Back Button Focusing – Easier than you think!
In this article you’ll learn what back button focusing is, and how to back button focus for Canon and Nikon cameras.
What is back button focusing?
The camera usually focuses when the shutter button is pressed half way down, and then the photographer takes the picture when the button is pressed in fully. Back button autfocus makes it so the shutter button doesn’t control the focus activation at all, but instead assigns another button on the back of the camera (hence the name) to activate focusing on the camera.
Read the article here: Back Button Focusing