a 36x24 mm digital photographic film format.