One of the most common queries we hear from photographers is, ‘What AF mode should I use?’ While there’s always nuance to a question like this depending on what you want your picture to look like, there are some general rules to follow when starting out (see The right way to set up your camera).

The two basic AF modes are Single and Continuous, often also referred to as One-shot and Servo. In most cases, the Single AF mode works best because autofocus locks onto its target when you apply a light press to the shutter release button and remains fixed while you maintain the light press, until fully pressing the button to take your shot.

Continuous AF mode is better for moving targets, such as kids running around, because focus continually tracks subjects. Below we’ve provided four common subjects and suggest the optimal AF mode to use in each situation so hopefully the next time you find yourself shooting one of these subjects you will be prepared to work quickly.

What is the best AF mode? See below…

Portrait perfection
For portraits, use the Single or One-shot 
AF mode and switch to a single AF point, which you should line up with a subject’s eye.

Moving targets
In Continuous or Servo modes, autofocus will keep tracking moving targets, even while the mirror is flipping up, until the shutter opens.

Sporting action
Continuous AF might not keep up with speedy targets, so switch to Single AF and pre-focus on a place the target is moving to.

AF points
Single-point AF usually gives greatest precision, but multi-point AF (Dynamic area) 
is good for tracking erratically moving targets.

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When you look through your SLR’s viewfinder and half-press the shutter button, you’ll see the multiple autofocus points flash when they’ve achieved focus, and you may also hear a beep – depending on the make and model of your camera. These cues are designed to help you take sharp photos. However, if you shoot using basic shooting modes (such as portrait, landscape, sports, and so on), most SLRs will automatically select the AF point, and will then use this AF point to focus on what it thinks you want to focus on – usually the thing closest to you, which might not be what you want to be in focus at all!

Points of interest

However, one of the many advantages of using an SLR is that you can control what your camera focuses on by selecting your AF point manually. This means – when shooting portraits, for example – that you can focus on one of your subject’s eyes, even if it’s off-centre in the frame. The number of focusing points you have varies from camera to camera. The Canon EOS 1100D, for example, has nine AF points, the Nikon D5100 has 11, the Canon EOS 7D has 19, and the Nikon D7000 has 39.

Control the focus

To manually select individual AF points, press the AF Point Selection button on your camera and then look through the viewfinder. Use the top dial, crosshair buttons or joystick to cycle through each AF point until the one over your chosen subject is highlighted. Half-press the shutter button to lock the focus, then fully press it to take the picture.

Helpfully, the AF points are placed on (invisible) vertical and horizontal lines at points one-third into the frame, so they can also help with composition when it comes to the rule of thirds – use them as guides for placing the subject in the frame. Note that if all the autofocus points light up at the same time, you’re on Auto Point Selection.

Single Point AF

This mode is best used when shooting a portrait, say, or any subject that stays relatively still. It enables you to select a focus point manually. By default, the centre focus spot (which is the most accurate) is used for focusing in single point autofocus.

Dynamic Area AF

This mode is perfect for shooting fast or erratically moving subjects. Some SLRs have up to 50 autofocus points – you choose one, but if the subject moves away from that point, the camera will continue to focus using one of the adjacent AF points.

Single-Servo/One shot

This is the most commonly used autofocus mode. All you need to do is point the camera at the target, half press the shutter-release button and the lens will focus. Crucially, the focus point will remain locked for as long as you maintain the half press on the shutter release button, enabling you to recompose the shot while keeping the selected point in sharp focus. You can only shoot once the focus is locked, but you can usually override this with a setting in the camera menus, should you wish to.

Continuous/AI Servo

This is more suited to moving targets, such as sports or wildlife subjects. The main difference between this and one-shot autofocus is that the lens continuously focuses on your subject. The autofocus system tracks the subject to ensure that it’s sharp in the captured image.

By default, continuous mode enables you to take a shot whether focus is achieved or not. There are limitations, such as in motor sport, where a car comes towards you at a higher speed than the autofocus can keep up with. In situations like this, it’s best to pre-focus in one-shot mode.

Auto-Select/AI Focus

In this ‘intelligent’ autofocus mode, often referred to as ‘auto-select’ or AI Focus, the camera’s autofocus system automatically senses whether an object is stationary or moving, and then switches between one-shot and continuous modes.

Manual

Single-frame shooting

The camera exposes a single frame each time you press the shutter release. This is best used for still subjects such as landscapes and portraits, where you don’t need a burst of frames to catch a fleeting moment.

In this mode, your camera will fire off shots
at its maximum frame rate for as long as the shutter button is held down. It’s ideal for sports, but you need a memory card with a fast write speed for long bursts.

With typical options of two- or ten-second delays, the self-timer mode can be used to fire the shutter remotely when, say, your SLR is mounted on a tripod. This enables you to press the shutter before positioning yourself in the shot, or to reduce camera shake.

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