Back-button Autofocus Is Even Better on Mirrorless Cameras, and Here’s Why

As a photography instructor, one of the most common questions I see from students is about back-button focus. It's easy to gloss over it to keep things simple for new users, but doing so on the latest generation of mirrorless cameras leaves a lot of useful features on the table. It's worth learning.

I've seen a lot of explanations over the years, but Canadian wildlife photographer Simon d'Entremont has offered up the best explanation of this often overlooked feature of most mid-range cameras and up (and, hallelujah, even the entry level Canon Rebel T8i finally got a dedicated AF-On button, so no more using the auto-exposure lock (*) key to assign to what I consider a critical camera function).

I discovered the importance of back-button focus years ago when using the focus and recompose technique, mostly because the cameras I was using (the original Canon EOS 5D, then the 5D Mark II, and later the 6D) had lousy outer focus points, and so, I would hit the focus with the center cross-type autofocus point, then recompose by moving the camera slightly. This made it nigh-impossible to work with very shallow depth of field, because at something like f/1.4, you'd still slightly lose focus this way, but it was better than the camera missing focus entirely with every shutter button press. With the original 5D, I had to reassign the AEL button for this purpose, but Canon wisely added a dedicated AF-On button to later models. I also found it useful for more precisely controlling my focus for sports photography.

In fact, about the only time I ever turn off this function is when I'm shooting around friends and family and I know that I want to be in a photo. No one ever understands the concept of back-button focus, and so, it's easier to have one button do both focus and capture at once for the uninitiated.

All that said, even if you are a long-time user of back-button autofocus, you'll want to check out this video. As a long-time DSLR user, where eye-detection autofocus wasn't even a thing, when I purchased my Canon EOS R6 (and this applies to R5 users as well), I immediately set it up with back-button autofocus just like my 10-year-old 6D. These newer cameras have face- and eye-detection autofocus; however, I found it difficult to jump between these modes and traditional autofocus modes where I had more control over the area. I found myself using my shiny new camera much of the time without its advanced eye-tracking feature because it was too cumbersome to dive into the menu. d'Entremont shows you a way to configure your back-button autofocus to sidestep around this problem so that you can have your cake and eat it too, as in get that back-button focus you are used to while also quickly being able to access eye-detection features. I know my mind was blown when I saw this, so even if you've been shooting professionally forever, it's worth getting to the end of the video to check out d'Entremont's setup. He goes through setups for newer mirrorless models as well as older DSLRs.

Are you a fan of back-button autofocus? What do you use it for? Share your own tips and tricks in the comments below.

Wasim Ahmad's picture

Wasim Ahmad is an assistant teaching professor teaching journalism at Quinnipiac University. He's worked at newspapers in Minnesota, Florida and upstate New York, and has previously taught multimedia journalism at Stony Brook University and Syracuse University. He's also worked as a technical specialist at Canon USA for Still/Cinema EOS cameras.

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I tried back button focus but because of my muscle memory I kept forgetting about it and instinctively went for the shutter button! I finally gave up on it. Old habits are hard to break at my age!

I too had the same issue when I tried it years ago on my DSLR. I just kept messing up. But I made a commitment to myself to give it a month on my 6 mo. old R5 now that I got most of the setting figured out. I didn't have any work planned so it was a good time to try a new thing. My goal was to shoot every day and with different subjects. Including things that were fast-moving. I even shot photos while riding on the top deck of a bus racing down the freeway. It kind of forced me to work harder. I discovered my hit rate increased.

I mostly was using spot focus and recompose similar to how I shot film back in the day. I've now moved on to using not only two BBAF, but I've also now programmed my camera to have three BBAF. Yes! Crazy I know. But I have the main AF-On set to Spot AF. The second is on Eye Detect AF, and the third on general objects. This is my daily setup. To really challenge myself I have C2 programmed for weddings so Eye Detect AF is on the main button (AF-On). The second is Spot AF, and the third is ISO. I just put it in my mind I'm shooting three different cameras, C1 (daily),C2 (weddings),C3 (birding).

It's been about 6 months now, and I don't even think about it. It's all muscle memory now. So happy I was able to retrain my brain to do this because now I have so much more control of my focus points. It brings me back to the days of manually focusing my camera first then checking and/or changing settings, then pressing the trigger. I'm so old school I even use my lens control ring to adjust my Aperture.

I hope you give it a try again as I did. It's really a good skill to learn.

Recomposing was always one of my peeves without back button AF (BBAF). But, I also do timelapse work as well. Once I remove AF from the shutter button, the camera is freed from having to refocus on each shot however slightly. That's less work for the camera to do and less chance of errors. Also, I set up my camera for BBAF with AF-On for "regular" focusing with servo and the (*) button activates face-eye detection. It saves me a lot of time.

Back button focus and switching to manual totally elevated my work in the past year

Sorry but I think if you are using back focus on cameras like the R5 and R6 you don't know the cameras well enough. Using your thumb on the LCD screen to focus is the best new camera feature since diced bread or the invention of autofocus. This combined with eye detection make the back button superfluous.

You can touch the screen while you're using the viewfinder? Crazy!

My screen shuts off on my Z6ii when I use the viewfinder.

Diced bread = tiny sandwiches

I used the LCD screen many times to rack focus but had issues with my nose messing me up. I shoot with my left eye so my nose gets in the way no matter where I put the focusing partition on the LCD. I just use the BBAF and let the camera find the eye or face. I use a second BBAF to Spot focus. Really happy that's I've re-trained my muscle memory to make the switch. When shooting at night though, I turn on the LCD backscreen to touch-AF and I really love that feature when I'm shooting stars or the moon. 😊

I really tried to love the touchscreen autofocus stuff over several generations of Panasonics and Canons, but it never feels natural or comfortable to me.

I mostly shoot action so they back button focus just complicates capturing the moment. For landscape or portrait I could see where it would be useful.

Funny, I've come to the opposite conclusion--BBF is less useful on mirrorless cameras. My MILC can use nearly the entire sensor for focusing, and by using a fixed starting point and continuous AF, all I have to do is place it on my subject, half press the shutter, and frame the shot however I want whether or not the subject is moving.

I've tried it a few times over the years, but, always ended up going back to normally shutter af. Back button af to me just takes an extra unnecessary step. Normal button is just quicker. No muss, no fuss.

From time to time, I may have a need to pre-focus on something and recompose, but, that's what the custom buttons on the body; or af/mf switch on the lenses are for.

Interesting concept with two separate buttons - one set up for center focus, the other for face detection and quickly switch between both by separate buttons. Would like to try this on my Sony A7RII and watched out for instructions to be given in the video. But other than a list of cameras there was nothing in the video. I have already set up my camera with one back button focus and center focus point. Just don’t get it how to set up another button for face detection back button focus.

He shows this for Canon in the video, but unfortunately not Sony. Not sure how that would work on that brand as I'm not a regular Sony shooter.

I photographed School Sports. Back Button Focusing took a short time to get use to but then I wondered how I ever got along without it.

I have been using bbf as far back as my Nikon D600 for wildlife photography. Even my Nikon v series bodies had that capability. Usually combined to AF-C & one of the area modes or single point. Auto-ISO is also a big help when shooting in M mode, wide open and appropriate ss for wildlife action.

Been using BB for years but only with center point autofocus. If I’m letting the camera decide what and where to focus on then BB doesn’t help as much.

The downside, as you say, is handing it off to friends. On the golf course people often pick up the camera when it’s my turn to hit my shot like “let me take a few of you,” and I just end up with a bunch of blurry photos of my swings.

Back button focus is the greatest invention, a sure way to miss once in a lifetime shots. If preforming button and joystick maneuvers before pressing the shutter button to capture images isn’t nuts especially with eye auto focus.

it's even more useful if..

you set it to use AFC,which is defacto AFS when you take your thumb off

You program another button for exposure lock

you program another button to flip between single point and matrix exposure

Yes that feels like a handful at first,but this way you can efficiently take on most things without moving your eye from viewfinder

I've tried BBF and don't like it. To me, the two key things are:
1. Quick reaction to plays.
2. Low frequency of focus-recompose-release.

My set-up:
1. Shutter button unchanged (focus & release).
2. AF-ON button: unchanged.
3. Depth-of-field(DOF) button: change to disable autofocus.

1. Quick reaction:
For me, reacting to a quick play (eg, liner to third base, rebound to guard, QB pass to receiver) is most often quicker by by just pressing the shutter button. Then, final focus and exposure happen at machine speed. If prefocus helps then I can push AF-ON, the same as BBF. OTOH, with BBF, two digits are needed: thumb to push AF-ON, followed by finger to push shutter. Pushing with thumb followed by finger is slower than pushing just the finger and letting the (speedier) camera do focus followed by release.

But, what about focus-recompose-release?
2. I do this rarely, and never during action shots (no time). So, slower pressing of DOF-preview (vs just releasing AF-ON) is justified given the faster reaction to action (#1).

🙂 I've been using Dual (sometimes Tripple) BBAF for over 6 months and I can't shoot without it. My hit rate has increased significantly because of this method. I'm also able to turn on AF when I want it on. The Canon R5's autofocus is fantastic but it's not perfect.🤨 The R5 finds focus where I want it only to switch to another subject just as I continue to press the shutter. With BBAF you can allow the camera to find focus and then release the button when it's done. Or just hold the BBAF down then press the shutter. Which is best for high action like sports ⚽️ or hyper children. 😂

You might say just use the shutter/AF default for sports action. Well, there is an issue with that. There are times when I want to get a hockey stick on the puck in perfect focus but the camera still wants to get the player's eyes 👀 in focus. Not what I want! With Dual BBAF, I can program one button for the eyes of the player and the other for objects (spot) like an American football 🏈 with a hand ✋🏻 on it as the player is crouched down. This is super important if you are shooting wider Apertures and want to blur the background for that mega cool shot.

The joystick is too slow. I only use that for objects while on a tripod or just used the back screen. As for back screen AF, my nose (I'm left-eyed) touches the screen and messes it up (although I still use it for shooting the moon, stars, or landscapes).

I come from a background of manually focusing film cameras (SLR) 📸. I would focus, shoot or focus and recompose. I got so good, that could shoot fast-moving cars at a NASCAR 🏎 speedways right against the fences. Meaning I could rack focus as the car was approaching me. So this method of pressing the BBAF and recomposing was very natural for me and much faster than I could turn the focus ring. But I had to retrain my brain as I've been shooting single-button Shutter/AF for so long that it was very trying for me. It took me a month to get it down. Now in my six months, It's second nature. In fact, since I shoot Dual BBAF that has come second nature.

I've even advanced to using 3 buttons to switch between the different types of AF. For general photography, I have AF-On set to Spot AF. The star button is set to Eye Detect AF and the 3rd button is set to full-screen subject-tracking AF. I've even programmed C2 for weddings where Eye Detect AF is on the AF-On and Spot AF is on the Second. The 3rd is set for ISO combined with a dial as I use Fv mode which gives me the option to put everything on full auto and go manual for any setting quickly. I have C3 set for birds.

The thing is Eye detection is good for one or two people when they are close. But get a crowd and you need Spot AF. I'll just spot on one person then another and so on. Or just close down and shoot at f/7.1 or thereabouts. I've also noticed that I can just leave Continous Focus on and it's only active when I press the BBAF. That not only saves the battery, it also reduces wear on the lens. I've also found sometimes I get the red flashing box telling me It can't focus, so pressing one of the other two buttons gets it working again. Something I've never been able to do with shutter focus.

The only thing I can think of that would get me to stop using BBAF is the photographer's eye-tracking as in the Canon R3. It focuses on whatever I'm looking at. So the player's eyes or the ball, the camera would adjust for that. I think with that you could go back to single button shutter/AF if the camera was spot on with your eye tracking. The R3 is a sports photography camera. I don't shoot sports primarily so the R5 is great for weddings, portraits, and product photography. We'll wait and see what the R1 can do. I think it will have all the features of the R3 but with a 100+ MP sensor. I would buy that and maybe drop using the Dual BBAF if the eye-tracking works out. 😊