The What, How, and Why of Back Button Focusing
Back Button Focusing is the ability to assign the job of focusing the camera to the AF-On button, instead of the shutter release button. If you are not currently using BBF, then you are pressing your shutter release halfway to focus, and then pressing it again when you have locked your focal point. When you switch over to BBF it completely eliminates the shutter button from having anything to do with focus. The AF-ON on my Canon 5DMiii is located here:
BBF can be used on any of your focal points. I find that BBF is most useful in Ai Servo (AF-C on Nikon) in continuous shooting mode. When I am shooting, I first toggle to my focal point in camera, and then press and hold my AF-ON button until I have sharp focus on my selected point. Your focus will remain locked until you press the AF-ON button again. A word of caution: just like shutter release focusing, when you BBF and you or your subject moves closer or further away you will need to refocus. BBF is great for focus and recomposing as long as the subject remains on the same focal plane. My thumb is always on my AF-ON button, and my index finger is always on my shutter release button. For a moving subject I hold down BBF and track my subject, and my camera will continually refocus on my subject until I let go of the button and lock focus.
How To Set On A Canon:
All DSLRs have a Custom Function for setting BBF (except the original EOS Rebel). Setting BBF is a Custom Function in your Canon Camera. The specific Custom Function depends on your camera model. For my 5D Mark III, I go to Custom Function menu screen 2=>Choose Custom Controls =>Choose the first option.
Below you will find a guide for Custom Function menu for recent Canon EOS models:
EOS Rebel T3: C.Fn 7 (option 1 or 3)
EOS Rebel T3i: C.Fn 9 (option 1 or 3)
EOS Rebel T4i: C.Fn 6 (option 1 or 3)
EOS 60D: C.Fn IV-1 (option 1, 2, 3, or 4)
EOS 7D: C.Fn IV-1 (Custom Controls — Shutter, AF-ON, AEL buttons)
EOS 6D: C.Fn III-5 (Custom Controls -- Shutter, AF-ON, AEL buttons)
EOS 5D Mark II: C.Fn IV-1 (option 2 or 3)
EOS 5D Mark III: C.Fn menu screen 2 (Custom Controls -- Shutter, AF-ON, AEL buttons)
EOS-1D X: C.Fn menu screen 5 (Custom Controls -- Shutter, AF-ON, AEL buttons)
How To Set On A Nikon:
It is my understanding that in Nikons the AF-On button is already turned on. But, if it isn’t working here are some quick instructions:
The AE-L/AF-L button can be programmed to function as BBF.
Menu=> Custom Setting Men => Controls => Assign AE-L/AF-L button => AF-On
Or, Menu => Set Button =>Assign AE-L/AF-L button => AF-On
Focus Control: Using BBF allows for you to lock your focal point regardless of what happens in the environment that you are shooting. For example, if you are at your son’s football game and you have him in the frame with the focal point locked, and your index finger is just about to release the shutter and boom another player enters the frame. No big deal! With BBF your focus is locked until you BBF again. Your shot will not be out of focus, and you have gotten the image you intended. However, if you had been using shutter release focusing, and your son was in the frame with your shutter pressed half way, and then another player entered the frame. Your camera’s auto focus system would re-focus, and therefore you would have lost control of your focal point and possibly missed the shot.
Focus Recompose: Using BBF makes the focus recompose method a breeze. For example, if you are shooting a series of portraits, you hit your back button to lock focus. Once your focus is locked you are free to recompose your composition and shoot as many frames as you would like without your AF system trying to refocus every time you recompose your shot. It really give you the ability to lock focus and then concentrate on the composition of your image. However, BBF isn’t just for the portrait photographer, it is beneficial to all photographers. It gives great control to the landscape photographer because a camera’s AF system isn’t always great at choosing the correct focal point in a landscape. Using BBF allows the landscape photographer to also choose the exact focal point they want (foreground, center, or background). And just like in the portrait, once focus is locked with BBF it allows the photographer to concentrate solely on how they want to compose the image.
Moving Subjects: Using your back button for focusing on a moving subject is amazing. As long as you are holding down the back button your camera is continually refocusing and tracking your subject on the exact focal point of your choosing. Also, by holding the back button down you are enabling your camera’s AF Continuous mode. This allows for you to spend less time worrying about your camera settings, because you will not have to spend time switching between one shot mode and continuous focusing mode.
Self Portraiture: Taking self portraits is undoubtedly a skill. However, using BBF makes taking a self portrait a little easier. You set your focal point with the back button, set your timer or grab your remote, and get yourself in the frame! Again, since you have locked your focal point with the back button, your focus will not change. As photographer’s we are all guilty of not taking photo’s of ourselves, but with this one little change, it will make getting yourself in the frame that much easier!
Is BBF for everyone?
In my opinion, using back button focusing is a must. It absolutely revolutionized my shooting and the images that I produced. Does it take some practice and getting used to? Absolutely! But, it makes nailing focus and sharper images so much easier to achieve. It also gives you abundantly more control over your focusing. If you haven’t tired it, I recommend trying it now! You will be glad that you did!