Finding focus

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Autofocus systems may have become more and more sophisticated over the past 25 years, but as Lou Coetzer explains, effort is still required from the photographer to capture the dramatic movement without a blur in sight.

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The story
I was recently on the Chobe River in northern Botswana with a group of very enthusiastic photographers from the USA. It was a late winter afternoon and my photographic boat was well positioned with the beautiful African sun sitting fairly low in the sky. Every photographer had a clear view of a nearby African fish eagle, which was showing hunting intentions. I’d jokingly told my guests that I had arranged with this particular eagle to take off from its perch at 4.20pm and lift a bream in a stretch of water lilies right in front of us. So when it all happened as predicted (albeit seven minutes early), why did only two of the eight photographers get any photographs of the action other than that of the eagle leaving its perch?

The challenge
Although professional autofocus systems have come a long way since the early 1990s, they still need some assistance from those operating them. The mistakes my crew made on this occasion are common when photographing birds in flight. When the fish eagle, with its predominantly black and brown profile, dived from its perch against a similar coloured background, the autofocus cameras lost focus due to the lack of contrast. So did my D800! Even when there is a strong contrast between the bird and the backdrop, such as against a blue sky, things can still get lost. If the camera’s autosensor is not placed exactly over the bird, which is not as easy as it sounds, autofocus will be lost immediately and not regained before the action is over.

The solution
Immediately stop focusing when your camera loses autofocus on a moving subject. If you don’t, your autofocus will continue searching the background and won’t regain focus. Next, quickly regain the subject in the viewfinder before reactivating the autofocus. If autofocus is regained and lost again, repeat the process. When properly locked on the subject most of today’s DSLR autofocus systems will do a great job of focus tracking.

The images
When the African fish eagle took off from its perch my autofocus was perfect. However, focus was quickly lost as the bird plunged toward the river. By stopping focusing and finding the bird in the viewfinder, I was able to regain autofocus the second the eagle lifted the bream out of the water. It then flew diagonally away from me, before turning sharply to the left and flying across my camera’s viewfinder towards its nest – my camera did not lose focus once during this flyby.

Extra tip
If the subject is so out of focus that you cannot see it through the viewfinder at all, focus on the ground directly below the bird. With this done, search for the bird in the sky and it should be fairly sharp in the viewfinder.

Learn more about Lou Coetzer, his images and the photographic-workshop safaris he runs at www.coetzernaturephotography.com

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