Until recently, I relied on half pressing the shutter to autofocus. Using just the shutter release button is a time tested way to achieve proper focus in a variety of situations. But, after reading an article about back button focusing, I figured I’d give it a try.
Well, after using it for a few weeks, I am totally sold on the process of back button focusing. Basically, it simplifies the whole autofocus process.
What is back button focusing?
To back button focus, the photographer uses a dedicated button on the back of the camera. Press this button, and the camera will autofocus. Release the button, and the camera will stop autofocus. That’s all there is to it.
Half pressing the shutter will no longer control focus. So, to achieve proper autofocus, simply press the dedicated button on the back of the camera.
Don’t confuse back button focusing with “back focus.” Back focus occurs when a lens incorrectly focuses behind the intended subject. Totally unrelated.
Some cameras have a dedicated button (labeled “AF-ON”) for back button focusing. Cameras without “AF-ON” can use alternative buttons. For example, on the Nikon D750, I use the “AE-L/AF-L” button:
To reprogram the “AE-L/AF-L” button on the Nikon D750, simply go into the custom controls (Letter F in the Custom Settings Menu). Then, under the “Controls” (F4) submenu, change the “AE-L/AF-L” button to “AF-ON”. Now you’re all set!
Check out this article for more detailed instruction on how to set up your camera for back button focusing.
Why would I want to try back button focusing?
For me, half pressing the shutter to engage auto focus can be unnecessarily frustrating. Suppose I want to lock focus on a subject, then recompose the shot. Once I recompose and press the shutter release again to fire a shot, the camera will refocus. Sure, I can press the AF-L button to hold focus the whole time I’m re-composing. But, why bother with that extra step?
Furthermore, I can’t count the number of times I’ve accidentally fired off a shot while half pressing the shutter release. With back button focusing, the “AF-ON” button is all you need to worry about. No more accidental out of focus shots.
Keep in mind that back button focusing is a subjective process. Some people swear by it, and others don’t care for it. Give it a try to see if it simplifies your focusing process.