Back button AF is one of the polarizing topics that keeps coming up. I used back button AF with my Canon DSLR cameras for many years, but since the launch of the EOS R, I’ve drifted away to the point of not using it at all. It is time to look at how you work with a modern mirrorless and determine if back button AF is necessary at all.
Back button AF is where the camera buttons are reconfigured so that the half-press of the shutter no longer initiates focus, but instead the photographer presses another separate button to actuate AF. Conventionally this was a means to avoid switching from one shot to Servo focus. Set the camera for Servo AF, then press and hold the back button to focus and track a moving subject, press and focus then release to be able to recompose a bit like one shot AF. With subject tracking in mirrorless cameras you can recompose while tracking a moving subject in the frame using Servo AF. So maybe back button AF is redundant.
