Film speed, shown as an ISO number, tells you how sensitive the film is to light. Lower numbers suit bright scenes and give finer grain; higher numbers suit dim light and fast action but look grainier. Choose by the light you expect and the look you want.
What the Number Means
Each time the number doubles, the film needs about one stop less light. Film labeled 400 can work with half the light of 200. In return, higher speeds generally show more visible grain and a little less fine detail, though results depend on the film type and development.
Speed Ranges and Uses
| Range | Typical conditions | Character |
|---|---|---|
| Low, around 50 to 100 | Bright sun, tripod landscapes | Very fine grain, high detail |
| Medium, around 200 to 400 | Mixed daylight, cloud, street | The most flexible range |
| High, around 800 to 1600 | Indoors, evening, moving subjects | More grain, more speed |
| Very high, above 1600 | Dark places and fast action | Strong grain, wide margin |
Questions to Ask
- How bright will it be? Outdoors in the day, a low or medium speed works. Indoors without extra light, move up.
- Will anything move quickly? Fast shutter speeds need more light, so higher film speeds help freeze motion.
- Will I use a tripod? Steady support allows slower shutter speeds, which means you can use finer film.
- How large will I print? Big enlargements show grain more, so lower speeds help.
- Which look do I like? Some photographers enjoy visible grain as texture, especially in black and white.
Color Negative, Slide and Black and White
- Color negative. Forgiving of exposure errors, particularly when slightly overexposed.
- Slide film. Less forgiving, so accurate metering matters more.
- Black and white. Flexible, and development choices can shift the result.
Practical Habits
Carry two speeds if you shoot a mix of settings, such as a medium speed for daytime and a higher one for evening. Set the camera dial to match the film unless it reads the code on the cassette itself. When light is uncertain, giving a little extra exposure to negative film is a common safe habit, since thin negatives lose detail.
Scenes and Suggestions
- Sunny beach or snow: low speed, with a fast shutter if needed.
- Overcast street: medium speed.
- Indoor family gathering without flash: high speed.
- Night city scenes on a tripod: medium speed with a long exposure.
FAQ
Can I shoot film at a different speed than its label?
Yes, this is called pushing or pulling. It changes how the film must be developed, so tell your lab or adjust your own process.
Is lower always better for quality?
Not always. A shaky shot from a slow film looks worse than a sharp shot from a faster one.
The Short Version
Choose a medium speed if unsure, go lower for bright light and large prints, and go higher for dim places and movement. Think about light, subject and print size together.