Back Button Focus

What is back button focus and how can it be used?

As standard when you receive your new camera, the shutter button will not only take the picture but also control the metering and the focusing.

With back button focusing, we remove the focus element from the shutter button and move it to the AF-ON button on the rear of the camera.

Once set up, what this does is give us the flexibility of auto focus, focus lock and manual focus just by either holding the back button down or releasing it. While the button is depressed and we are in AI-Servo mode, the camera will constantly focus on the subject. As soon as we release the back button the camera will then lock focus and also allow us to manually adjust if required or to recompose our image.

Let’s imagine a bird in flight, keep the back button held down whilst we track the bird and focus will be maintained, whilst we use the trigger button to capture the subject without effecting the focus.

Now let’s imagine the bird lands in a tree, we can still hold the back button down even though the subject is stationery to maintain focus. However, if there are branches or leaves blowing around the subject the focus may be disrupted by those surrounding items. In this case we focus on the subject with the back button, and once we have the focus established we can release the back button and the subject will remain focused even if something moves across the front. This also allows us to recompose the image without loosing the focus from the subject.

That gives us an overview of “back button focus” but to see how we set the camera up and use it, make sure you watch my video tutorial below.