RTFM

A new (to me) toy - a Canon 5D mk4. 

I have been thinking of a new camera for a while as the facilities on newer models are a distinct improvement on my Mk2 and having decided to stick with a DSLR rather than a mirrorless I bought a 2nd hand 5D mk4.  This one appears to have had minimal use, just on ~800 shutter operations and the manual, strap and leads were all still in their plastic wrappers. 

I'm a fan of back button focusing - and had to resort to YouTube to sort out how to set it up.  It appears I can have a separate focus set up on the AF-On button, another on the  star button, one on the shutter and in case that's not enough, another on the stop down button.  I've not yet figured out why I might want to do that ... probably never will!

This is the menu for the AF-On button, which is what I'm using on the old 5D mk2 but the choices are not quite so many :-)

In a moment of common sense - Canon have used the same battery, so my existing ones can all remain in use :-)

RTFM:  read the friendly manual