Digital Camera Photography Exposure Latitude: Digital Cameras Basic Theories

The third variable element depending on the sensitivity of the film being used is the grain , meaning, the more or less granulated aspect of our prints. All emulsions are made up of microscopic silver halide crystals. The developing forms accumulations of silver through the decomposition of the crystals. Any of these accumulations can be considered the minimal density unit, and is comparable to a peace of a giant mosaic made up of millions of them, and whose size is variable .

The greater the size of the grain, the more visible it is in the print, specially in large prints; the more grain, the less sharpness and fineness of detail, because it is like a mosaic made up of larger pieces. Therefore, when the grain is fine, the image is very sharp, has good fineness of detail and a minimal grainy aspect. The size of the grain depends on many factors:

•  The sensitivity of the film: Low sensitivity emulsions have fine grain and those of high sensitivity, heavy grain.

•  The exposure level and resulting density. Since grain is the aggregation of metallic silver particles, and density is the accumulation of grain, the greater the density of a negative or one of it's zones, the more grain we will be able to see, specially is the zone is reflected in the print not as a white tone, but a medium brightness gray. A medium tone in the copy has much more grain if correspondent zone in the negative also has a high density. High densities in the negative normally correspond to the lights of the scene, which will appear white in the print, and there, with no visible grain. As we have seen in the example of 4.3.1.2, when the contrast of the scene isn't excessive and we have various exposure options, when adjusting to the left of the latitude we are able to minimize the size of the grain and therefore maximize the sharpness. It isn't necessary to place the scenes brightness interval higher on the density ladder because that only causes a decrease in the fineness of the grain. On the other hand, if for a specific photograph we want an effect with high grain, the exposure level should be abundant, adjusting to the right of the latitude, because this way we will get the medium brightness of the scene, which in the copy will be gray tones, to appear with greater density in the negative, and therefore, more grain.

•  The type of developing: we can develop in a way that reduces the minimal size of the grain or also an intense developing to increase the sensitivity of the film, which mean a large increment of said size.