On new DSLRs the focus button is paired with the shutter release in a two-stage button; pressing halfway down will activate the focus, and a full press will take the picture. This combination can be fine for most occasions and everyday life events. Separating the focus button from the shutter to a dedicated button on the back of your camera is aptly named back button focus, and has great benefits.
When trying to capture that critical moment having your finger half pressing the shutter is less than ideal and can cause camera shake from your hand cramping. Furthermore, it allows for the ability to set focus with one button, then shoot with the other when the moment is right. If you focus with the shutter release button, say, on a bride, and then someone walks in front of the lens the focus will shift, but you don’t have that issue with back button focusing, and that’s just one reason.
Back button focus makes focus and recomposing simpler, and you don’t have any accidental exposures when in the middle of a recomposition. Using the technique allows you to more easily capture motion in the street, sports or wedding photography with your AF-C (auto focus continuous) mode. In a recent post on CreativeLive, photographer & CreativeLive instructor, Mike Hagen, shows how to set up back button focus on Nikon camera while giving a few examples of the benefits.
Back button focus can be beneficial to your photography if your camera supports it. I know for Fuji shooters back button focus isn’t implemented in the came way as Canon, Nikon, and Sony; the work around can be a little flaky at times. If you haven’t set up you camera to use back button focus, give it a try. As you begin to use your camera more and more, you may wonder how you have ever lived without it.