I will have to try it with my 70-200mm and see what happens. If it doesn't perform well with it maybe it is the brand and maybe Santa will be good and put a Nikon TC under the Christmas tree for me this year.
I have a Tamron 1.4 TC and have used it with my Nikon 500mm lens but it seems to always make the photos soft. However, wouldn't using a 1.4 TC give you about a 450mm range? Is there that big of a difference using the 300mm with the TC than using your 500mm lens?
Normally we don't get any of those here however, last year one showed up at the Falls of the Ohio and stayed on the side of the river that was furthest away so I was able to get any photos. Great shots!
Andy and I checked out the Nationals Bench Rest shoot last week. Some of the best shooters from around the world were there. Andy would like to compete next year. We will see. I kept myself busy taking photos.