Using new Canon converter with new lenses
FYI- You all may find this of intertest regarding the new converters and there use with the new telephotos and the new 70-200 f/2.8IS II
From Canon...
"To achieve the maximum benefits of this new processor, you need to ensure that you attach the lens to the Extender first, and then attach the whole lens and extender combination to the camera. This way the camera will see a combined "Lens + Extender". If you add the extender to the camera first the camera will recognise it, but will the newnot be able to deduce that a lens has been added to the front of it."
Additional info on the new converters and the new IS functionality can be found here
Best,
Chas