Take your best shot

Why is ISO so important?

By Adrian Toon, director of a2n.

If you have a phone camera you may have come across the setting for ISO. If you have a digital camera it will be a setting you will have seen, but what is it?

ISO stands for ‘International Organisation of Standardisation’. Yes, the same organisation we all know and love?

It is a measurement for the sensitivity of a film emulsion, or these days a digital camera sensor. Used in both stills photography and video, the ISO is an important setting to understand.

Years ago, I used to use ‘Kodachrome 25’ film for commercial work, a ridiculously low ISO of just 25. The lower the number the less sensitivity of the sensor, but with less sensitivity we get higher quality.

The norm these days is for a digital sensor to start at 100 ISO and then increase to 32,000 or more, which helps the camera to work in lower light levels. Electronically increasing the sensitivity of the sensor reduces its quality and often produces what is known as ‘noise’, or what would have been called ‘graining’ on film.

When taking images for PR, try to keep to a low ISO, which keeps quality in the image. Often a setting of 400 or 800 is adequate, but like everything I discuss here, try it out, experiment, zoom into images taken at different ISOs, and decide what setting you are happy to work with as each sensor varies.