Denotes how sensitive a film is and is calibrated in ISO numbers. High number ISO films are effective in poorer light situations than lower number ISO films but produce aesser quality. Focal length . Underwater, lenses have a narrower view than in air, so a lens of 35mm underwater has the same 52angle as a standard lens of 50mm might have in air. The ability to bring a subject into sharp focus.
Some simple cameras have 'fixed-focus' lenses set at an arbitrary 'most useful' setting.
The size and shape of the original picture made by the camera, and the type of film used. Small format 35mm cameras use motion picture-type film of 35mm gauge, making an image size 24mmx36mm. O-rings are used to make watertight seals. They should be clean, free of any breaks or defects, and lightly lubricated with silicone grease. The window through which a camera looks from a marine housing.