Autofocus isn’t a one-size-fits-all system, you still need to take some control over your focusing technique to maximise the success of autofocus for your chosen subject. Some methods of autofocus work better than others whether you’re shooting portraits, action or macro photography. Take some times to learn how about these autofocus sub-types and you’ll be taking sharp shots in no time.
1. AUTO-AREA AF/ AUTOMATIC AF POINT SELECTION: SUITABLE FOR LANDSCAPES
For beginners, and if you’re using a small aperture (such as f/8 to f/16), Auto-Area AF can work just fine as the scope of what will be in focus is broad. You’re allowing your camera to pick the active AF points to use and it does this by locking focus on the largest subjects closest to the lens. For landscapes, this is tends to be foreground interest such as rocks so as long as you've combined Auto-Area AF with a small aperture, you should get the image sufficiently sharp. It’s commonly referred to as the ‘point-and-shoot’ method, which if you’re reading this is likely to be what you want to step away from in a bid for better control. As soon as you open up your aperture (f/5.6 or wider) to give one element in the scene priority sharpness, Auto-Area is not the best solution as you cannot fully control what subject will be focused on.
2. SINGLE-POINT AF: SUITABLE FOR PORTRAITS
Single-point AF is the preferred method by many serious photographers as you can choose exactly where the lens focuses. We recommend using the central – most sensitive – AF point and to use the Focus-Lock technique if your subject is off-centre. You can also use your four-way control to select an AF point over the area you want in focus, but this is more successful with cameras that have many AF points. It's the mode to use for static subjects and when employing wide apertures for shallow depth-of-field as your focus has to be precise. When combined with AF-C mode, single-point AF often becomes Dynamic AF-Area, or similar, which functions in the same way but will track the subject it’s locked on to so to maintain focus of a moving subject. It may employ surrounding AF points to assist in focusing, too, in case the subject strays from the main AF point.
3. GROUP AREA AF: SUITABLE FOR TRACKING A SUBJECT AND PANNING TECHNIQUES
A hybrid mode that's a cross between Auto-Area and single-point AF, Group Area autofocus uses a small cluster of AF points instead of just one or all of them. You can control where the lens focuses in the frame and the camera will designate the five surrounding AF points to help focus the subject. It will still focus on the subject closest to the camera within the cluster of points but at least you have some control over its placement. It often works in collaboration with Face Detection (see right) when in AF-S mode and tracks a subject in AF-C, so long as it remains close to the five AF points, making it ideal for panning. By dragging the shutter, locking focus on the moving subject using Group Area AF and moving with your subject to track its movement, you should have a better chance at getting the subject sharp.
4. FACE-PRIORITY AND OTHER SUB-AF MODES: SUITABLE FOR GROUP SHOTS
Sometimes referred to as Smile or Eye Detection, Face-Priority is a common feature in entry-level DSLRs and mirrorless cameras when used with Auto-Area AF, as it biases the focusing towards facial features to make sure that they are focused on. If there is more than one person in the frame, it will prioritise the most prominent face in the picture and, if you’ve Smile Detection activated, the camera will take a shot when it sees the signs of a subject smiling, such as upturned mouth and wide eyes. It generally only works on mirrorless cameras, compacts or a DSLR in LiveView mode. Many new models now offer similar ‘intelligent’ modes that work with Auto-Area, too, such as Spot AF (Canon) that fine-tunes focus inside a focus point, Wide-Area AF and Subject-Tracking AF for use with video. Give it a go!
5. LIVEVIEW AF / TOUCHSCREEN
As the reflex mirror is flipped up in LiveView mode, the image is projected onto the imaging sensor to reveal the scene that you’d normally see through the viewfinder on to the LCD monitor. A rising number of cameras offer touch-sensitive preview screens, too, that allow you to focus the lens by touching the area of the screen you want in focus; it’s not very practical with moving subjects due to the focus lag. Focusing in LiveView mode, however, can aid critical focusing on static subjects such as landscapes, close-ups and architecture as you can zoom into the image and focus manually. You may also find that LiveView is sensitive enough to see through some ND filters to allow you to focus and compose without removing the filter. The downside of LiveView, however, is it drains batteries fast and can be difficult to use in bright light, but a hood loupe can help solve this.