Film Grain 101
If you have taken an interest in film photography, one of the aspects that may have attracted you is the ‘’aesthetic.” That is, how pleasing it is in appearance to which a lot of people attribute to the vintage, raw and natural finish of film as opposed to digital. A huge part of this is down to grain.
What is Grain?
Baked into the emulsion of a film negative are silver crystals which are the light-sensitive halides that transform into metallic silver when exposed to light. This is what allows us to capture images with film and therefore why grain exists in every image ever captured on film. You will notice this grain as speckles, not always uniform, across the image.
The final appearance of these silver crystals as grain in your images will vary based on the speed (ISO) of the film you choose.
If you want to minimise the amount of grain – resulting in sharper images – you would opt for a slower speed film in which the silver crystals within the emulsion are smaller. Keeping in mind that this means that the film’s light gathering ability is very low, so you would need a well-lit scene in order to adequately expose your images and in some cases, a tripod for stabilisation so you can slow down your shutter speed.
If more grain is the goal, then you would be looking for fast film stocks where the crystals are much larger and therefore able to gather more light. Unfortunately, 800 speed is what we are limited to in colour emulsions nowadays (Portra 800 and Cinestill 800T) however in black & white we can reach up to 3200 (Delta 3200 and T-Max 3200).
Of course, exposure is going to play a key part in achieving the level of grain you prefer. If your setting means the film is underexposed, those light gathering particles are working overtime to attempt to pick up information, but if there just isn’t enough light, you will end up with a lot of grain in the shadows.
In underexposing any roll of film, you are likely to see an increase in grain for that very reason; the film is struggling to expose for the shadows and where it can’t, you will see that heavy presence of grain. This is why sometimes you might be shooting a 400-speed roll and end up with grainier images than you would expect – you would have been shooting in lower light conditions than usual and the film had to compensate.
Overexposure can have a similar affect in the highlights and midtones of your images.
More grain = higher ISO = more light gathering ability
Fine grain = small ISO = needs more light to expose