Sometimes autofocus can really be 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 (this isn’t always easy to do with manual focus).
So, here are two ways to lock your focus and prevent your camera from autofocusing on the wrong part of your subject:
( 1 ) Set your autofocus point to the center spot, then point this spot at your subject (or a specific spot in your scene) and press your shutter button half-way (don’t completely press it yet). Then, while still holding down the button half-way, recompose your shot and press the button completely down.
( 2 ) 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. I use this method all the time with landscapes.
About the Author: Steve Berardi is a naturalist, photographer, computer scientist, and founder of PhotoNaturalist. You can usually find him hiking in the San Gabriel Mountains or the Mojave Desert, both located in the beautiful state of California.