Focus Limiters: The Overlooked Switch That Can Reduce Autofocus Hunting
There is a switch on your telephoto lens that many photographers never touch. It sits in the bank of controls on the barrel, usually labeled something like FULL and 3 m to infinity, and it is one of the quickest things to check when you hit the most maddening autofocus problem there is: the lens racking back and forth through its focus range while the bird you wanted flies away.