Quick Tip: Learn to Use Back-Button Autofocus
Are you a 'back button' autofocus shooter? Here's why you should be. (Copyright 2009 / Andrew Boyd)
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!
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 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. Thanks!–DiscerningPhotog
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!
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.
[Reply]
DiscerningPhotog Reply:
January 12th, 2010 at 11:12 am
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!
[Reply]
Been rolling with this method for a while now. It takes half an hour to get used to.
[Reply]
DiscerningPhotog Reply:
January 12th, 2010 at 1:32 pm
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!
[Reply]
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!
[Reply]
DiscerningPhotog Reply:
January 14th, 2010 at 1:49 pm
Excellent! You won’t be sorry, just give yourself time to really learn it.
[Reply]
I’m a convert…my play cam has no BBF. I find myself confused, like a caveman photog……lol.
[Reply]
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?
[Reply]
Cara Reply:
August 16th, 2010 at 1:08 pm
I figured it out! It has to be activated/enabled in Custom Functions (#9 on the Rebel XS)
[Reply]
DiscerningPhotog Reply:
August 16th, 2010 at 6:17 pm
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.
[Reply]