Use the right film to help achieve your photographic goals.
Negative film is usually used for making prints. Reversal film is usually used for making transparencies or slides. Digital images can be made by scanning either type of film.
Reversal film is considered to have an advantage for capturing colors accurately. Negative film gives you more leeway in setting exposure and can provide more detail in high-contrast lighting.
Films vary in their sensitivity to light, as expressed by their ISO film speed. The higher the ISO number, the “faster” the film and the less light you need to take a picture.
Fast films of ISO 400, 800 and higher are recommended for dim lighting or fast action such as sports photography. A fast film lets you use a high shutter speed to “freeze” rapid motion and minimize blurring with handheld shooting or telephoto lenses.
Slow films in the ISO 100 range are ideal for brightly lit situations such as outdoor sunlight or studio photography. In portrait photography, for example, a slow film allows a wider aperture (lower f-stop number) to defocus the foreground or background. A tripod lets you take full advantage of the fine granularity of slow films without worrying about blurring.