Focus modes: what happens when you half-press the shutter button?

Focus modes: what happens when you half-press the shutter button?

Your digital camera has a range of different focus modes to help you focus on a variety of subjects in all sorts of conditions. To activate your autofocus you simply press your shutter button down half-way. But what actually happens when you do this differs depending on what mode you’re using.

Focus modes: what happens when you half-press the shutter button?

Single-shot mode
This is the best mode for everyday photography. You half-press the shutter button (2) to activate the autofocus, the camera focuses once and then holds this focus until you press the button the rest of the way to take the picture or until you release your finger.

Continuous AF mode
This is the best mode for sports and action photography. As soon as you half-press the shutter button (2) the autofocus is activated, but it stays active all the time until you release the button or take the picture.

Auto mode
Auto mode will automatically switch between single-shot or continuous modes, depending on whether the camera detects subject movement or not. It’s a reasonable fall-back for novice users, but it can be unpredictable and it’s usually better to choose the mode yourself according to what you’re shooting – this is the best way to make sure the camera is going to react in a predictable manner.

AF-On button: ‘Back-button focusing’
Pro DSLRs have a button on the back, such as the ‘AF-On’ button on our Nikon D800. This takes over the AF from the shutter release – it’s a technique that sounds odd but makes sense when you try it. You can use it for single-shot AF, but it’s more often used for moving subjects in continuous AF mode.

SEE MORE: Back button focus made easy


Best camera focus techniques: 10 surefire ways to get sharp photos
How to focus your camera for any subject or scene: free photography cheat sheet
Autofocus point options: what subjects should each be used with?
Focus modes: how, when and why you need to change your AF settings