Photographic film Uses
Film can only be used once. After that, it cannot be used again. When not in use,  the film needs to be covered from light, otherwise it will record any lights that shine on it. This will make it useless to record a picture later on. Film comes in a can called a canister to cover it from light rays. Film needs the right amount of light to make a picture. If the picture is too bright or too dark, it will not record correctly. The longer that the film keeps recording, the more light it will get. If what is being photographed is bright, it will be recorded faster. If it is darker, the film will need more time to record. Different speeds of films are marked with an ISO number.