Film Grain: What Causes It and How to Control It

Grain is the visible texture of a film image, and for many photographers it is part of the reason to shoot film. It comes from the structure of the emulsion, but how much you see depends on the film, the exposure, the developer, the format and, today, the scanner. All of those are things you can control.

What grain is

In black and white film, the image is made of clumps of developed silver. Individual silver grains are far too small to see; what we call grain is the random clumping and overlapping of many of them, visible as texture in even tones. In color film, the silver is removed and the image is made of dye clouds that form around where the silver was, giving a softer, more diffuse texture.

Film speed and grain

Faster films need larger crystals to catch light, so higher ISO means coarser grain. ISO 100 film looks smooth in an 11x14 print from 35mm; ISO 3200 film shows strong grain even in small prints. Modern tabular-grain films such as T-Max, Delta and Acros II use flat crystals that capture light efficiently, giving finer grain than traditional films of the same speed, such as Tri-X or HP5 Plus.

Exposure and grain

Grain is most visible in the midtones and in areas of even density. In black and white negative film, underexposure followed by extra development, as in pushing, produces the most visible grain, while moderate overexposure increases density and grain slightly. In color negative film, underexposure makes grain dramatically worse, because the scanner or printer has to lift thin shadows. A little overexposure usually gives the cleanest result.

Development and grain

Fine-grain developers such as D-76 stock, Perceptol or Microdol-X soften grain at a small cost in sharpness or speed.
High-acutance developers such as Rodinal render grain sharp and crisp.
Longer development and higher temperatures increase grain.
Pushing increases grain and contrast.

See film developers explained and push and pull processing.

Format and enlargement

Grain size in the film is the same whatever the format, but a smaller negative has to be enlarged more for the same print. A 6x7 negative needs about a third of the enlargement of a 35mm frame for the same print, so grain looks much finer. That is why ISO 400 film in medium format often looks as smooth as ISO 100 in 35mm.

Scanning and grain aliasing

When a scanner's sampling grid is close in size to the film grain, the two interfere and create a harsher, exaggerated pattern. This is grain aliasing, and it is why some scans look grainier than a darkroom print of the same negative. Scanning at a higher resolution, or slightly defocusing a camera scan, can reduce it. Heavy sharpening in software also exaggerates grain.

Seeing grain at full resolution

Online images are usually downsized, which hides grain. Members of FilmPhotography.com can attach a full-resolution crop of the original scan when uploading a photograph, so you can see the real grain of a film and developer combination at 100 percent.