Possible problem with 1.4x extender and 300 f/2.8 lens?

When I tried out my new Canon 300 f/2.8 lens today along with a 1.4xII extender I encountered a slight problem. I'd be using it and occaisionly either the IS would jump violently or communication between lens & camera would die and I'd either get a 00 reading where the AV reading was or I'd get an error message (I forget what that was!). This also happened when I tried the lens out stacked with both the 1.4x & the 2x. With the 2x on its own there's no such problems. Also I'd previously been using the 1.4x with my old 300 f/4 lens with no such problems?

Any ideas?

Thanks.

sounds like it wasnt quite on there right? they certainly are compatable.

Sounds like you may possibly have dirty contacts on either the lens, camera, or one or both teleconverters. Clean the electrical contacts off and try again.

Billginthekeys wrote in post #2119427
sounds like it wasnt quite on there right? they certainly are compatable.

Surely once it's fitted it's on properly, I doubt it can be not quite on? Maybe I should clean the contacts? Can I use something like Eclipse cleaning fluid for that??

Tom W wrote in post #2119483
Sounds like you may possibly have dirty contacts on either the lens, camera, or one or both teleconverters. Clean the electrical contacts off and try again.

You beat me too it I shall give them a clean and see how it goes. Thanks!

paulhillion wrote in post #2119497
You beat me too it I shall give them a clean and see how it goes. Thanks!

Eraser!
Use an eraser to clean the contacts.
(One without graphite all over it)

Choderboy wrote in post #2119516
Eraser!
Use an eraser to clean the contacts.
(One without graphite all over it)

And don't let the eraser crumbs fall into the lens. Possibly some electric contact cleaner sprayed on a soft cleaning cloth, lens tissue, or paper towel might work also. Don't spray it directly on the lens as it will soil the glass.