Sure, to register the AF point; press the AF Point Selection button and ISO button simulatenously.
To un-register the AF point, press the AF point Selection Button and the +/- exposure compensation button (which is next to the ISO button) simultaneously.
You can register a custom point on the camera and assign a button to it. So, you can quickly pull that point up to have focus ready when need be. The problem with the 1DX set up is it stays illuminated when you're selecting a manual point and it can be annoying to say the least.
You can register a custom point on the camera and assign a button to it. So, you can quickly pull that point up to have focus ready when need be. The problem with the 1DX set up is it stays illuminated when you're selecting a manual point and it can be annoying to say the least.