Auto focus on Canon 5D mark II using 2X extender not working

[jGordon24]

I have a 5D mk II and 2X extender, 70-200 F4 L and 24-105 L  and the auto focus will not work. Only works in manual  mode. Is there a extender that will work with my camera? I also have a 50D and  a 5D same results. Please help, thank you. Plan on buying a 400mm L and a 70-300 L  will it work with these lens?

[diverhank]

Not sure if you wanted to delete this post or not, with the strikethough font.  Just the same...the reason you can't autofocus (AF) is because with the 2X, you lose two f/stops, which renders your f/4 lenses f/8.  The 5DII can only AF below f/8.  There are some extenders that will allow you to AF because it won't report the f/8 to the camera.  The AF result may not be any good though.  You might try taping the pins.   I know that you can tape the left most 3 pins on the lens side of the extender for the 1.4X but not sure it would work with the 2X (I don't have the 2X as I think IQ suffers too much with any 2X).