Try a tc-14e, I believe it will stil auto focus for you. But the tamron, and sigma converters will not work. I already tested them in the store with my 80-200 /2.8 lens.
If your 80-200 is AF-S then yes the 14e will work, otherwise, like I said, gotta get the 14b and stick with manual focus. Not sure what else is out there third party though, I don't think anything.
Use the Tamron Pro (actually a Promaster Pro 300) and auto focus works on my 80-400 Tokina mounted on my D50. I've haven't noticed any dark corners and I was amazed how sharp the pictures where at wide open zoomed to the max(1200mm). Haven't tried it on any of my other lenese yet. Sop far I am very pleased with mine.
