Back focusing with AF-ON: what about shutter button?

[thegios]

Question...
I prefer focusing with the back af-on button: bottom part of screenshot, blue circle myself same as red square canon suggestion.

But... I set the shoot button on lock exposure (blue circle on top) while canon suggests measuring (red square).

Why? What's the difference?

[Waddizzle]

The recommend selection does not lock the exposure, but you can use the [ * ] button to lock it.

The function that you have chosen immediate, and always, locks the exposure.

You can set the camera however you wish.