Help needed - borrowed canon 1.4 extender won't autofocus

[Jay Mlazgar]

I borrowed a canon 1.4 tele-extender to go with my canon 50 D and canon 400 mm L . The lens alone autofocuses great. When I attach the tele-extender, it does not autofocus on still or moving images - no auto focus at all. Used sport, Tv and Auto modes. Still no autofocus.

Don't know how old the tele-extender is. Could that be the problem?
Any help appreciated.

Also, this is my first post here on BPN!!!
Jay

[van bogaert erik]

I borrowed a canon 1.4 tele-extender to go with my canon 50 D and canon 400 mm L . The lens alone autofocuses great. When I attach the tele-extender, it does not autofocus on still or moving images - no auto focus at all. Used sport, Tv and Auto modes. Still no autofocus.

Don't know how old the tele-extender is. Could that be the problem?
Any help appreciated.

Also, this is my first post here on BPN!!!
Jay

Is this the 400mm f5.6 lens ? The canon 50D doesn't autofocus when you having f8 (400mm f5.6 + 1,4 extender)

[Jay Mlazgar]

It is the 400mm f5.6. Just out of curiosity, would a 7d autofucus with this combination?
Thanks!
Jay

[Roger Clark]

It is the 400mm f5.6. Just out of curiosity, would a 7d autofucus with this combination?
Thanks!
Jay

Hi Jay,
Only 1D series will autofocus at f/8. The 7D will not.

Roger

[Hayath Mohammed]

You could try taping the pins on the tc..will affect af speed but should allow it

[David Stephens]

Canon has promised that the 5D MkIII will AF at f/8 after the next firmware update is available.