From a landscape under the scorching sun in Death Valley to a football game in a dimly lit stadium, photographers take pictures in a wide variety of settings. No one film is just right for all of the situations photographers find themselves in. That is why there are many films speeds and types. Selecting the proper film is an important step in taking professional quality pictures. By matching the film to the job, you can get the best possible pictures.

Film speed is an important part of film selection and can determine how successful your photographs will be. When selecting which film to use, you must decide what you want as an end result. Do you want to have slides or prints? If you want prints, do you want your prints to be in color or black and white? Once you have decided on the type of film, you will have a range of film speeds available to you.

Film speed is based on an ISO number. ISO is short for International Standards Organization, the group that set the standard. You may have a camera manual which makes reference to ASA (American Standards Association) or DIN (Deutsche Industrie Norm). Those designations are no longer in use, though ASA settings are identical to the currently used ISO standards. The most commonly seen are ISO 25 to 3200. The lower the ISO number, the less sensitive the film is to light. It takes longer to expose film that is ISO 25 than film that is ISO 100. Film with a low ISO number, from 25 to 50, is said to be “slow film” because of the slower shutter speeds required to photograph when using them. Film with an ISO from 64 to 200 is called medium speed film, while film with a rating of ISO 320 or higher is often referred to as “fast film” because it can allow for faster shutter speeds under less than ideal conditions. The benefit behind using slower films, such as ISO 50, is that the resulting prints or slides are exceptionally sharp. Graininess is least apparent in pictures taken with a low ISO number film, that is properly exposed in good lighting conditions. By choosing the slowest film suitable for your photography, you can get the best possible prints. The rule of thumb for most snapshot-type photography is that you should use ISO 100 film for pictures taken indoors with a flash or outdoors in bright light. ISO 200 film is for general purpose photography with a mix of flash and available light and ISO 400 is for sports or low light pictures without a flash.

This is the advice that you will get at most any camera shop when asking about which print film to use. It is good advice for beginners, but it is not all you need to know about film speed. The above advice doesn’t take into account all of the factors you should look at in determining the film speed to use. I have had a lot of success photographing sports such as whitewater kayaking or football using ISO 64 film. It limits my photography to only sunny or bright overcast days, but I am able to take the quality of pictures that clients expect without having to use a fast film. It keeps the grain fine and allows for a good deal of enlarging. If you want to photograph fast moving subjects using a slow film, such as ISO 50, be sure to carry along some faster film as a backup. I always have an assortment of film types and speeds on hand to take care of unexpected conditions. The other important point that the general advice on film speed fails to take into account is that grain can be beautiful. With the right subject, a grainy photo can lend just the right feeling to the final print. French photographer Sarah Moon made a name for herself with fashion photography that used apparent grain as an artistic effect. Perhaps you are taking photos in bars and could get by with ISO 400 film and a tripod, but the effect you want might be better achieved with ISO 3200 speed film. The grain in the photo could give the print the sense of the subject in a way that a fine grained print can’t. If you want to end up with a grainy photograph, you will want to start by using a fast film, such as ISO 400 or higher. You may also want to “push” your film.

“Pushed” or “Pulled” Film Speeds
The ISO rating given to the film you buy is an optimal film speed and is the setting to use when the film will be processed normally according to the manufacturers directions. You can “push” or “pull” your film by setting your camera at a different ISO rating from the films rating and process accordingly. ISO 100 film exposed at ISO 200 is said to be pushed one stop, because it would take an extra f/stop to expose the film identically. So a photograph that could be taken at f/2.8 for 125th of a second on ISO 100 film, could be taken at f/4 for 125th of a second if the film is pushed one stop. The film would then be exposed at EI 200. That indicates that the film was exposed at ISO 200, but shows that value is one you selected. By pushing your film and processing accordingly, you can photograph in lighting conditions far from ideal. As a newspaper photographer, the wide latitude available by pushing Tri-X film saved me on many a Friday night as I photographed high school football games in stadiums with poor lighting. I generally used an EI 1600, but occasionally had to push film to EI 3200 long before Kodak offered a film with an ISO that high. Push processing works best with black and white or color slide film. Pushing color negative film, in my experience, gives disappointing results. No matter what film type you use, best results are obtained by using the highest film speed possible, and then only pushing it if you must. For example, better results can be obtained by photographing ISO 400 film at EI 400 than from pushing ISO 200 film to EI 400. Film which is exposed at an ISO number half that of the manufacturers rating is said to be pulled one stop, such as ISO 400 film exposed in a camera set at ISO 200. This particular technique was one favored by Ansel Adams who routinely shot ISO 400 Tri-X film at EI 200. He favored the way the film worked when pulled one stop. It is important to remember that pushing or pulling the film is not just a matter of adjusting your light meter. The film must be processed properly. Many labs offer push and pull processing services for an additional fee. Check with your lab before you shoot. Push processing is not the only reason to alter your camera’s ISO setting. You can increase the color saturation in your slides by setting your camera one click higher than the manufacturers suggested ISO, such as ISO 125 for ISO 100 film. That will underexpose your slides by 1/3 of a stop. The effect is very pleasing with many slide films. Understanding film speed is an important step in learning to improve your photography. By selecting the best film for the photographic task at hand you can get the best results possible from everything you shoot.

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