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 Shutter Speed? What is Exposure? What is Aperture? 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?
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.
F2
F2. 8
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
What is Shutter Speed?
What is Exposure?
What is Aperture?
2025-8-3 17:00