The Limits of Autofocus

Maleo (Macrocephalon maleo) Angry male, Indonesia

I spent much of the last few weeks in the company of wild maleos, an endangered bird species on the island of Sulawesi. It was hot, hard work, but I felt privileged to spend time in the company of a fascinating, lively, and slightly weird bird. As I mentioned a few days ago, maleos gather near the coast to lay their single, enormous egg in the hot sand, there to be incubated by the heat of the sun.

They spend most of their time digging,  which allowed me many opportunities to capture that behavior (see below) but there was more going on as well. For birds that share a communal nesting area, these guys don't seem to get along very well!  When they weren't digging their own nests, the males of each maleo couple spent a lot of time chasing away other birds that had the temerity to try and nest too close. This process put the birds in some pretty striking poses, like this male huffing himself up to look big, and scary, to another bird that had strayed into "his" area.

Working with a 600mm (equivalent) lens in a tiny blind, I managed to get some good close-ups, but was constantly plagued by the shallow depth-of-field at that focal length. Essentially, I had to lock onto the face (since even if nothing else is sharp, the eyes must be) with my auto-focus and try and stick with it, as the birds ran circles around me and one another. In the end, I lost more pictures than I got - including some spectacular aerial fights that I just couldn't lock onto. But I still managed to come away with some nice behavioral coverage.

Autofocus has been an enormous boon to wildlife photography, as any of you who remember manual focus will testify.  Many of the crisp action photos we see today would have been virtually impossible when I first got started - you felt lucky to get one picture of a moving animal on a roll of film in focus. Now, with focus tracking, you can get entire sequences of birds in flight, or animals on the run.

But even the best autofocus can't work miracles. I have yet to use a camera that works as fast, and as flawlessly, as the human eye: maybe I'll live long enough to see that...  In the meantime, for this shot of a charging maleo I had to lock on to the eye of a moving bird coming right towards me, his head slightly off-center.  I got it, but I missed a dozen others as my autofocus struggled. Believe me, there is nothing so maddening to a photographer in the middle of the action as an autofocus that is searching in and out for something - preferably a hard edge - to lock onto. At moments like that, a fraction of a second can seem an agonizing eternity.

My autofocus clearly did not like the bird's black feathers, and the various predictive tracking modes didn't work well in this situation. So I was left with placing my focus point manually - a high-risk enterprise with a moving animal. In the end, I got some shots I'm happy with, but I keep thinking of those I left behind...

Dig, dig, dig

Nikon D300 with Nikkor 200-400 lens


    Kevin, I am so glad you posted this article. I recently had a heck of a time trying to shoot some camels at a Christmas parade (NOT the same challenge as shooting in the wild to be sure). I tried both auto focus and manual focus. I thought my frustrations came totally from my lack of experience. I may have captured one usable image that evening. I was wracking my brain trying to figure out what I could have done differently.

    Rebecca, I think it is the fate of wildlife photographers to beat themselves up for the shots they miss rather than feeling good about what you got… I have some spectacular maleo shots – except that they’re completely out-of-focus. (And not blurry enough to be considered “creative!”..:))

    Yes, autofocus operates on contrast, it needs some sort of definition to work properly. Shots of the sky, of water – and particularly on animals without strong patterns or edges are hard (especially when they’re moving).

    In some situations it is helpful to take your camera off of Continuous Focus and put it on Single Focus. This allows you to lock onto a subject and it will stay in focus as long as you keep your finger down (and stays the same distance away..) This wouldn’t have worked on my “charging” bird shot, but it can be one solution when your autofocus is struggling.

    Either way – it’s not you. Even with the best of cameras and focus systems, technology has its limits. Good luck!

    Thanks Kevin for your article. I am a budget shooter and I have fallen in love with owls and got a Sigma 120-400 f/4.5-5.6 OS HSM on my Canon 40D to capture them in flight handheld. I am so glad to have read your article. Even after I practiced shooting in bird shows and in the field, my successful rate is very low in the 2-5% range with sharply focused result while I shoot mostly in the high-speed continuous drive mode. I have been thinking seriously about upgrading my camera body to 7D reasoning my lack of success is partly due to my gear. I understand both the gear and skills play a big part and knowing the top lens, such as the Nikon 200-400 F/4, still calls for manual focus definitely open my eyes. By the way, do you have any recommendation on how I could improve? There is an unusual occurrence happening now that a number of snowy owls are showing up where I live. I don’t want to miss out on this opportunity!

    Hey Gary,

    Thanks for your comment. I am a Nikon shooter so I can’t honestly assess the best AF lens/body combo for a Canon user – maybe other readers can weigh in. (I do know that there was a Canon guy next to me part of the time I was in Indonesia – and he was having trouble, too!)

    But some lenses clearly lock on faster than others: my Nikkor 300 f2.8 is super-fast, while the 80-400 is maddeningly slow. In my experience, zoom lenses also have slower AF than prime lenses, and both are slowed down by the use of teleconverters. This could be part of the problem with your Sigma lens, although again – I haven’t used it. Have you noticed whether your 40D focuses faster with other lenses, like a 70-200mm?

    Also, does your lens have image stabilization? If you’re shooting birds in flight, chances are your shutter is at least 500-1000/sec to stop the motion. If so, turn off your IS/VR – you don’t need it, and it may actually be slowing down your focussing.

    Finally, tracking a bird in flight with a long lens is simply one of the hardest things to do. I have my best luck when the bird is flying in an arc perpendicular to my lens so that it remains more or less at the same distance: then it’s just a question of locking on and allowing your Continuous focus mode to get you through.

    Good luck – I envy you the Snowy Owls!

    Great advice Kevin. In fact, I have been using stabilization with shutter speed around 800-1250/sec. I thought the longer the zoom is (400 vs 200mm), it is natural it takes more time to focus. I do find it focuses faster with my 70-200 F/4L on my 40D. I don’t have a tele-converter yet but is consider getting the 1.4x but worries it further slows down the focusing given my lens is not fast like a F4 or F2.8. (well, actually it will become manual focus only with tele-converter attached to my Sigma.) I will definitely try to switch off the stabilization. Thank you again.

    Your photos are really awesome!

Leave a Reply

Main Menu