Grain in Film Photography

Grain is defined as

  • the subjective salt-and-pepper appearance of a negative, slide, or print resulting from clumps of metallic silver or clouds of color dyes congregating together in the image.

  • Generally, grain is most apparent in the clear mid-tones that lack much pictorial detail.
     

Information about Granularity

  • Grain is an observable structural aspect of a negative, slide, or print. It is the measured variation in the distribution of an otherwise uniform silver deposit or dye cloud.

  • Grain growth is linked to film speed. As film sensitivity increases, and corresponding ISO numbers go up, so usually does the appearance of grain. We can generalize that faster films are grainier than slower ones.

  • The issue of what is acceptable or objectionable grain becomes important only when an image is magnified sufficiently for the grain pattern to become visible.

  • Color films, print or slide, contain no residual silver in their finished forms because the dyes forming the color image create dye clouds at locations previously occupied by developed silver clumps. Depending on the nature of the former silver inhabitants and the composition of the new color dye clouds, what appears as grain in black-and-white images can be seen in color negatives and transparencies as well.

  • Grain or even dye clouds are not necessarily visible to the naked eye. What we see are not individual grains but groups of grains or dyes at different strata within the emulsion layer of the Elm or print. The degree of visible graininess is also a function of how regularly or randomly the grains of silver are distributed. An observer may not perceive grain in a certain image if it is arranged in a regular, repeating pattern. However, the same observer might see a second image as grainier than the first even though it contains fewer silver particles by actual count-simply because its architecture scattered the silver grains randomly.

  • It has been a long-standing goal of film designers to create emulsions and papers with regular, uniform, and repeating grain patterns composed of identically shaped crystals in an ever-thinner emulsion substrate.

  • It is important to point out that in film design, as in fashion design, thin is good. The thinner the emulsion, the more it can potentially resolve. Also, since thin emulsions tend to cause less light scatter than thicker ones, they can contribute more readily to the perception of fine grain.

  • Color films and prints display what appears to be grain in much the same way that black-and-white material does. However, the manner in which grain-like structures are produced in color films and prints is quite different from black-and-white, but the resulting image-degrading effects are similar for both.

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