This video is part of our Intro to Photography series, where we break down some of the fundamental concepts of the image-making process. You can find a written version below.
Intro to Exposure
What is aperture?
Aperture value is one of the fundamental aspects of exposure and perhaps the most intimidating, but it needn’t be. The easiest way to think about it is as the name of the size of the hole through which your camera sees the world. A bigger hole lets in more light, and a smaller hole lets in less.
Why are aperture numbers in that sequence?
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| At first, it can be hard to grasp the aperture scale, since it goes 1.4, 2, 2.8, 4, 5.6, 8, etc. |
The naming system can seem confusing at first: aperture settings are named for what fraction of the focal length the diameter of the hole is. This risks being confusing in two ways: firstly, a smaller number represents a larger hole, and, secondly, the pattern relates to the square root of 2. Most people won’t be able to spontaneously think in terms of root 2, so your best bet will be to memorise them.
How does aperture affect exposure?
The key thing to learn is that changing your aperture value by a whole’stop’ lets in double or half the amount of light, in just the same way that doubling or halving your shutter speed does. With time, you’ll come to remember that F2 is a whole stop brighter than F2.8 and that F4 is another stop less bright.
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| F2 | F2.8 |
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| F4 |
This is why lenses with very large apertures are typically so much larger and more expensive than lenses that aren’t as bright.
As well as letting in more light, to give you better image quality in low light conditions, a wide aperture will also give you shallower depth-of-field, and blurrier backgrounds. But that’s a story for another day.
Intro to Exposure
Our DPREVIEW Tribute:
After nearly 25 years of operation, DPReview closed on 10 April 2023. This difficult decision was part of the annual operating plan review that parent company, Amazon, shared earlier this year.
Over the course of 25 years, DP Review built up a reputation as being one of the most informative places to go for information about that new camera or lens you’re after. DP Review began as an independent reviews site based in the UK in 1998, the brainchild of Philip and Joanna Askey, but it was eventually purchased by Amazon in 2007 and relocated over to Seattle in the USA in 2010.
Cheers DPReview – thanks for the great work and content that guided photographers, videographers and techno junkies the world over!
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