In this post, Steve Berardi from PhotoNaturalist talks about three ways to get better control of autofocus.
Sometimes autofocus can be really annoying. For some shots it’ll focus on the right part of your subject, but then the very next shot it may choose to focus on something far and away into the background.
Sure, you could avoid this problem by always using manual focus, but autofocus is great when you need to focus quickly or when you’re photographing a landscape and you need to focus on a certain spot in the scene.
Well, autofocus doesn’t have to be annoying anymore, because here are three ways to get better control of it:
#1 – Press your shutter button half-way to activate autofocus and then recompose
Set your autofocus point to the center spot, then point this spot where you want to focus and press your shutter button half-way (don’t press it completely yet) to initiate autofocus. Then, while still holding down the button half-way, recompose your shot and press the button completely down to snap the photo.
#2 – Switch to manual focus after autofocusing
Use autofocus as you normally do, but once it focuses on the right spot, just switch off autofocus on your lens to manual focus. Your lens will keep the current focus when you do this. This method works well when your camera is on a tripod and you’re taking multiple exposures from the same spot, like when photographing a landscape.
#3 – Use back-button autofocusing
Normally, your camera will autofocus when you press the shutter button, but with back-button autofocusing, you have to press a button on the back of the camera instead, giving you complete control of when autofocus is initiated.
With back-button autofocusing, you can just set the autofocus point to the center spot, then point that where you want to focus, and finally press the back button to automatically focus on that point. Now for all the shots you take from that position, that focus will be maintained (the camera won’t randomly focus into the background anymore).
You can do the same thing without this back-button autofocusing by switching to manual focus after the camera focuses properly, but using the back button saves time and this way you don’t have to constantly switch back and forth between manual and autofocus (which can inadvertently move the camera sometimes).
Back-button focusing is especially helpful for photographing moving subjects, like birds in flight or other wildlife: just switch on the continuous focusing mode, set the autofocus point to the center spot, and hold down that back button. Now you don’t have to worry about accidentally hitting the shutter button while you’re tracking the subject in your viewfinder.
How to enable back-button autofocusing: Unfortunately, this feature is called something different on each camera, so you’ll probably have to do some digging around in your camera’s manual and “custom functions” to find it. If it’s not labelled clearly on your camera, try changing the settings of the different buttons on the back of your camera (like the AE lock button).
About the Author: Steve Berardi is a naturalist, photographer, and computer scientist. You can usually find him hiking in the beautiful mountains and deserts of Southern California. Read more of his articles on nature photography at the PhotoNaturalist and follow him on Twitter.