Matthijs Claessen , Jun 27, 2011; 06:45 a.m.
Note that with some brands the aperture change by the extender is not communicated. The AF will be operational.
This can also be done with Canon by taping off some of the contacts. (Canon advises against that but it works, or so I am told.)
The results with the x2 III extender aren't that bad by the way. (With the II they're less good. See the mouse over.)
Kind regards, Matthijs.