About Film

Photographic film is where the information you capture will be stored. Thus it is necessary to know about it at least a bit.

Generally spoken, there are three different sorts of film: black-and-white film, print/colour negative film, and slide/chrome/transparency film. Black-and-white film contains silver halid which changes its state when the film is exposed to light. These films are always sharper than comparable colour films, and you can rather easily develop them on your own. Print film consists of several light-sensitive layers. They are less sharp than comparable black-and-white films, but today in most cases sharper than comparable slide film. They are designed to give optimum colours when printed onto photographic paper. Slide film is designed to be projected. Its big advantage are the powerful colours which make up for the disadvantage of low resolution. On the other hand, prints from slide film are rather difficult to obtain in acceptable quality. So you should think of your use for the film before you select and expose it. A special sort of film is infrared film. These films are very sensitive to red - and infrared. With a deep red filter, you filter all the other colours thus only infrared light will be captured on the film. Skies get dark, foilage light - a very mystic impression.

The three best-known film manufacturers are Agfa, Fuji, Ilford and Kodak. Ilford is a black-and-white specialist, Agfa were leading in the development of colour films before WWII when Kodak were given their patents as war reparations. Today, Agfa, Fuji and Kodak are equally important in colour photography. Agfa have also recently developed a black-and-white slide film, the Scala 200x.

A chapter on its own is Polaroid film. That company whose name derived from its initial manufacture (polarising glasses) developed an instant film decades ago; or should I say their ingenious founder Dr. Land. There are two sorts of Polaroid film, no-waste film and peel-apart film. No-waste film is used for Polaroid consumer film, peel-apart film where the (unusable) negative with a toxic caustic paste has to be thrown away is used for Polaroid professional film. However there is one peel-apart film which also produces a regular negative. There are Polaroid backs for most medium format cameras and Polaroid holders for large format cameras. They use the professional peel-apart film, while the well-known classic Polaroid cameras use the no-waste consumer film.

Black-and-white film is also the most abusable material available. You can use it years after their expiration date (print and slide films can be refrigerated or frozen to last some months or years longer, but errors are much more probable with them), and it generally has a broader exposure latitude than colour film. That means that the shadows and the highlights have more detail - and you also can make some errors in exposure determination. Slide film only has an exposure latitude of about half a stop. It also cannot accomodate large contrasts without producing either white or black image areas.

Each film has a sensitivity, or "speed". The measure for that are ASA units (called ISO in the past). A standard film has 100 ASA, a high-speed film up to 3200 ASA, a slow film down to 25 ASA. The advantage of film speed of course only can be obtained with a disadvantage: The faster the film, the bigger the accumulations of the emulsion (the "grain") get. This creates an effect of unsharpness. Print films above 400 ASA and slide films above 100 ASA are not very good even today. Black-and-white film is more forgiving.