George Theodore, January 9, 2017
I’ve used Back Button Focusing (BBF) for a very long time. And my reasons are simple: (a) it locks focus, (b) the shutter button now has but one function – shutter release, (c) after achieving focus with BBF, I can touch up my focus manually if I choose, (d) it allows me to move around a little – I can even move my tripod – and as long as the distance between me and my focal point remains constant there’s no need to refocus and (e) if something crosses between me and my subject, my focus won’t change.
But, the one thing BBF will not do is guarantee a sharp image and I have enough not-so-sharp pictures to prove it. There was a recent post (I forgotten where) that stated BBF improves image sharpness – nonsense. You want a sharp image? Use good technique – tripod, solid surface, use of shutter release cable or other remote triggers or hand hold properly and at appropriate shutter speeds (for you). BBF has absolutely nothing to do with getting the image sharp. All it does is separate the functions of shutter and focus.
I also use BBF for wildlife – but the faster or more erratic the movement, the tougher it is to use. For example, I sometimes find it difficult to track birds-in-flight with BBF but that’s just me. In these situations, I’ll often revert to using the shutter release button to assist focusing.
I find more and more photographers using BBF. If you haven’t tried it, you should consider the benefits and give it a whirl. Cameras differ in how you set up BBF but it's basically using your AF-ON button to focus and defeating the focus function of your shutter button. Consult your owner's manual.