2x Teleconverter samples - Got any?

Anyone have experience with the 2x converted with a 300mm F/2.8 (either IS or non... I have the non), or 70-200 F/2.8 IS?

I have the 1.4x and the image quality still seems very good with it. I'm considering the 2x, but thought I'd see the opinion of others on this forum.

Thanks!

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Fawad
http://www.FawadKhanPhotography.com