Focus modes: how, when and why you need to change your AF settings
Picking the right AF mode for your subject is essential if you want sharp results. Most DSLRs come with one manual focus mode and three auto options, including single shot, continuous and an automatic mode that switches between the two. These auto modes all work the same way (lightly press the shutter release and the lens will focus) but each suits a different type of subject.
When to use single shot AF
Known as One-Shot AF (Canon) and Single-servo AF (Nikon), use this when you’re shooting static subjects. It’s the default mode, as it won’t let you take a picture until the camera gets something in focus. Once it has, the camera locks this position for as long as you keep a light pressure on the shutter-release button.
Single shot AF is perfect for most shooting situations. The picture will be sharply focused, unless you move closer or further away from the subject after locking focus.
When to use continuous AF
AI Servo AF (Canon) and Continuous-servo AF (Nikon) adjusts the focus as long as you press the shutter release. It’s the best mode to use when shooting 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.
When to use auto select AF
AI Focus AF (Canon) and Auto Select AF (Nikon) are ‘intelligent’ modes that switch from single shot to continuous autofocus when the camera detects a moving subject, and vice versa. It’s a good choice when you’re photographing unpredictable subjects – if taking portraits of a bird that might take off, for example.
When to use manual focus
Manual focus (MF) requires you to manually focus the lens by twisting its focus ring. It’s useful in low light photography, when the camera’s autofocus system can struggle, or when subtle focus adjustments are required, such as in close-up and still life photography.
When to use Autofocus Lock
All digital cameras let you activate the autofocus system by lightly pressing the shutter-release button, but many also feature an AF button that does the same thing. You can usually customise the operation of both of these buttons, such as removing the autofocus from the shutter release altogether or enabling the rear AF button to stop autofocus instead.
But why would you want to stop autofocus? If you’re tracking a moving subject and for some reason it becomes obscured, you can temporarily switch off autofocus to prevent the lens from refocusing.
How to set your autofocus for macro photography
Best camera focus techniques: 10 surefire ways to get sharp photos
44 essential digital camera tips and tricks
Window light photography: master still lifes on a budget
on Tuesday, November 13th, 2012 at 12:04 pm under Photography Tips.
Tags: camera tips, DSLR tips, focus modes, How to focus