Back-Button Autofocus is a technique you should learn

Are you a 'back button' autofocus shooter? Here's why you should be. (Copyright 2009 / Andrew Boyd)

Are you a ‘back button’ autofocus shooter? Here’s why you should be. (Copyright 2009 / Andrew Boyd)

BACK-BUTTON AUTOFOCUS, THE RATIONALE

[Editor's Note:  This post explaining back-button autofocus has been one of the most popular ever written here on The Discerning Photographer. It's accounted for thousands of page views over the past few years as people look for information on this incredibly powerful and easy-to-use technique. I remember when I first started using back-button autofocus and how difficult it was the first couple of weeks. But after that, I would never go without back-button autofocus--it's just that superior. Here's the entire post for you to consider. Read through it once straight through, then read through it again slower, maybe while having your camera in hand.--/DiscerningPhotog]

Does your camera have back-button autofocus? Is it an option on your DSLR to switch between shutter-driven autofocus and thumb-driven back button? If you grew up on shutter-driven autofocus and never bothered to relearn, you’re selling yourself short. Here’s why….

I remember when Canon first came out with the back-button autofocus option, early in their roll-out of their clearly-superior autofocus film cameras. It was 1989, and I was a Nikon shooter at the time. Nikon went through all sorts of contortions to try and explain away Canon’s innovation…which Canon had a patent on. It took Nikon several years to figure out a way to make their own back-button autofocus option without violating that Canon patent, but in the meantime, we Nikon shooters watched our Canon counterparts with envy.

Why? Well, as a newspaper photographer who has shot a whole lot of action-driven events (sports and news, mostly), you come to quickly see the genius of the back-button autofocus approach: it separates the focus function from the exposure function! This is critical! Let’s say you’re shooting a hockey fight. You autofocus with your thumb while shooting away with your index finger….now other players skate into view between you and the fight….you remove your thumb from the focus button, in effect locking the focus on the fight, while you continue to shoot with your index finger. Separating these two distinct functions allows you to have much greater control over your focus/exposure relationship!

Contrast this with the same situation but with focus and exposure both tied into the shutter release button. Shooting the same fight, you’ll have far more trouble keeping what you want to focus on in focus…things will be jumping around…you’ll be missing photos!

Separating the two functions — focus and exposure– has clear advantages. (Copyright 2009 / Andrew Boyd)

It also comes in handy every time you want to focus on something on one side of your frame, then recompose without refocusing and shoot the photo. This happens a lot with wide angle compositions. Instead of having to switch your focus point over t0 the left or right side of the viewfinder, with back button, you simply focus on the point you want in focus, then recompose and shoot your frame.

So do yourself a favor. If your camera has the back-button autofocus option, learn to use it! You probably will need to dig around in the Custom Settings for your camera to figure out how to set this up, but it will be worth it. At first this will feel incredibly awkward—you’ll be uncomfortable as you start making the change. (Sort of like rubbing your stomach and patting your head—I never was much good at that!) But keep at it. Soon back-button autofocus will become second nature and you’ll find your percentage of in-focus photographs going up!

Quick Tip: Learn to Use Back-Button Autofocus

Does your camera have back-button autofocus? Is it an option on your DSLR to switch between shutter-driven autofocus and thumb-driven back button? If you grew up on shutter-driven autofocus and never bothered to relearn, you’re selling yourself short. Here’s why….

I remember when Canon first came out with the back-button option, early in their roll-out of their clearly-superior autofocus film cameras. It was 1989, and I was a Nikon shooter at the time. Nikon went through all sorts of contortions to try and explain away Canon’s innovation…which Canon had a patent on. It took Nikon several years to figure out a way to make their own back-button option without violating that Canon patent, but in the meantime, we Nikon shooters watched our Canon counterparts with envy.

Why? Well, as a newspaper photographer who has shot a whole lot of action-driven events (sports and news, mostly), you come to quickly see the genius of the back-button approach: it separates the focus function from the exposure function!This is critical! Let’s say you’re shooting a hockey fight. You autofocus with your thumb while shooting away with your index finger….now other players skate into view between you and the fight….you remove your thumb from the focus button, in effect locking the focus on the fight, while you continue to shoot with your index finger. Separating these two distinct functions allows you to have much greater control over your focus/exposure relationship!

Contrast this with the same situation but with focus and exposure both tied into the shutter release button. Shooting the same fight, you’ll have far more trouble keeping what you want to focus on in focus…things will be jumping around…you’ll be missing photos!

It also comes in handy every time you want to focus on something on one side of your frame, then recompose without refocusing and shoot the photo. This happens a lot with wide angle compositions. Instead of having to switch your focus point over t0 the left or right side of the viewfinder, with back button, you simply focus on the point you want in focus, then recompose and shoot your frame.

So do yourself a favor. If your camera has the back-button option, learn to use it! At first this will feel incredibly awkward—you’ll be uncomfortable as you start making the change. (Sort of like rubbing your stomach and patting your head—I never was much good at that!) But keep at it. Soon back-button will become second nature and you’ll find your percentage of in-focus photographs going up!

Hi, I’m Andrew Boyd, a.k.a. The Discerning Photographer, and I hope this post has been interesting and informative. Please leave me a comment about it, let me know what you’d like to see more of on the site! You can also sign up for email delivery of all future articles or my RSS feed. Or subscribe to our Facebook page ,Google+ pageor our Twitter feed. Thanks!–DiscerningPhotog

Posted in: How To

About the Author:

Photographer, videographer and photo editor. Host and creator of The Discerning Photographer web site. Currently a Canon shooter.

28 Comments on "Back-Button Autofocus is a technique you should learn"

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  1. Ted says:

    That’s actually really true. When I found out about this on my Canon (I have a 450D so they even include it in the low end models) I was really excited. This article has reminded me to try and use the feature more often. The hockey fight is a really vivid example. I’m thinking of the shot still being correctly exposed at the heat of the action, but with the blur of a closer figure cutting in at the edge of the shot, which would create a great image!

    Thanks for the reminder.

  2. Thanks Ted. You’ll find that once you teach yourself to use the back button, you’ll never want to go back….too many situations will arise where it will give you superior results. Good luck!

  3. Been rolling with this method for a while now. It takes half an hour to get used to.

  4. Hey Kirstin,
    Way to stick with it. That shot of the couple up under the umbrella will end up being their long-term favorite. But you really might want to pick up a couple of rain covers from Fotosharp–they can cover the on-camera strobe too!
    Cheers!

  5. calliezant says:

    Everywhere I turn I hear about bbf! I am going now to change the settings on my camera and give this a try! Today is the day!

  6. Excellent! You won’t be sorry, just give yourself time to really learn it.

  7. Patti says:

    I’m a convert…my play cam has no BBF. I find myself confused, like a caveman photog……lol.

  8. Cara says:

    Hi!

    Is there a way to test if it is working properly? This may sound strange and it may be that I’m doing something wrong, but I can’t seem to see a difference from when I’m holding the back button to when I’m not. The autofocus still REfocuses when something moves in front of the subject I’m trying to keep in focus. And the idea is for that NOT to happen, right? (ie locking the focus on the hockey players fighting and not the other players passing in between you and the fight?

  9. Cara says:

    I figured it out! It has to be activated/enabled in Custom Functions (#9 on the Rebel XS)

  10. You’ve got to LET UP with your back-button thumb when you want the autofocus to lock–that’s what gives you the control. You can continue to shoot away but by learning to use your thumb for focus, you can decide when the focusing is happening…that’s what makes it work.

  11. I am playing with my camera too. I just got a new Canon E500, so I will surely give it a try.

  12. Aristarkhos says:

    I read about this on the Canon website a while ago. It is very useful to separate the two functions and while i do understand some of the explanations I am still not clear about the center focus-shift composition-shutter release method. Maybe this is because I have never really tried this recomposition method before.

    I don’t think you could have explained it simpler but I just can’t seem to picture it in my head…when I go off center after focusing on the center spot, do i focus again on the subject, which is now on the side or am i still focusing on the center spot, which is now the background.

  13. No, you don’t have to refocus. The point of the back button is with the focus and shutter separated, your first focus point will hold when you recompose and shoot the photo.

  14. Melissa says:

    For sports photographers and others taking action pictures, back-button AF lets you stop focus whenever something might interfere with the moving subject you’re tracking — without requiring you to stop shooting. In sports, for instance, it’s common for a referee or another player to come between the camera and an athlete being photographed. With back-button AF, it’s easy to momentarily pull your thumb off the rear button, and you can still keep shooting by pressing the shutter button fully. The camera instantly stops focusing when your thumb comes off the back button. Once the obstruction is out of your way, you can immediately pick-up your primary subject by pressing your thumb on the back button again.

  15. Aaron says:

    Which way do you prefer to have the BBF setup?
    I have an XTi that offers 2 ways to set it up.
    The first completely separates shutter and focus.
    The second keep the shutter button doing af and shutter release with the BBF button stopping re-focus.

    Thanks for the great info.

    Aaron

  16. Hey Aaron. You want to completely split the functions. That’s going to give you consistent results and will ‘train’ your fingers and mind to work this way, regardless of what BBAF camera you set up. Good luck!

  17. RJ says:

    Learning how to use the back button autofocus is quite useful to maximize the use of your DSLR or any high end camera. This is particularly useful for those who are still exploring their cameras as well.

  18. Martin Lewis says:

    Superb. Thanks for sharing.

  19. Bert says:

    THanks for this tip on BBF. I’m so new to photography but have always LOVED looking at photography and enjoyed taking pictures. I am taking a few courses and am ready to eat up any information I can to learn new and helpful information.I just bought the Nikon D7000 and am really excited about it! Bert

  20. Chris says:

    I just found this tip, who knew that function was on the camera the entire time i’ve owned it. It just makes sense to use it this way!

  21. Just came back from vacations , and I fond this article . Most of my vacation photos with my kids in and out of focus have this problem .. I must learn this now.

  22. sean says:

    Thanks for the info. I tried it out for the first time at the zoo this weekend. I love photographing wild life. One problem I have had in the past is keying in on one animal and having other moving around. I found the Back-Button gave me great results.

  23. Jennifer Gan says:

    I’m using 50D, tried it before but found it awkward, and didn’t want to know more about it since I don’t shoot sports or action often. Now after quite sometimes, I became really interested in shooting flying birds and think this might helps a lot. I understand about Melissa’s explanation, yet I don’t grab the idea what makes it better than the front shutter button focusing.
    I’ve been reading this article. It’s like the thing is JUST THERE, but covered with fogs and clouds… Lol. So is one shot focusing isn’t suitable for BBF, then? I’ve been switching C.Fn IV-1 option 2 or 3 custom settings (knew the differences), went outside and shot, yet don’t get the idea. Now I’m kinda frustrated.
    Thanks so much for the explanation. ;)

  24. Jennifer,
    I don’t have one of those cameras handy to try, so I’m not sure you’re properly separating the focus (to the back button) and the shutter (in its regular spot). If you are, the huge advantage occurs when you want to press that shutter button: when your thumb lets up off the back AF, everything is LOCKED in focus…which you cannot ever do if it’s all tied up with the shutter function. The anecdote in the article about the hockey game explains it, I think.

  25. Sage says:

    I’ve enjoyed thumb-focusing on my low-end Olympus Evolt camera for years. It took me a few days to figure out how to set the option when I got an EOS and the button layout was less than stellar for the function – Olympus’ cheapest SLR has better menu options than Canon’s prosumer line.

    This is definitely essential for me, There have been many times when I didn’t want to focus on something that was within the AF points or my selected AF point and the Canon simply refused to take the shot because it didn’t think it was in focus. In my line of work a blurry image is infinitely more useful than no image at all so sometimes I just need get the picture, quality be damned.

    On the Canon I can also keep the shutter as an AE lock so I can hold the shutter half way to maintain exposure and re-focus with the button in the back. Now, if they could just allow you to assign functions to any button or create a larger, more ergonomic button for AEL/AFL on the back, I would be set!

  26. Sarah R says:

    I just switched and love it! I don’t know why I was so intimidated to try it. It’s option 3 under menu IV on my 5D Mark II. That way I can use the shutter button to spot meter, focus only with the “AF-ON” button, and then hit the shutter to capture the image. I shoot portrait photography and prefer to focus on the eyes, but meter off the cheek/forehead/skin.

  27. Max Young says:

    G’day Andrew: Just came across your post (for the first time) and yes, I have just started using BBF technique and it has transformed my usage of the EF 50L lens. Sensational.

    Thanks for the post.

    Max
    Australia

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