I have a Canon 1300D. I'm using back button by custom function to auto focus. I was just wondering if there's any way to also set any other button to lock AE while using back button to lock focus.
Yes, there is. If you set the custom function to
1, then the shutter button is the
AE lock button on half press, while the back button does AF.
Only in modes 2 and 3 there's no
AE lock available.