I have recently switched cameras to a Canon EOS 1300D and I am unable to find how to enable back button focus. Does anyone know how to enable it?
It's all on page 265 of the Canon EOS Rebel T/EOS 1300D Instruction Manual:
Set [C.Fn IV: Operation/Others] → [C.Fn-8 Shutter/AE lock button] to option [1: AE lock/AF].
Anytime Canon puts a slash dividing two buttons in a custom function menu, the listed options on one side of the slash are assigned to the button on the same side of the slash in the menu item listing.
In this case, option [1: AE lock/AF] assigns AE lock (auto exposure lock) to the 'Shutter' button and AF (autofocus) to the 'AE lock' button.