> 6 minute read

How to Use Back-Button Focusing

Let’s take a look at why it’s a good idea to use this advanced focusing method, what situations it can help you in, and how to prepare

Back-button focusing is a technique used by professionals and serious enthusiasts to add speed and versatility to their photography. It’s simple to do, but takes practice. And although your X Series camera can be easily used in this way, it will most likely not be set up straight out of the box.

What is back-button focusing?

Starting out, most photographers learn to focus by half-pressing the shutter release button. This activates the camera’s AF system, telling it to focus using the AF mode and AF area that’s been selected. Once focus is achieved, pressing the shutter release further takes the picture. This works fine a lot of the time, but there are some situations where it can slow you down, or lead the camera into focusing on the wrong part of the scene.

Back-button focusing changes this way of working for the better. Essentially, it removes the link between AF activation and the shutter button. AF is no longer engaged at the moment the shutter is pressed, and the shutter release is only used to start an exposure.

Now, you can technically set up other buttons to engage the AF system, so the one you use doesn’t need to be on the back of the camera. But this is the easiest place for it, as with the natural grip of your hand it will fall under your thumb, letting you easily manage the two buttons at once. Some cameras, like X-H2 and X-E4, are designed with dedicated AF-ON buttons in that position; others need to have a button mapped to that function.

With AF activation set to an independent button – most likely the AF-L or AE-L button if there’s no dedicated AF-ON – focus is achieved with a single tap in AF-S mode, or by a continuous press in AF-C mode. Either way, when you take your thumb off the button, focus is locked and won’t change until you press it again, even if you press the shutter release to take a picture.

Why back-button focusing is a good idea

So, with your X Series camera’s AF system being so clever, why would you want to take more control than it normally offers? There are plenty of reasons.

Back-button focusing provides the benefits of both AF-S and AF-C mode. In fact, by disconnecting the focus from the shutter release, you can work in AF-C alone and don’t need to swap AF mode settings, which speeds up your work. In that way, while we normally think of AF-S as the method of locking focus – say, for still subjects like landscapes or formal portraits – with back-button focus it can simply be done by taking your thumb off the AF-ON button, even if you’re in AF-C mode. Focusing stops, so it’s locked in position.

This is useful in situations where you might need to focus and then reframe, which is common if you don’t want to move the AF point. For instance, you can press AF-ON to focus, take your finger off the button, then recompose and shoot with the framing you want. With the normal method, as soon as you pressed the shutter button, the camera would try to reacquire focus with the AF point now in the wrong position.

Back-button focus is also very useful when switching between stationary and moving subjects. For example, say you’re shooting a bird that’s taken roost. In AF-C mode, you could lock focus on the bird using the back-button method, but as it took off, be able to activate continuous AF as normal by keeping the AF-ON button held down. By disengaging focus from the shutter button, you can also use manual focus to fine-tune or correct sharpness, without the AF being activated again when you touch the shutter release.

Keeping your finger off the shutter button has other advantages, too. It avoids pictures being taken accidentally, which can happen as you remain half-pressed to lock the focus, but apply too much pressure. It also reduces focusing errors. If having locked the focus, you accidentally take your finger off the shutter release, you’ll lose it, and will have to refocus before shooting. Conversely, a single press of the AF-ON is all that’s needed to lock focus – and the button can be held down more easily in AF-C mode.

When working in AF-C mode and shooting with a fast frame rate, there’s another advantage. Sometimes a subject, like a car or bird, will move slightly behind another object, such as a tree or spectator at the trackside. With focus set to a back button, you can just take your thumb off when that happens, keep shooting, and pick up the subject again when it’s clear. But with the focus locked to the shutter, any picture you take will initially try to focus on the obstruction.

It allows faster shooting, too, because the shutter no longer has to confirm focus, or hunt for the lock on before a picture is taken – often the difference between a unique moment being captured or missed.

Are there downsides to back-button focusing?

There’s a reason that your X Series camera is set up with focus allied to the shutter button. It’s the easiest way for beginners to understand and work. Back-button focusing involves a little more dexterity than the simpler route, as you’re using two buttons instead of one – a bit like driving a manual car as opposed to an automatic – so some coordination is needed. But it comes relatively quickly. Another downside could be that back-button focus takes away a button that you might want to assign to something else.

How to set up back-button focusing on your X Series camera

Back-button focusing is easy to set up. You just need to assign a button to the AF-ON function, then tell the camera to unlink the AF function from the Shutter button.

To do it, follow these steps:

• Hit MENU/OK and choose the SET UP menu. Then highlight BUTTON/DIAL SETTING and press MENU/OK or right on the D-Pad.
• Now scroll down to FUNCTION (Fn) SETTING and press MENU/OK or right on the D-Pad. Next scroll to the button you want to remap and press MENU/OK or right on the D-Pad
• Pick the AF-ON function from the list of options. And press MENU/OK.
• Finally, go back to the BUTTON/DIAL SETTING menu and find the SHUTTER AF option, then press MENU/OK or right on the D-Pad. Set both AF-S and AF-C options to OFF. Press the shutter button to finish.

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