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How and Why to Use Back Button Focus

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Back button focus is one of those photography terms that I had heard thrown around from time to time, but I never took the proper time to explore what it was all about. I finally sat down and did a bit of research on the topic and discovered it was something pretty awesome, so if this is something you are also curious about, read on!

Back button focus simply means you will be using a button on the back of your camera to focus instead of your shutter release. Why on earth would you ever do that? The number one reason (in my opinion) that you’d do this is when you are using servo focus mode. If you are unfamiliar with servo focus, this is a focus mode in which the camera is constantly tracking your subject as you hold the shutter button halfway down. This is a great mode to use when shooting photos of sports, your dog at the park, your kids running around, etc. Servo mode is a great feature, but can also be extremely frustrating if you are trying to focus while also trying to compose your shot. Here’s an example of what I mean: you are in servo mode, shooting your dog playing at the park. You are following your dog’s movements, with the lens constantly tracking and focusing along the way. You’d like to get a nicely composed shot of your dog, using the rule of thirds and all the other composition tricks you’ve been practicing. So as you quickly place your subject (your dog) out of dead center in the frame, with your finger still held halfway down, the camera starts trying to focus on the background instead. Because you are in servo focus mode, the camera is doing exactly what you told it to do, and the shot is ruined. At this point you might be thinking, “why would anyone use this stupid servo mode, it sucks!” This is where back button focus can really help.

With back button focus enabled, you’ll no longer be using the shutter button for focusing. Instead, you’ll be using a button on the back of the camera that’s labeled “AF-ON”. You’ll notice that this button is easily accessible by your thumb on every SLR that has this feature, and that’s on purpose. Using the above example of you trying to get a great shot of your dog playing in the park, you’d have your thumb holding the AF-ON button as you track your dog, then when you are ready to compose the shot, you’d simply take your thumb off the AF-ON button, hit the shutter release, and get a nice shot. The camera stops focusing when you let go of the AF-ON button and the shutter button is doing exactly what its name implies: releasing the shutter.

AF-ON isn’t just for servo focus mode, however. It still works great using the default “one shot” focus mode. The same technique would apply here: Use the AF-ON button to focus, release when you get the focus you want, recompose and shoot. I’ve used this technique when shooting events where there’s an important speaker talking at a podium, or someone giving a speech in which they roam the room using a hand-held microphone. It works great, and once you get used to it you might never go back!

So how do you enable this whole “back button focus” deal? It’s actually pretty easy, but you’ll need to dig into your camera’s menu settings. I’ve enabled it on a Canon 5D Mark II as well as a Canon 50D.  As soon as I learn how to enable it on a Nikon, I’ll update this post.

Here’s how to enable back button focus on a Canon 5D Mark II and a Canon 50D (the settings are identical):

  • Press the “Menu” button.
  • Scroll over to the orange camera icon.
  • Use the scroll wheel and choose C.FnIV:Operation/Others. Hit the “set” button (center button) to open the options.
  • The first option you’ll see is “Shutter button/AF-ON”. Hit SET on your scroll wheel to go into the menu options.
  • The 3rd option down is what you want. It’s labeled “2:Metering start/Meter+AF start”.

Once that’s set, you’ll use the “AF-ON” button to focus and the shutter button will only be used to release the shutter. If you want to change the settings back, go back into the menu and choose the first option (0:Metering + AF start).

Here are some images showing the settings on a 5D Mark II.

Step 1

Enabling Back Button Focus – Step 1

Step 2

Enabling Back Button Focus – Step 2

AF-ON is your new focus button!

AF-ON is your new focus button!

  • This is very clever!

    • Yeah, it’s very cool. Let’s get it working on your Nikon!

  • Val

    Yes tips for this on nikon would be great thanks

  • Amy Knott

    Thanks so much for this! Was able to figure out that I had the wrong settings enabled on my camera and I was getting so frustrated that back button focusing wasn’t working properly – and also I was not pressing the AF-ON button. Very helpful!

  • Hesvey Martin

    hi there! I’ve been using canon 7d for 4 years already and I really loved it’s double AF point back button feature. That means that you can assign a certain AF point to focus on when you press the (*) button and the other regular AF point that you can change anytime is activated when you press the AF-ON button. for example, you want to focus the upper right most AF point, just press the (*) button. and if you want to focus the upper left most AF point, just press the AF-ON button which is really a great and fast thing to do when you frequently shift from one AF point to the other that you used most of the time. is this feature also available in Canon 5D Mark II? am asking this because i bought my friend’s 5d mkii but i can’t find the feature i mentioned above. back button focusing in 5d mkii still possible but with only one settable AF point. is it possible to have 2 AF points instead?

    • Not that I know of, however the 5D2 does have a feature that’s nearly as fast, possibly faster. If you go into the C.Fn III: Autofocus/Drive Menu, then scroll to the 3rd page (AF point selection method) and choose “1: Multi-Controller direct” – the 5D2 will then allow you to use the joystick on the back of the camera (just below your thumb, conveniently) to quickly access any of the focus points. Want to use the right most focus point? Tap the joystick to the right. Want to use the top point? Tap the joystick upwards. You get the idea. It’s not exactly what you are looking for but it’s close! Let me know if you need help setting it up.

      • mark llenares

        thanks a lot Sir Tim. I really found the joystick thing very useful when I first got to test the 5D2 but it’s not what I got used with the 7D. It’s still a good thing because I will be using my 7d+70-200mm more on candid shots (i’m a part time wedding photographer anyway) which requires frequent and quick changing of AF points and I will be using my 5D2 more on beauty shots which basically do not require quick and frequent changing of AF points. appreciate your feedback Sir. thanks a lot.

        -hesvey martin

  • Martin Frick

    Hi Tim, thanks a lot for this how-to! I use this back button method already on my 6D and I love it. But one thing is strange on my 5Dii: as I have configurated the custom menu as shown here, back button focus is not set on the AF-ON button, but on the ‘star’ (lock metering) button. Do you know why? I would like to have the same configuration on both bodies…
    Cheers, Martin.

    • Hi Martin,

      I’m not entirely sure why that’s happening, but I’ll take a look at my 5D2 and let you know. It’s probably some random, weird, buried menu setting. I’ll keep you posted…

    • Caroline Gryglas

      Watch my questions to Tim, I also wrote an answer to you! 🙂

      • Martin Frick

        Hi there,
        what a great discussion, thanks very much for the helpful feedback!
        First I couldn’t solve it but finally it worked by
        1) deleting all custom preferences
        2) setting the back button focus as described above.
        So it works fine now. Thanks a lot for your help and
        good light!

  • Hi Caroline,

    I use different focus settings depending on what I’m doing, but if I was attempting to shoot something moving (like sports or your dog) then I’d definitely use AI-Servo. With the “One Shot” mode, you’ll be constantly pressing the focus button. Sorry if that was confusing in my post. I’ll update the post when I get a moment to make that a bit more clear.

    Also, thanks for the video – I figured the solution to Martin’s question must be buried in the menu somewhere!

  • sri

    Hi Tim,
    Seems like doing the custom function that you mention, will cause you to loose the AE lock feature. Any way around that ?

    • When you are using back button focus, the “AF-ON” button becomes the AE Lock. Give it a try – I just tested it on my 5D2 and it worked.

    • I just took a look – my AE lock still works unless I have the option on page 2 of the C.FnIV: Operation/Others set to “enable”. That option is “AF-ON/AE lock button switch”. If I have that Enabled, then my “AF-ON” becomes my AE Lock and the AE-Lock becomes my focus button. It’s funny, but now that I played around I sort of like this better – the AE Lock button is closer to my thumb and easier to use for focusing!

  • Thanks Tim. Just broke my Mark III and needed to go back to my Mark II while it’s in the shop. Couldn’t locate my manual but these instructions were just what I was looking for.

    • Great​! Glad I was able to help.

  • Wee Stevieb

    Hi Tim, I’m still getting used to my mkII. I’ve been taking pictures of dogs juming toward me but I’ve been prefocusing. If I take my thumb off to recompose the shot then by the time I’ve recomposed the shot the dog will be out of focus again. Can I keep my thumb on the button to keep it focussing and take the shot at the same time? I susally shoot on manual. Thanks, Steve

    • Have you tried AI servo mode for focusing?

      • Wee Stevieb

        not yet, going to try now I’ve read your article, does that mean I can press both buttons at the same time?

        • No, just hold the “focus” button down as you are tracking the subject and the camera will attempt to focus the entire time. You can fire off the shutter whenever you want to. It can be tricky to get a fast-moving subject perfectly in focus. With animals, I try focusing on the eyes.

          • Wee Stevieb

            ok, so the theory is that the camera will carry on focussing? Thanks, will give it a go.

          • Yeah, with AI Servo mode the camera will just continuously focus as long as the focus button is pressed.

          • Wee Stevieb

            Soryy, I’m confused again now. “As long as the button is pressed”, as soon as I stop pressing the focus button to fire the shutter there will be a delay in which the object could move significantly?

          • Yeah, naturally there will be a brief moment as the shot is taken that the camera is no longer focusing (the length of time of that moment would literally be whatever your shutter speed currently is), but the camera continuously focuses while in AI Servo mode – before and after you release the shutter. You might also consider using burst mode so the camera takes multiple shots in a row (that’s what most sports photographers do). The combo of AI Servo with burst mode is most likely exactly what you are looking for.

          • Wee Stevieb

            thanks, will have a play and see what happens


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