Make ISO work for you

1 What is ISO?

Originally ISO related to film speed; it refers to the sensitivity of the emulsion to light. Digital sensors work in a similar, but different way. With digital sensors, when shooting at lower ISO settings the sensor appears to be less sensitive to light and image quality is better, while at higher settings noise becomes more apparent as the sensor becomes more sensitive to light. The reality, however, is that digital cameras have a single base ISO setting, which is often ISO 100, and when increased or decreased, a software algorithm simulates an effective sensitivity of the sensor.

2 Test your camera’s ISO performance

The best ways to identify the highest ISO setting you're happy to use is to do an ISO test. Set your camera up on a tripod in aperture-priority mode and take a series of shots at all the native ISO settings. Shoot in raw and load the images into Lightroom or your preferred raw-editing software and make sure all noise reduction is switched off.