Quote Originally Posted by Fast Glass


The 70-200mm f/2.8 works with a 2x extender, that make.s a f/5.6 aperture which your 7D still autofocuses at.


I beleive he was talking about using the 70-200mm f/4L with the 2x extender, meaning f/8 and no AF except for the center point on 1-series bodies.