Auto-focusing using 40d with extender on 70-200 4 IS?

Question

Is it possible to do auto-focusing(althou only center focusing) with canon 40d with 1.4 or 2x extender on 70-200 ?

Thanks

Answer 1

With the 1.4x extender, auto-focus is possible since it becomes an f/5.6 lens.

With the 2x extender, auto-focus is not possible on the 40D since it becomes an f/8 lens.  You would need an EOS-1 body to auto-focus with the 2x extender, or you would need the f/2.8 version of that lens to auto-focus on a 40D.