LESSON 17
Film stocks
Speed, grain and colour: what the name on the box tells you before you load the roll.
GRAIN · ENLARGED
- SlowISO 100 · FINE
- MediumISO 400
- FastISO 800 AND UP · COARSE
Three grey squares with dots of increasing size: fine grain for slow film, coarse grain for fast film.
Speed and grain
A film's speed comes from the size of its light-sensitive silver halide crystals. Larger crystals catch light more readily, so faster films show coarser grain, while slower films are finer and hold more detail.
Negative, slide, black and white
Colour negative film is the forgiving one: it tolerates more over- and underexposure than other films. Slide film gives a positive on the film itself, with more contrast and fewer stops of latitude. Black-and-white film usually has a single layer of silver halide.
Three stocks, compared
The figures below are the makers' ratings as recorded on Wikipedia, not our tests.
| Film | Type | ISO | Known for | Since |
|---|---|---|---|---|
| Kodak Ektar 100 | Colour negative | 100 only | Fine grain, strong colour | 2008 |
| Kodak Portra | Colour negative, daylight | 160, 400, 800 | Made for portraits and weddings | 1998 |
| Kodak Tri-X | Black-and-white | 400 (320 in sheets) | Among the fastest black-and-white films | about 1940 |
Daylight and tungsten
Film is made for a kind of light, most often daylight or tungsten. Under household bulbs, daylight film turns warm unless you put a correcting filter over the lens or the lights.
Processing
Colour negative is developed in the C-41 process, introduced by Kodak in 1972 and the most widely used film process today; nearly every lab runs it.
Try it today
- 01Buy one roll of colour negative and one of black-and-white, both ISO 400.
- 02Shoot both in the same places, bright and dim.
- 03Give a few frames one stop more light than the meter says.
- 04Have both developed and scanned.
- 05Compare grain and shadow detail side by side.
Figures from Wikipedia, 'Photographic film', 'Film grain', 'Film speed', 'Reversal film', 'Ektar', 'Kodak Portra', 'Kodak Tri-X', 'Color temperature', 'Color balance' and 'C-41 process', read 2026.10.16. The steps under Try it today are working practice, not a standard.