What does DX coding on a film communicate to the camera?

DX coding on a film communicates important information to the camera, specifically the sensitivity level of the film. This coding, which consists of a series of perforated notches on the film cassette, allows compatible cameras to automatically set the appropriate exposure settings based on the film's ISO rating. Cameras can then adjust shutter speed and aperture to ensure optimal exposure.

Understanding this, sensitivity levels are paramount when using DX-coded film, since they directly affect how the camera interprets light and other ISO-related settings. The other options do not accurately represent the functionality of DX coding. Film type and aperture size are not indicated through DX coding, as film type refers to characteristics such as color or black-and-white film, while aperture size is a lens-related specification that determines the amount of light entering the camera and is not influenced by the film’s DX coding.