Some high-end DSLR cameras are very flexible, allowing the photographer to customise the function of many of the buttons so that the camera operates just how you wish. If you have such a camera, you can take advantage of this functionality by enabling back button focusing.

What is Back Button Focusing?

Many wildlife photographers choose to control the light meter, image stabiliser and shutter release with one button, whilst activating autofocus with another. This is what we mean by the term back button focusing. This technique got its name because the autofocus button is on the rear of the camera body. Back button focusing works very well when you’re photographing birds in flight because this is exactly the sort of control you need when tracking a subject that is moving erratically.

Advantages of Back Button Focusing

Once you have set up back-button focusing, you can activate or deactivate the autofocus system with your thumb. The light meter and image stabiliser can be activated with your first finger, just as before. You can now use these controls independently, or in unison. By being able to activate autofocus independently of the light meter, you can set and check your exposure without having to acquire focus on the subject at the same time.

Back button focusing also allows you to deactivate the autofocus system whenever you lose track of your subject. You should always do this when using the AI Servo focusing mode, to prevent the camera from focusing the lens on the background and becoming grossly out of focus. This set-up also allows you to choose when to keep the image stabiliser active, which helps reduce visible wobble when you’re trying to locate your subject through the viewfinder.

How to Enable Back Button Focusing

If you use a Canon EOS 1D Mark III or a Canon EOS 1D Mark IV, you can find detailed instructions on how to enable back-button focusing in my guide to Canon EOS 1D Mark IV custom functions. The same instructions work for both camera models. Back button focusing is also available on the Canon EOS 1D Mark II and Mark IIn variants, and on many Nikon cameras. If you use one of these cameras, please send me instructions on how to set back button focusing up on them so that I can add them to this page.