Mastering Autofocus  

Mastering Autofocus

It was 1985 when Minolta revolutionized the world of photography with the release of their first autofocus SLR—the Maxxum 7000. With autofocus in its infancy, my ability to manually focus was better than what that camera and lens combo could provide. Fast forward to 2017. There’s no way I can outperform the autofocus systems in today’s cameras and lenses. But even with the amazing advancements, there are photographers who don’t take advantage of all the available AF features. Given the paces through which I put autofocus to the test photographing birds in flight and other fast-moving subjects, it behooved me to learn every nuance of my AF system. Let me share what I’ve found so you can get the most from yours.

Set The Proper Focus Point: Inside the viewfinder, small squares represent the active focus point. It’s essential the active point hovers over the subject when the shutter is pressed or else the camera focuses on a different plane—the plane over which the focus point is placed. Depending on what camera system you own, use either the main command or sub-command wheel to position the square over your subject. If the lens is wide open, be very accurate with where you position the focus point since the depth of field is narrow. For instance, if you compose a photo of a pregnant woman and the center focus point is on her belly, chances are her face will fall out of the depth of field if the lens is wide open. If this is the effect you want, excellent. Always be cognizant of the most critical plane of focus and move the AF focus point to that location.

Mastering Autofocus

Continuous or Single: Many DLSRs provide an Autofocus option that allows you to release the shutter even if the subject isn’t in focus. This is known as continuous release / AI servo / release priority, etc.—it depends on the camera brand you own. Continuous mode is best reserved for subjects that move erratically. I use this ALL the time for any moving subject. The idea behind it is that although you get a few out-of-focus images, the AF system catches up with the subject’s movement to provide sharp photos. The alternative is Single mode, which allows the shutter to release ONLY if the camera detects sharp focus. If a subject isn’t moving, it works great. All my landscape and portrait work is done in this mode. In Single mode, the camera determines if the shutter can be released. In Continuous, the shutter can be released whether or not the subject is in focus.

Initiate Focus From Far Away: If action comes toward you, lock onto the subject when it’s small in the frame and maintain focusing. In Continuous mode, the camera tracks the speed at which it moves and “learns” its pace. As it gets closer, begin to make pictures. Keep shooting until you cut off important parts of the subject. I do this ALL the time when I photograph birds in flight. If you know where the action will occur, prefocus on an object on the same plane. The camera will have a reference point from which to initiate focus so the lens doesn’t have far to search when it locks on the subject.

The Center AF Point is the Most Sensitive: For action shots, I use continuous focus and lock on the subject using the center AF point. The center point is the most sensitive point of the system. In Continuous mode, as the subject comes closer, I recompose the photo so the subject isn’t dead center in the frame. The beauty of Continuous is that the center focus point “hands off” the tracking to other focus points while I recompose the photo. It takes practice to do the recomposing, but it’s well worth the effort and result.

Mastering Autofocus

Use The Focus Limit Switch: Many AF lenses have a Focus Limit Switch. If the subject won’t come into close proximity, set the lens to the infinity marker. The reason for this is if the subject falls out of focus while you’re tracking it, it won’t unnecessarily search the entire range of the AF system. As a result, locking on again takes less time. The AF limit switch is mostly found on longer telephoto lenses.

Turn Stabilization OFF: Image stabilization works great to steady the lens, but too many photographers leave it on all the time. Turn it off if you encounter the following:

  1. a) When photographing action, fast shutter speeds are necessary to stop motion. The fast shutter speed negates camera movement. With stabilization ON, it uses the gyros and eats up battery power.
  2. b) Image stabilization may slow down an AF system. If the action is fast, I want all the AF horsepower I can get, so I leave it off.

Incorporate the above techniques into your workflow and, hopefully, you’ll have many more keepers in the future.

Visit www.russburdenphotography.com for information about his nature photography tours and safari to Tanzania.

Photography is what motivates me to move through life in a positive way. Photography is ͞All About The Light͟ and it’s the first thing I seek out before I press the shutter. Optimally, I pursue great subjects in great light, but if there’s an ordinary subject in great light, I still press the shutter. I love to share the photographic knowledge I’ve accumulated and I hope my enthusiasm is contagious so I can motivate others to feel the same way I do about my photography.

8 Comments

    Thanks for this useful information. I have a question about “Center AF Point.” Do you use the single AF point and not a multipoint AF? I shoot Nikon and have the choices of single, 9, 21, and 51 point dynamic area auto focus. If I understand your article you recommend single. Correct? Thanks

    John – I use multipoint when I photograph action and single point when I photograph a stationary subject. The number of points to use when you chose multi depends on the subject contrast and size. I recommend you start with 21 on moving subjects and tweak your results from there.

    One of the things I have found useful when using my Sony A6000 to photograph in zoos is that the Continuous Auto Focus will track prowling animals behind mesh, and not re-focus on the mesh. Very useful!

    There is some pretty questionable information in this article, and that is as nice as I can write it. For example, continuous release is in NO WAY synonymous with release priority as is stated, and it isn’t true that these are just terms used for the same thing in different camera brands. You can use continuous release with either focus priority or release priority. In fact, I believe that every single sentence in that first paragraph is either completely wrong, so general as to be useless, or a personal statement (e.g., I use this all the time). I can’t believe that someone writing an article on auto focus could be so confused about the difference between focus/release priority and single/continuous release. They are completely different. I hope the author didn’t get paid for this misleading article, and I would recommend that everyone ignore it.

    Whoa, I just reread my post and I apologize for the tone!!!! I do think there are problems with the article as stated but I’m embarrassed about how I presented them; sorry Russ!

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