It can definitely be confusing.

For example, traditionally still film cameras used 35mm film, but cinema cameras also used 35mm film. However the cinema cameras capture the image vertically instead of horizontally on the film, otherwise known as a Super 35. Literally the film runs through the camera vertically instead of horizontally.

In order to make an image work that is understandable to our brains you either need to do heavy cropping and waste tons of film, or you use an anamorphic lens to "squeeze" more light onto the film. You then have to reverse that when you go to project the film.