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Graininess of film

If there is no grain, there is no picture


GRAIN IS NOTICEABLE IN THE NEGATIVE (OR SLIDE), NOT THE FILM

The light-sensitive emulsion of film contains numerous minute crystals of silver halides which react when exposed to light. The crystals are called grains. The term “graininess” as applied to film is thought by many people to mean an accumulation of these crystals, but these little, individual grains are much too small to be seen by the naked eye, and are not the grain we see in pictures. In fact, they would have to be enlarged about 50 times in order to see their structure. They are the beginning of graininess, though, since they are transformed by development of the film into tiny particles (clumps, really) of metallic silver, and “graininess” refers to these clumps that form a negative or a slide.

The darker (or denser) parts of the negative have more of these clumps layered together than the negative’s more transparent parts. When making a print, light is shined through the negative onto light-sensitive paper. The denser parts of the negative block more light than the more-transparent parts, and therefore they show up as a lighter tone on the finished print. The result is that dark areas on the negative appear white on the print, and vice-versa, making a positive (reflecting the true tones of the subject) from a negative.

If the clumps of individual grains are large and irregularly spaced out in the negative, they can become visible to the naked eye in the finished print, more so in enlargements. When this occurs, the picture appears “grainy.”

This greatly-enlarged and cropped image shows the grain in 35 mm ISO 100 film.
This greatly-enlarged and cropped image shows the grain in 35 mm ISO 100 film.

THE EFFECT OF GRAININESS

The effect of graininess is usually more visible in medium-gray shades in black and white film and in the lighter to medium tones in color film, and is most apparent in out-of-focus areas of the picture. Texture suffers when the film is grainy, accutance is low (meaning that edges are less clearly defined - making pictures appear to be less sharp), and fine lines tend to look blurry due to the softening effect of enlarged grain. It may help you to understand how this occurs if you can imagine two frames of the same size, say about 2 feet by 3 feet - one filled with small, round pellets, like BB pellets, and the other filled with golf balls. If the pellets were painted different colors that were carefully arranged to form a picture, it would have a great deal of detail, but if you colored the golf balls and made the same picture, it would lack much of the definition of the picture made with the smaller pellets. This is the effect of graininess in negatives, although not as exaggerated.

FACTORS AFFECTING GRAININESS

Grain is usually greater in overexposed film than in negatives that have been correctly-exposed and developed.

The sharper the image is on the negative, the less obvious is its graininess.

Development time can affect a negative’s graininess. Graininess increases with longer-than-normal contact with a film’s developer before development is stopped, and decreases with shorter-than-normal development times. This makes sense, really, if you consider that the function of a developer is to clump together the tiny silver halide crystals in the film. The longer the film is in contact with the developer, the more clumping will occur, hence the increase in graininess. The problem with achieving finer grain from slower-than-normal development time for a particular film is that the resulting negatives usually have lower than normal contrast. There is always a trade-off, isn’t there?

Film developers are available that will produce finer grain than standard developers. These are called, not surprisingly, “fine grain” developers. But, many of these fine grain developers are meant for films that have been “pulled” by the photographer (i.e. shot at a lower film speed than the manufacturer’s rated speed - for example ISO 100 film exposed at ISO 50) and will not have much visible effect on a film exposed at its rated speed.

ENLARGEMENTS SHOW GRAININESS MORE

If all of your prints are 3” X 5" or 4" X 6" in size, you will not see much difference in graininess among most of the different speeds of film. As you enlarge your negatives, the grain becomes more apparent. Most films, even the very fast ones (e.g. ISO 3200), will produce a fairly-decent 8" X 10" enlargement that shows sufficient detail in low contrast pictures, but the graininess of fast films becomes quite visible in big enlargements made from small-size film.

Larger film sizes need less enlarging to produce the same-size enlargement, and therefore their grain shows less. This is one of the big advantages of medium-format and large format cameras.

The paper used in printing enlargements can also affect the graininess of an image. If it is high-contrast paper, you will see more graininess, and pictures printed on low contrast papers appear to have finer grain.

ALL FILMS ARE GRAINY; FAST FILM IS GRAINIER

Grain is part of film. Slow speed films have finer grain (like the BB pellets) and the film’s granularity generally becomes greater with increases in film speed. The faster the film, the coarser its grain structure.

If you wish to capture detail and texture in an image that is as close as possible in appearance to your subject, then fine grained (slow speed) film is your answer. If your image will benefit from the softness and reduced definition of larger-sized grain, or if you must sacrifice fine definition for film speed because of shooting conditions (low available light being the typical primary reason), then fast film will meet your needs.

Since grain is not derived from the subject, but comes from the film you use to photograph the subject, you should try to minimize visible grain in your images by selecting the least-grainy film for most of your photography, based on shooting conditions. We say “most of your photography” because sometimes the graininess of very fast films can be exploited to create mood and inherent softness in your pictures. In most cases, however, you will want the least graininess possible.