The standard size for both motion picture and still photograph film is 35 millimeters (mm) wide. As their name indicates, 35 mm cameras are manual cameras that use this standard size of film. Although 35 mm cameras have mostly been replaced by digital cameras, many photographers still use them because they are the classic choice and because they offer a different level of control over the finished product.
Two basic types of 35 mm cameras exist. Lens-shutter cameras are often called point-and-shoot cameras. They are small, quiet, and easy to use. The photographer views the scene to be shot by looking through a window set into the camera. This system allows the photographer to have a general idea of what the photograph will look like but does not allow for exact focusing and composition.
Greater control is offered by the single-lens-reflex, or SLR, camera. These 35 mm cameras tend to be bulkier than the point-and-shoot variety. The photographer is able to buy various lens attachments for the camera, such as zoom lenses or wide-angle lenses. To view the subject, the photographer looks through a viewfinder. A system of mirrors allow the photographer to see the exact image framed by the lens. This allows for accurate focus and composition adjustments.
Thomas Edison developed 35 mm film in an attempt to find the perfect film for motion pictures. Edison needed a film that was compact enough to run through a reasonably sized piece of projection equipment but not so large that adequate light could not be shined through it to create the projection. A version of this standard-size film was adapted for still photography.
Films of all types are created by coating thin plastic with a light-sensitive chemical emulsion. As light comes through the lens of the camera, it causes reactions in the chemicals on the film. The brighter the light or the longer the film is exposed to light, the darker the resulting image will be. The image becomes visible when developed into a negative, which is then used to make a positive print.
All camera films are rated based on their speed. Low-speed films are less light sensitive, while high-speed films are more light sensitive. Faster films have larger chemical grains, resulting in larger pixels on the final image. The larger the grain, the more likely it is that the resulting image will be grainy. Photographers choose film speed based on lighting and the subject they will be shooting.