Almost nobody focuses a camera by hand any more, and almost nobody changes the autofocus settings either. The camera arrives on its defaults, the defaults work well enough for a photograph of a stationary friend in good light, and most people never look further. The trouble starts the moment the subject moves, the light drops, or there is more than one thing in the frame worth focusing on — at which point the default is frequently the wrong choice, and the resulting photograph is sharp in the wrong place. This article covers what autofocus is, the modes and focus areas you can choose between, how the underlying mechanisms actually work, and when to turn the whole thing off.
What is autofocus?
Autofocus is the camera's ability to bring a subject into focus without your intervention. Several different technologies sit behind it, and which one your camera uses affects how quickly and reliably it works — but from the photographer's side, the controls come down to two decisions: which operating
