Photography cheat sheet: How to understand ISO settings

Canon camera with ISO settings
(Image credit: Future)

The ability to adjust your camera's sensitivity (ISO) is one of the great advantages of digital capture. Unlike with film cameras, you can change the ISO for every shot with ease, should you wish to. But when and why should you change this fundamental photographic control, which, along with aperture and shutter speed, makes up part of the exposure triangle.

But what is ISO, exactly? Changing your ISO setting means that you can tailor the camera to various situations. Doing so will help you to end up with an image that's sharp and appropriately exposed, whatever the environment.

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Chris George

Chris George has worked on Digital Camera World since its launch in 2017. He has been writing about photography, mobile phones, video making and technology for over 30 years – and has edited numerous magazines including PhotoPlus, N-Photo, Digital Camera, Video Camera, and Professional Photography. 

His first serious camera was the iconic Olympus OM10, with which he won the title of Young Photographer of the Year - long before the advent of autofocus and memory cards. Today he uses a Nikon D800, a Fujifilm X-T1, a Sony A7, and his iPhone 15 Pro Max.

He has written about technology for countless publications and websites including The Sunday Times Magazine, The Daily Telegraph, Dorling Kindersley, What Cellphone, T3 and Techradar.

With contributions from