Back Button Focus: What It Is, How to Set It Up, and Whether You Still Need It

I’ve been focusing with my thumb since 2013. That was the year I bought a Canon 6D, a camera with eleven autofocus points huddled around the middle of the frame, and back button focus went from something professionals mentioned in passing to the only sensible way I could work.

Thirteen years on I’m shooting a Canon EOS R5 that can find a bird’s eye on its own, and I still focus with my thumb, although my reasons have changed more than I expected them to.

Much of the advice you’ll find about back button focus was written in the DSLR era, when autofocus points sat in the centre of the frame and cameras hunted back and forth for focus in dim light. Cameras have moved on a great deal since then. Some of the classic reasons for using this technique went away with the hardware problems that created them. Others survived. One got stronger.

Whether it’s still worth setting up in 2026 depends mostly on what you shoot, so I’ll answer that first.

 

Quick Take: Should You Use Back Button Focus in 2026?

If you photograph things that move, birds, wildlife, sport, children, pets, then yes. Back button focus is still the best way I know to run continuous autofocus, and modern subject detection has made it more useful rather than less. It’s the setup I use every single day.

If you shoot portraits or considered compositions where you focus once and then shoot several frames, also yes. Being able to lock focus and fire as many shots as you like without the camera refocusing was always the technique’s best trick, and nothing in modern autofocus has replaced it.

If you’re a casual shooter with a recent mirrorless camera and you mostly let it do its thing, you don’t need it. Eye autofocus in full auto will get you sharp photos most of the time, and there’s no prize for making your camera harder to use.

And if you’re brand new to photography, leave this one for later. Get comfortable with your camera’s basic controls first. Back button focus will still be here when you’re ready.

 

What Is Back Button Focus?

By default, the shutter button on your camera does three jobs. Half-press it and the camera focuses and meters the scene. Press it fully and it takes the picture. Focus, exposure and capture, all stacked onto one button under your index finger.

Back button focus separates those jobs. You change a couple of settings so the shutter button no longer focuses at all, and instead you focus by pressing a button on the back of the camera with your thumb, usually one labelled AF-ON. Your thumb decides when the camera focuses. Your finger decides when it takes the picture.

It doesn’t need special hardware. Most interchangeable lens cameras from the past decade can do this, even entry-level models without a dedicated AF-ON button, because you can normally assign the focus job to another rear button (the exposure lock button is a common choice). It’s just a settings change, and it’s completely reversible.

 

Do You Still Need Back Button Focus on a Modern Camera?

The classic case for back button focus was built on how DSLR autofocus worked, and autofocus has changed almost beyond recognition since those arguments were first made. So the fair way to answer this is to go through the old reasons one at a time. Some of them didn’t survive the move to mirrorless.

 

The Reasons That Went Away

The big one is focus and recompose. On my 6D, the eleven autofocus points sat in a small diamond around the centre of the frame, and the centre point was the only one I trusted in difficult light.

So the standard technique was to focus using the centre point, hold that focus, and swing the camera to the composition you wanted. Back button focus made this fluid: focus with the thumb, recompose, shoot. For a whole generation of DSLR shooters, me included, that’s why the technique became second nature.

Mirrorless cameras mostly ended that. My R5 has 1,053 autofocus zones the camera can choose from, covering roughly the whole frame (Canon quotes approximately 100% coverage, with the caveat that it varies by lens and settings).

Those are automatic selection zones rather than the individually selectable points of the DSLR era, so the two numbers aren’t a like-for-like comparison, but the practical difference is easy to state: on a modern mirrorless body you can put focus almost anywhere in the frame without moving the camera. If focus and recompose was your main reason for using back button focus, your camera has probably retired it.

The 100% figure is a flagship number, mind. Canon’s cheapest mirrorless body, the R100, covers about 88% of the frame horizontally. That’s still a different world from eleven points in a diamond.

Low-light focus hunting mostly went the same way. My 6D was rated to focus down to -3 EV, and only on the centre point, with the other ten points a fair bit less capable. The R5 is rated to -6 EV.

I’d love to tell you that’s a clean three-stop improvement, but the two figures were measured under different conditions (Canon assumed an f/1.2 lens for the R5 number and didn’t for the 6D’s), so treat spec-sheet comparisons between eras with suspicion.

What I can tell you from owning both cameras is that the R5 locks on in evening light that would have had the 6D sawing back and forth, and that keeping focus held to avoid a re-hunt, one of the old arguments for back button focus, just isn’t the daily problem it used to be.

If you’re still learning your way around a mirrorless body, my guide to using a mirrorless camera covers all of this from the beginning.

 

The Reasons That Survived

Locking focus between frames is the strongest survivor. Focus on your subject, let go of the button, and the camera holds that focus for as long as you like, however many frames you take.

If you shoot portraits you’ll know the annoyance this removes: you focus on an eye, adjust your framing, and the camera cheerfully refocuses on the wall behind them the moment you press the shutter again. With back button focus, that class of accident is gone. The camera only refocuses when you tell it to.

Separating focus from the shutter also survived intact. If you like to set focus on a fixed spot and wait for something to arrive there, a perch, a doorway, a finish line, back button focus is still the cleanest way to do it. Focus once, then shoot whenever the moment happens, with no risk of the camera second-guessing you at the worst time.

And the same separation is what saves you when you can’t afford a re-focus: once you’ve got the shot ready, no half-press fumble can undo it.

 

The Reason That Got Stronger

Subject detection and back button focus turn out to be a very happy pairing. My R5 will find and track an animal’s eye entirely by itself. What it can’t know is when I want it tracking. With autofocus on the back button, that decision stays under my thumb: hold AF-ON and the camera tracks, take my thumb off and it stops focusing altogether, leaving focus exactly where it was. The shutter button never interferes with any of it.

One reality check before you rely on this, though. Human eye detection is close to universal on current mirrorless cameras, but animal detection isn’t. Canon’s entry-level R100 detects people only, with animal detection starting at the R50 tier, while Nikon’s Z30, Sony’s ZV-E10 II and Fujifilm’s X-T30 III all include it.

It’s generation-sensitive too: Fujifilm’s X-T30 II lacks the newer subject detection its successor has. If your camera is a couple of years old, check what it actually offers rather than assuming.

 

How I Use Back Button Focus on My Canon R5

To make this concrete, here’s my actual setup. I described it recently to a reader who’d moved from a 5D to an R5 and found that focusing felt different. It does, and it took me a while to settle on this arrangement too.

The camera is set to full autofocus with subject detection on, switched between people and animals depending on what I’m photographing. Most of the time that means animals, since this camera, with my EF 100-400mm f/4.5-5.6L IS II on an adapter, is what I shoot birds with.

I hold AF-ON with my thumb the whole time I’m tracking a subject, and I press the shutter with my finger to take pictures while the thumb stays down. I don’t release the button to lock focus as a habit, because releasing it stops the camera focusing, and with a moving subject that’s rarely what I want. Hold, track, shoot.

Then there are my two escape routes for when the camera guesses wrong, locking onto a branch in front of a bird, say. The first is the M.Fn button next to the shutter, which I use to switch focus modes quickly. I also use it for ISO, since the R5 annoyingly lacks a dedicated ISO button: press M.Fn, scroll to the setting you want with the rear wheel, change it with the top dial.

The second is the button on the front of the camera, at the bottom right of the lens mount as you’re holding it, which by default is the depth of field preview button. I’ve reassigned it to autofocus with a single centre point (the setting lives under C.Fn3, Customize buttons, then the DOF preview button, ticking AF method).

Holding that button together with AF-ON gives me old-fashioned centre-point focus, exactly how I worked on the 6D. Once focus lands where I want it, I let go of everything and take the shot.

Now for the part that surprised me. I built this setup so I could keep working the way thirteen years of muscle memory expected, and the R5’s autofocus is clever enough that I rarely use the overrides at all. The subject detection really is right far more often than it’s wrong.

So it’s good to know how to take back control, but on this camera the override is a safety net rather than the technique itself. On the 6D, it basically was the technique.

Current cameras let you customise almost everything, so start with the arrangement above, thumb on AF-ON to track, front button for the override, and adjust from there. The test is speed: the setup that lets you react fastest when a subject appears is the one to keep, even if it’s not mine.

 

And on a DSLR: My Canon 6D Setup

None of the mirrorless talk above means DSLR shooters are left out. I still own two 6Ds (they still take a lovely photo), and back button focus arguably matters more on a DSLR, because you’re working with the exact constraints that created the technique.

On the 6D I keep the centre point selected, it’s the most accurate of the eleven, particularly in low light, then focus with AF-ON, recompose, and shoot. That was my default for years, and it still works just as well today as it did in 2013.

If you’re getting to grips with a DSLR more generally, my DSLR beginner’s guide covers the wider skills.

 

How to Set Up Back Button Focus on Any Camera Brand

Whatever the brand, the recipe is the same two steps. Miss either one and it won’t feel right:

1. Stop the shutter button from focusing on half-press.
2. Assign autofocus to a back button (AF-ON, where your camera has one).

Exact menu names drift between models and generations, which is why this table stays at menu-family level rather than quoting screen numbers for specific bodies. It will get you to the right menu; your manual or the linked official guide covers your exact model.

Brand	Step 1: take focus off the shutter	Step 2: put focus on a back button	Official reference
Canon	Custom Functions (C.Fn) menu, Customize buttons: set the shutter half-press to “Metering start” (the default is “Metering and AF start”)	The AF-ON button focuses out of the box on most models; you can adjust it in the same Customize buttons screen	Canon online camera manuals
Nikon	Custom Settings, the a (Autofocus) menu: set AF activation to AF-ON only, which stops half-press focusing in one move	The AF-ON button is ready to go on most Z bodies; on smaller models, assign AF-ON to a rear Fn button	Nikon Z online manual
Sony	In the focus settings (MENU, Focus, AF/MF), set AF w/ Shutter to Off (“Select [Off] to adjust the focus and the exposure separately”, as Sony’s own guide puts it)	Focus with the AF-ON button, or assign the function to AEL on older bodies	Sony Help Guide (a7 IV)
Fujifilm	SET UP, then BUTTON/DIAL SETTING: switch SHUTTER AF off	In BUTTON/DIAL SETTING, FUNCTION (Fn) SETTING: set the AF-L button to AF-ON. Fujifilm has a real AF-ON function, it just lives on the button labelled AF-L	Fujifilm’s back button focus guide
Panasonic	Custom menu, Focus/Shutter: set Shutter AF to Off (it ships set to On)	AF-ON is an assignable function, and many bodies have a dedicated button for it	Panasonic S5 II manual

A note on that first step, because it’s the one people skip: if the shutter still focuses on half-press, you don’t have back button focus, you have two focus buttons fighting each other. Do both steps.

 

What Happens to Metering and Exposure?

This is the question I’m asked most about back button focus, and it confused at least one reader of the earlier version of this article, which was my fault for explaining it badly. The worry goes: if the shutter button handles exposure, do I have to half-press it to meter before every shot? Wouldn’t that defeat the point for fast-moving subjects?

The reassuring answer is no. On most cameras the metering system runs continuously while the camera is active, so by the time you press the shutter all the way down, the exposure is already sorted. There’s no separate half-press step required. For fast subjects, focus with your thumb and press the shutter when the moment comes; the camera sets the exposure as it fires.

The half-press still exists, of course, and on many cameras (depending on your settings) it locks the exposure reading, which is handy when you want to meter from one part of the scene and hold that value while you recompose.

Sony owners get an extra choice here, and it’s one to set deliberately. The setting is called AEL w/ Shutter and it has three positions: On locks the exposure on every half-press, Off never locks it, and Auto locks it only once the half-press has adjusted focus. If you want the lock, pick On, since it works on the half-press whatever focus is doing.

If you already use that technique deliberately, it keeps working. If you’ve never heard of it, you can safely ignore it. And if you’d like to understand what the meter is actually deciding, my guide to the exposure triangle is the place to go.

 

How to Use Back Button Focus

Once it’s set up, the technique itself is pretty quick to learn. Your hands take a bit longer.

For static subjects: put your focus point on the subject (or let subject detection find it), press AF-ON until focus confirms, then let go. Focus now stays where you set it. Compose, take the shot, take five more, and the camera won’t refocus between any of them. You only need to press AF-ON again if you or your subject moves, or you change focal length.

I usually recompose after focusing rather than shooting with the subject dead centre, and if you want to get better at that side of things, my guide to composing great photos goes into detail.

For moving subjects: switch to continuous autofocus (Servo AF on Canon mirrorless, AI Servo in Canon DSLR terms, AF-C on most other brands), hold AF-ON down, and keep your subject under the focus point, or let tracking follow it for you. Shoot with your finger whenever you like. Your thumb doesn’t leave the button until the action ends.

This is where back button focus makes safari photography and bird photography feel dramatically easier: one digit worries about sharpness, the other about timing.

And when the camera grabs the wrong thing, a blade of grass in front of an animal, a branch in front of a bird, having focus under your thumb is what gets you out of it. Stop focusing, override (with a single-point button like my front-button setup, or by moving your point), and reacquire.

I know this failure well, because I have a frame where the camera chose some blades of grass over an entire rhino. The pair below shows exactly what I mean.

 

 

Reasons Not to Use Back Button Focus

It would be easy to pretend there are no downsides. There are three.

The first is other people. In our experience the biggest drawback comes when you’re out and about and ask a stranger to take your picture (one of our techniques for getting photos of yourselves as a couple). Trying to explain back button focus on the fly to a photography novice is generally not something you want to be doing!

My solution is that I know how to disable it quickly on my camera, and I do that before handing it over.

Another option we’ve used is to set up the shot beforehand and ask the person to press only the shutter button. If you set a fairly high aperture (around f/8 to f/11), most lenses will be forgiving of focus thanks to depth of field, so even if they move a bit, the shot will come out fine. Otherwise, get used to carrying a travel tripod and taking photos of yourself that way. It will likely turn out better anyway!

The same problem appears in reverse when you pick up a camera that isn’t yours, a rental or a friend’s body: your thumb goes hunting for a button that isn’t doing anything.

The second is the changeover week. Your hands have years of practice at half-pressing to focus, and for the first while you’ll raise the camera, half-press, and wonder why nothing is happening. You’ll miss a shot or two while your brain rewires. Everyone does. The cost is real but short-lived, which is why I’d make the switch before a quiet week at home rather than the day before a safari.

The third is timing. If you have a brand new camera and you’re just starting out in photography, I’d suggest leaving back button focus until you’re comfortable with how everything else works. It’s a technique I’d hate to give up, but it isn’t compulsory, and plenty of working photographers do without it. Try it when you’re ready, give it a fair week, and keep it only if the control feels worth it to you.

 

Back Button Focus: Your Questions Answered

These are the questions I’m asked most often about back button focus, here in the comments and by students on my photography course. If yours isn’t covered, ask in the comments and I’ll do my best, and my guide to common camera problems answers plenty more.

 

What is back button focus in photography?

Back button focus is a camera setup where autofocus is moved from the shutter button to a button on the back of the camera, usually AF-ON. Your thumb controls focusing and your index finger only takes the picture, so the two jobs never interfere with each other.

It’s a settings change rather than a special feature, and it’s fully reversible if you decide it isn’t for you.

 

Is back button focus still necessary on mirrorless cameras?

It was never strictly necessary, and on a modern mirrorless camera some of the old reasons for it (focus and recompose, low-light focus hunting) largely no longer apply. What remains is control: locking focus between frames, and deciding exactly when the camera tracks a subject and when it stops.

For action, wildlife and portrait work I’d still set it up on any camera I own. For casual shooting with eye autofocus doing the work, you can skip it with a clear conscience.

 

Is back button focus better than half-pressing the shutter?

For photographers who want control over exactly when the camera focuses, yes, it’s a better system: focus and shutter stop sharing a button, so one can’t spoil the other. For photographers who just want sharp photos with minimum fuss, half-press focusing on a current camera works very well.

It’s a preference, not a rule. I’ve used back button focus since 2013 and wouldn’t go back, but the technique should serve you, and if it doesn’t, don’t force it.

 

Do you hold the back button down all the time?

For moving subjects, yes. I hold AF-ON continuously while the camera tracks, and press the shutter to take pictures while my thumb stays down. Releasing the button stops the camera focusing, which isn’t what you want mid-action.

For static subjects, no. Press until focus confirms, let go, and the focus stays put for as many frames as you like.

 

How does metering and exposure work with back button focus?

Your camera meters continuously while it’s active, so you don’t need to half-press the shutter before each shot. Press the shutter fully and the exposure is set as the picture is taken.

On many cameras a half-press will lock the exposure reading, which is useful if you deliberately meter from one part of the scene, but it’s optional, not a required step.

 

Does back button focus work with eye autofocus and subject detection?

Yes, and the combination is excellent. Subject detection decides where focus goes; the back button decides when. Hold AF-ON and the camera tracks the eye, release it and tracking stops with focus held in place.

Check what your specific camera detects, though. Human eye detection is nearly universal on current mirrorless bodies, but animal detection isn’t, Canon’s entry-level R100 detects people only, for example.

 

What’s the difference between back button focus and back focus?

They sound alike but are unrelated. Back button focus is the control setup described in this article. Back focusing is a fault, where the camera or lens consistently focuses slightly behind the subject you aimed at.

If your sharp point keeps landing behind your subject, that’s a calibration problem (more common on DSLRs), and no button assignment will fix it. Some cameras offer autofocus micro-adjustment for exactly this.

 

Is back button focus good for beginners?

I’d wait. When you’re new, the priority is understanding exposure, focus modes and your camera’s controls, and moving autofocus to a different button adds friction without teaching you anything.

Once the basics feel automatic and you know what you shoot most, come back to it. The changeover takes a week or so of awkwardness, and it’s much easier when the rest of the camera already feels familiar.

 

Do all cameras have back button focus?

Most interchangeable lens cameras made in the last decade support it, either with a dedicated AF-ON button or by assigning focus to another rear button. Compact cameras often don’t. My Sony RX100 V, for example, is a camera I use with regular shutter-button focus.

The quick test: look in your camera’s custom button or custom function menus for an AF-ON function, and for a setting that stops the shutter half-press from focusing. If both exist, you’re in business.

 

Can I still use focus and recompose with back button focus?

Yes, they work together nicely: focus with your thumb, release, recompose, shoot. That combination is exactly how I shot for years on my Canon 6D, using the centre focus point.

On a modern mirrorless camera you’ll need it less, since focus points cover nearly the whole frame, but it remains a fast, reliable habit. One caution: at very wide apertures and close distances, swinging the camera after focusing can shift the plane of focus slightly, so for critical work, put a focus point on the subject instead.

 

Further Reading on Photography

Focusing is one skill among several, and these guides carry on from here:

• My guide to aperture priority mode, which pairs naturally with back button focus for travel photography
• Everything I know about safari photography, where this technique gets its hardest workout
• Choosing the best travel camera, if you’re shopping for a body that supports everything in this article
• My guide to the best travel camera lenses to go with it
• Jess’s beginners’ guide to improving your travel photos, which I contributed to over on Independent Travel Cats
• The full archive of my photography tips, which I’m always adding to

 

Looking to Improve Your Photography?

If you found this post helpful and want to take your photography further, check out my online travel photography course. Since launching it in 2016, I’ve helped over 2,500 students learn how to take better photos, covering everything from how a camera works through to composition, light and photo editing, with feedback from me as you progress.

It’s a one-off price for lifetime access, and you can read all about it here.

 

And that’s it! As always, if you’ve got any questions about back button focus, or photography in general, do pop them in the comments below and I’ll get back to you as soon as I can.