Most photographers auto-focus the traditional way: press the shutter down halfway, then compose your shot and pray your subject doesn’t move around. Or press down halfway and quickly take the photo in the same second. But Steve Perry of Backcountry Gallery is promoting a different method–one he says “makes auto-focus much easier to manage”:
Your camera should have three AF modes. (Note that Perry is working with a Nikon camera; Canons and Sonys use slightly different terminology, but the gists of each are the same.) The three modes are as follows:
Perry recommends using back-button AF. Again, the term “back-button AF” only applies to certain Nikons, like the Nikon D800, which offers a literal button on the back of the camera that says “AF-On”. (Any camera can designate a back-button to AF, though; the Nikon D5100 has AE/AF Lock; Canons use their asterisk button.)
You have to activate the system first, though, by setting your camera on AF Continuous, then going into the “custom settings” menu, finding “AF Activation” and selecting “AF-On only”.
Now you’ll focus differently: when you want to focus a shot, hold the AF-On button rather than the shutter (which now only takes a photo), and release the button to lock your subject in focus. You can then freely compose your shot and your subject will stay in focus. If it’s moving, you can simply hold the AF-On button down and follow it, the same way AF Continuous works.
Perry lists off three reasons why this AF method is better than the conventional one.
Perry ends the video by warning that most people will find this system counter-intuitive, maybe even mess up a few good shots. He recommends sticking with it for a few weeks to realize its advantages, and testing it out on less important shots to get the hang of it. Anyone who’s converted can tell you: they’ll never go back.