Why I Prefer Back Button Focus
This is my second blog post in a week and eyes are almost bleeding. I really only post something if I have something to say, I’m not a great writer so I generally avoid this sort of thing like the plague. But today, I chanced across a weird post from PetaPixel on Facebook titled “Is Back-Button Focus Becoming an Outdated Photography Technique” and I felt compelled to put some words down, at least from the perspective of a sports photographer. So without any further ado, here’s why I prefer back button focus and how to use it.
The writer argues there are two ‘popular’ reasons to use Back Button Focus (BBF):
The first being that mere mortals like us can’t emotionally deal with a single button having two functions, such as the shutter release also activating focus. Thus we need to separate them in order to maintain our sanity. This sounds dubious to me and very condescending. There are things I have trouble emotionally dealing with; Death being one. Bad coffee is right up there. Leopard skin print, definitely. Fitting your lens hood on backwards, please stop doing that, it’s not a baseball cap. Of course, let’s not forget the boring mirrorless vs DSLR debate, that alone will have you committed. But one little button having two functions isn’t one of them, and I would hope that most of you agree that we’re stronger than that!
The second ‘popular’ reason and one that is actually valid, is the ability to focus and recompose shots without having to refocus again after the shutter is released. Especially if you use continuous focus mode which is called AI Servo AF on a Canon or AF-C on a Nikon. But there are many other reasons too that they don’t even touch on.
It goes on to argue that technology as moved on, we have more focus points now and this eliminates any need to focus and recompose with no compromise. I suppose this is true of the modern mirrorless point and shoot cameras we have these days. But the writer seems to forget that there are many different genres of photography, some benefit from BBF and others don’t. But most importantly, it is personal preference. For sport, we use the centre (sorry American people, that’s how we spell ‘center’) focus point most of the time, we don’t have the luxury of time to move the focus point around for composition on the fly. So 1,000,000 focus points is a moot point. I feel I’m overusing the word ‘point’ a little. Moving on.
Given I shoot sport, here’s my thoughts on BBF (No, not BFF – that’s different) for sport shooters and please keep in mind that it’s just my opinion, my personal preference, there’s no right or wrong. I know some outstanding shooters, far better than I am and far more experienced, who do not use BBF, yet we’re still BFF’s! However, most seem to and there’s good reason:
THE BASICS OF HOW TO USE BACK BUTTON FOCUS
Your camera is set up with default settings out of the box. One of the main settings that’s become the standard for all cameras is how they focus. You press the shutter halfway, the camera focuses, press it all the way and the camera sets exposure and releases the shutter.
Back Button Focus simply removes the focus actuation from the shutter release and instead assigns it to a button on the back of your camera. It’s usually labeled AF-On but it depends on your camera.
It seems counter intuitive but there are some good reasons why you might consider a change. I won’t go into all of them, just what I consider important for sport.
YOU CAN SWITCH EASILY BETWEEN SINGLE AND CONTINUOUS FOCUS
All cameras have at least two auto-focus modes (some have three); Continuous AF and Single AF. Some Canon’s offer AI Focus AF which automatically switches from Single to Continuous as required and it’s silly – don’t use it. Changing them from one to the other is time consuming and tedious and impossible on the fly. Although you can customize other buttons on the camera to flick between them, but now we’re over complicating things.
Each mode has its pros and cons. Single AF is useless when your subject is moving and Continuous AF is no good if your subject and active focus points don’t align, preventing you from focusing and recomposing.
Back button focus essentially gives you the best of both single and continuous AF modes, at virtually the same time. All you need to do is have your camera constantly set in continuous AF mode. Simply press and release the back focus button to focus on a still subject (and recompose as desired) or press and hold to track movement, releasing only if your subject stops moving.
As sports shooters, this gives us a huge advantage both in ease of use and efficiency. If we accept that the premise of sport shooting is to capture the moment, that split second of action or emotion, the last thing we need to worry about is fiddling with settings. Sometimes our subjects are moving, other times they’re stationary. We shoot the action on the track or field, and we shoot the crowd, the coaches, and whatever else seems interesting at the time. Some move, some don’t. Having the versatility of being able to hold the back button for focus tracking, or hold and release for focus locking is the difference between getting the shot, nor not. Which brings me to my next reason to switch to BBF.
TRACKING & PREFOCUS
If you shoot sport, then you’re shooting moving subjects. Whether its cars or bikes travelling at 100 mph, or track and field, your subject never stops moving.
The reason I love BBF so much is the ability to pair it with Continuous AF mode for accurate and quick focus tracking in all situations.
Back button focus alone is beneficial, but if you frequently shoot moving subjects, you can really take your ability to nail focus up a notch or two by using continuous AF mode along with BBF. Continuous AF allows you to track moving subjects and keep them in focus. By continually pressing the back focus button, your camera will readjust focus as your subject moves. The series of images below highlights how critical it is to use continuous mode via the back button. These images were taken at the MotoGP when Dominique Aegerter almost high-sided his bike at Phillip Island. He saved it and continued to finish the race but the incident itself took place over less than half a second.
I had the camera trained on someone else and caught the action with my other eye. I shifted the camera onto Domi’s bike, kept my thumb firmly pressed on the back button to reacquire focus and track, and pressed the shutter and here’s the result:
Settings for all photos in the series:
Canon 1Dx
Canon EF 600mm f4L II USM
1/640 : f5.6 : ISO100
… and another sequence where BBF was critical to capturing the series:
Settings for all photo’s in the series:
Canon 1Dx
Tamron SP 150-600mm f/5-6.3 Di VC USD G2 @ 250mm
1/1000 : f6.3 : ISO400
Even though the subject was rapidly moving towards me and the plane of focus was constantly changing by the millisecond, by using back button focus and the continuous mode together, I was able to achieve excellent focus on an otherwise very difficult shot.
I could have captured this series without BBF, but it would have been much harder.
Can you use continuous auto focus with the shutter button as your focus button? Of course you can, but you lose the other benefits and the flexibility they afford you in all situations.
Other reasons?
There are other reasons its useful too. For landscape you can pre-focus on something in the scene without having to worry about switching the lens to manual focus.
For Motorsport, you can pre-focus on a section of track and capture the action as it passes by. Very handy for extremely high-speed work where tracking can’t keep up, or you’re using a lens that under performs.
Night photography too, cameras struggle and fail most of the time when focusing at night. Traditionally you would switch the focus mode to manual to prevent the camera from refocusing every time you press the shutter. Back button focusing can save you from fumbling around to find the switch on the lens by allowing you to focus manually at any point. Once focused, the camera will not try to refocus and you can try out various compositions.
You’re separating focus and AE lock. You lock focus on a moving subject by pressing the back button, track it, pick your timing and burst off a few frames, the camera will lock exposure when that burst happens, not when focus is activated. I shoot in manual but always with Auto ISO. When I half depress my shutter button, AE lock is activated, so I stay clear of it until the exact time I want that shot taken. Exposure is much more accurate that way and focus is always maintained.
I can think of many other reasons too but this is a post about sports photography so I’ll leave it here. Feel free to comment below if you agree or disagree, I’d love to hear your thoughts!
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Dave shoots for Speed Media Image Agency, a professional photo agency providing coverage of all sports, events and photojournalism. We photograph for international, national and local media agents, including Getty Images, Icon Sportswire, AP, News Corp, The Times, ESPN and CNN. We have a team of commercial photographers ready to shoot for sport teams and sponsors.