6D focus assist

[Jaysheldon]

Hi
Can I use an ST-E2 transmitter for focus assist on my 6D, or does it have to be an EX flash?

 

[Click]

Yes, you can use the ST-E2 transmitter for focus assis. The ST-E2, 600EX-RT, 580EX, and 430EX flashes have a focus assist lamp.

 

[Khalai]

Sadly, ST-E3-RT transmitter does not

 

[Jaysheldon]

Having done some more reading and testing, I take it all I have to do is go to Custom Function II/5 and enable IR AF assist beam only?
I tried disabling Flash firing in "External Speedlight control" as I found in this thread (https://www.canonrumors.com/forum/index.php?topic=2359.15), but my AF didn't seem to like that.