A lot of photographers have subscribed to the theory that, in order to auto focus your camera, you depress the shutter release button down halfway, wait for it to do it’s thing, then press the button down all the way to snap the photo. Yes, it does work and I’d even go so far as saying it even does an adequate job– so, why fix it if it isn’t broken? Simple. Because there’s a better way, a more efficient way to use auto-focus. It’s called back button focusing and, once you switch over, you’ll probably start to think the old way of auto focusing was actually a little bit broken.
What The Heck Is Back Button Focusing?
In a nutshell, you simply reassign the auto focus function to a different button that’s located on the back of your DSLR. On a Canon, you would typically assign it to either the AF-ON or AE Lock button, depending on which model you use. If you use a Nikon, it would be reassigned to the AF-On or AE-L/AF-L button, again depending on which model you have. On either brand, you can reassign what these buttons do by accessing them through the camera’s menu system. Since the process will vary between different camera manufacturers and models, just refer to your cameras user manual for the specifics.
Once you’ve got back button focusing all setup in the menu, to initiate auto focus on your camera, you simply use your thumb to press the new auto focus button while simultaneously using your pointer finger to fire the shutter. While it may seem like this actually complicates matters–we have to use two fingers now instead of just one–the benefits far outweigh the slight learning curve involved in making the switch.
Don’t Wait For Auto-Focus Between Shots
When you’re using auto focus via the shutter release button, every time you press the shutter, auto focus kicks in. That means, auto focus will go through its cycle every time you take a photo–whether you actually need to refocus or not. You can work around this by turning off auto focus, or by pressing the auto focus lock. Not a huge deal, but many times the need to refocus between shots is completely unnecessary and adding an extra step between each photo takes time. Time that could potentially cost you getting “the shot”.
With back button focusing, however, you can focus once and shoot repeatedly until you actually need to re-focus–in which you case, you just press the back button. You could also manually adjust the focus, if you prefer, without having to worry about it resetting as soon as you press the shutter release.
In shooting situations such as sporting events or fast action settings, where you find yourself constantly having to refocus to keep up a moving subject, back button focus is especially useful. It allows you to take more shots, more quickly, which results in less shots being missed. Though each and every one of those shots will not have perfect, tack sharp focus, you have to ask yourself which is better: having a slightly out of focus shot of your child scoring the game winning point, or having no photo at all (which is more likely to happen if you’re waiting on auto-focus to finish adjusting before you can even snap a photo). And, to that end, you’re percentage of getting sharp photos with back button focusing during action shots will actually increase, especially with some practice.
About That Learning Curve…
It’s real. And the longer you’ve been accustomed to using the shutter release as an auto focus trigger, the more awkward you’re likely to find the back button focusing setup. But that could be said of just about any task or process that you’ve only done one way your entire life, then suddenly decide to try a different way. That being said, the learning curve isn’t horrible. It’s actually pretty doable. After a few sessions, I’m willing to guess you won’t wan’t to go back to the old way!