Quick C.FnIV Operations/Others Question

I have a 5DII and use the AF-On button to focus, using the center focus point. I want to place the center point on a person's face using spot metering, hold the focus and metering, then recompose and shoot.

Which one of the four options do I use under C.Fn IV?
Shutter button/AF-On button

0: Metering + AF start
1. metering +AF start/AF stop
2. Metering start/Meter + AF start
3. AE lock/Metering + AF start
4. Metering + AF start/Disable

I'm thinking I need to use #3, press the AF-ON button, depress the shutter half way, recompose, then shoot. Am I right? Is there an easier way.

This is very confusing to me. Can you recommend a website that explains it?

Thanks,
John

You want 2 or 3.

I used 2 on my 5d2 and use it on the 5d3 and 7d as well because I almost exclusively shoot in Manual mode so I have no use for AE lock.

If you do use AE lock then 3 would be the way to go.

If you use any that involve AF start being on the shutter button then when you go to take the photo after focusing with the AF-On button it is going to AF again, which you do not want.

It is also quite common for folks to swap the AF-On button with the AE-Lock button since that button is more conveniently located for back-button focus use.... (C. Fn IV -2 Enable)

This page helped me decide.

http://www.learn.usa.c​anon.com …ckbutton_af_art​icle.shtml