Learning wildlife photography – When to use manual focus

Posted on 11. Mar, 2009 by Paul Burwell in Everything, Techniques, Wildlife photography

Le Conte's Sharp-tailed Sparrow perched on a branch

If you’re a regular reader of my blog you know that I’m a big advocate of using your camera’s autofocus system whenever possible.  While there are better and worse  autofocus systems and the debate as to whether Canon/Nikon/Sony/Olympus/Pentax have the best autofocus performance will go on forever, in reality they all have very useful autofocus systems that will usually achieve very acceptable results.  There are, however, a few circustances where trying to use autofocus will cause more problems then it solves.

Marsh Wren perched on a branch

The immediate situation that springs to mind is when you are attempting to photograph a small bird, like a warbler, sparrow, flycatcher, etc. as it flits around a bush or tree searching for bugs.  Most autofocus sytems work by trying to detect areas of contrast and then adjusting the focus on the lens until that contrast becomes as sharp as possible.  That’s one of the reasons why autofocus has problems in low light conditions because the low light reduces the contrast of the scene making it difficult for the camera’s autofocus system to find any point of contrast to lock in on.

Savannah Sparrow perched on a branch

When a small bird is darting around a bush or any other setting with a lot of “stuff” in the background, the camera’s autofocus system can get confused by all those contrasting areas shifting across the viewfinder and will often choose the wrong thing to focus on as you move your lens to follow the erratically moving bird.  To solve this, I acquire the initial focus on the bird using autofocus and then switch the autofocus off.  I’ll make the small manual adjustments to focus that are necessary as the bird jumps around the bush.

Before I discovered this technique I missed a ton of shots as I’d have kept the bird in the viewfinder as it moved around, but the camera’s autofocus system decided to focus on a branch or leaf in the background instead of my subject.  If I had a swear jar attached to my camera, I could probably have bought myself quite a nice present.

The next time you get into a situation where you have a relatively small subject moving around against a busy background, consider turning off the autofocus.  I’m betting you’ll get a few more keepers and a bit less money in the swear jar.

Have some tips on photographing in this type of situation?  Please share them with the rest of us.

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Tags: autofocus, background, busy, cluttered, image, learn, learning, manual, Photography, sharp, Wildlife