Photography cheat sheet: diffraction, aperture and resolution explained

photography cheat sheet: diffraction and aperture
(Image credit: Future)

Altering the f/number does not just alter the amount of light reaching the sensor. The aperture is one of the main factors affecting the depth of field, and how much of the scene actually appears sharp. The aperture that you choose for a particular shot will therefore depend on which parts of the scene (if any) you are prepared to appear out of focus – and on the shutter speed you need to use (the faster the shutter speed needed, the wider the aperture will need to be, if you are going to leave the ISO unchanged). 

However, there is another factor that you need to take into account when choosing your aperture: a lens will perform better at some f/numbers than others, and it won’t give its best resolution when set at its maximum aperture. 

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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.