technical: What film shall I use?

What film shall I use?

There is a huge and sometimes confusing choice of film on the market, each claiming to be better than the last. Here are a few guiding principles to help you decide what sort of film will suit your needs best.

Film speed

Film speed indicates how sensitive the film is to light. Speed or sensitivity is expressed as a number written on the side of the cassette / film packet. There are several systems that are used, ISO or International Standardisation Organisation being the most useful. The higher the ISO number, the faster the film. So, for example, a film of ISO 400 is twice as fast as a film of ISO 200, which is twice as fast as a film of ISO 100.

In practical terms that means you need twice as much light to take a reasonable photo using an ISO 200 speed film as you do using an ISO 400 speed film, and twice as much again when using an ISO 100 speed film.

Guide to light conditions and film speed

General purpose - medium speed ISO
Outdoors, daylight, bad or overcast weather 400
Indoors, window light and / or bright artificial light 400
Outdoors, sun / cloudy weather 200
Indoors using flash 200
Outdoors bright sunny weather 100

Specialist - very fast ISO
Low light conditions, night photography 1600
Almost complete darkness 3200
Eg. Kodak High speed recording film  

cartoon: a fast hare

Specialist - slow ISO
Studio / artificial light / bright, consistent light 50
Studio / artificial light / bright, consistent light 25
Eg. Kodak Technical Pan  
cartoon: a slow tortoise