Focusing techniques

SPOT-ON FOCUSING IS A MUST TO ENSURE SHARP RESULTS WHEN SHOOTING ACTION

FOCUSING IS MADE all the more difficult with action photography because as well as dealing with a subject in motion — moving targets are always harder to hit — you’ll often be using a telephotolens at its widest aperture, which means there will be limited depth-of-field and hardly any room for error. Depending upon the type of subject you’re photographing, there are two commonly used focusing techniques that can be used to put the odds of successful focusing in your favour — prefocusing and follow-focusing.

PREFOCUSING

Prefocusing involves focusing on a point you know your subject will pass, such as a corner on a racetrack, or a running race in school sports day. All you do then is wait until your subject approaches and trip the shutter to take the shot.

It’s important to shoot just before your subject snaps into focus because your brain takes a fraction of a second to tell your finger to hit the shutter release, then there’s another fractional delay before the shutter opens and the exposure is made. If your subject is already sharp when you hit the release, by the time you do, it may have passed the point you prefocused on. The faster the subject is moving, the longer the lens focal length and the wider the aperture, the more likely this is.

If you’re using autofocus, set single-point AF and single-shot mode, partially depress the shutter release to lock focus on the chosen point, then hold it down until you’re ready to fire. Alternatively, use the AF-On button, if your camera has one, to lock focus so you don’t have to keep the shutter release partially depressed, or manually focus the lens on the predetermined spot. Use continuous frame advance to maximise the chance of capturing the subject in focus.

FOLLOW-FOCUSING

Follow-focusing involves tracking your subject with the camera and continually adjusting focus to keep it sharp so that when the action reaches it speak you’re ready to capture it. This approach is better suited to unpredictable subjects — such as football.

Before the days of autofocus, follow-focusing required skill because you had to adjust focus manually. Now, modern AF systems are so quick and accurate that even novices can achieve perfect follow-focusing. Set Servo AF so the lens adjusts focus continually, and select a focus point that allows you to keep the chosen part of your subject in focus. The latest DSLRs have loads of AF options, with focus-assist points, face recognition and other features that make it easier to achieve perfect focus.

It’s worth practising follow-focusing to find out how quick your camera’s AF system is — you should be able to shoot rapid sequences of images and get each one sharp. It’s also good to get used to changing the AF point with the camera at your eye, so you can adapt your approach quickly and ensure your lens focuses where you need it to while you’re tracking a moving subject.

Other focusing options

SELECTIVE AF POINT GROUPS

If you’re using a more advanced DSLR, it most likely boasts a huge number of AF points. If so, it’s worth checking to see if it allows you to select smaller groups of AF points(eg groups of five, seven or 11 points), as this localised set-up improves AF tracking.

BACK BUTTON FOCUS

An increasing number of DSLRs have an AF-On button on the top right of the camera’s rear. Its function is to allowyoutofocusindependently of pressing the shutter button and is a set-up favoured by many pros.

TRAP FOCUS

This is a facility that’s only available on a small number of DSLRs but it’s worth a mention. Trap Focus mode allows you to setup the camera so that the AF system is focused to a particular distance. Once the subject reaches it, the camera automatically fires the shutter release.

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