What is Aperture?
Aperture is the hole that lets light into the camera. Mostly the aperture is just part of the lens, but sometimes it features as part of the camera as well. You could think of the aperture of the camera like the pupil of an eye, it can constrict to decrease how much light gets through, and expand to allow more light through.

As I’ve talked about on other posts, light is what creates a photograph. Aperture is one of three ways you can control how much light gets into your camera, the others being ISO and Shutter Speed. In this post I will talk about when and why you might want to use specific apertures.

Aperture is measured in ‘F stops’. Lenses vary in terms of their aperture range. A lens with an option for a large aperture, such as f1.4, is known as a ‘bright’ lens, because it is capable of letting a lot of light in. Some examples of F stop numbers can be found below, with each increment shown here the aperture is halving in size.

It can be confusing at first to remember which F stop refers to what size aperture, but try and remember: 

  • the smaller the number, the bigger the aperture 
  • the bigger the number, the smaller the aperture

Depth of field
As well as being one of the ways you can control how much light is allowed into the camera, aperture has another effect that you can utilise. You can use your aperture to dictate the ‘depth of field’ in your photograph. Depth of field refers to how much distance within the scene you are photographing will be in focus. Depending on the aperture you choose, there will be an optimum field of focus. See diagram below.

How do I decide which aperture to use?
Often in portraiture photography, it’s nice to have a really sharp focus on the subject’s face, and a really blurry background behind them. That way the viewer's attention is drawn to the main subject of the photo. To achieve this effect you need to select a large aperture, e.g. between f1.4 and f2.8. See an example of a photograph taken using a large aperture below.


If you are photographing a landscape, you probably want most of your image in focus, so you can see the detail of things that are both close to and far away from the camera. To do this you’d need a small aperture, something between f16 and f22. See an example of a photograph taken with a small aperture below.



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