Camera College

New series: the complete guide to modern photography

What’s autofocus all about?

Discover the ins and outs of how your camera focuses – and how you can get even sharper results

Today’s cameras put a comprehensive set of autofocus controls at your finger (and thumb) tips, but there are essentially two simple steps you need to take regardless of how sophisticated or complex your camera is. First, set the focus mode to match the subject you’re shooting, then decide where you want the camera to focus.

There are typically three autofocus or AF modes available when you’re taking pictures through the viewfinder of an SLR or CSC: a single-shot mode for stationary subjects; a continuous ‘servo’ autofocus mode for moving subjects; and an automatic mode that switches between the two as and when the camera detects some movement.

Single-shot autofocus is the mode to select when you’re photographing subjects that aren’t moving. It won’t let you take a picture until the camera gets something in focus. Once it’s done this, the camera locks the focus distance in for as long as you keep a light pressure on the shutter release button, and the picture will be sharply focused unless you or the subject move.

As the name suggests, continuous autofocus constantly adjusts the focus as long as you keep your finger on the shutter release. As a result, it’s the best mode to use for photographing moving subjects. The focus position is never locked, and the camera will let you fully press the shutter to take a picture even if the subject isn’t in focus.