Hi jockwav,
I have the Canon 2X Extender Mk2 that i use on the 70-200 f/2.8 is mk1, and it gives great shots, slightly soft at the edges, but if you stop it down 1 stop,this crisps up. I have used this extender when i had the f4 version of the lens, but found it too restrictive stop wise, and...