It is unfortunate that this is the first ever super telephoto I’ve used that actually was optically bad, really bad (bad sample, I have full confidence in the design).
Update May 1st! One reader wrote to say this:
Mine was awful, too. Far behind the 200/2 and 500/4, and even slightly behind the 300/4 when shooting both wide open! At f/4 it caught up with the 300/4. I didn't know what to make of it, so for now I returned it without getting another one. But it must be a bad sample. It's hard to believe those get out there with lenses of this price range.
A super telephoto should be very close to peak performance wide open. It is highly unusual to see poor performance (even off center) when wide open. Mouse over the image below to see f/2.8 vs f/4. This is not focus error, I must have shot 20 comparisons. Just a bad lens.
Regrettably, the optical problem ruined all my 1.4X and 2X teleconverter tests as well, so there will be some delay on that front. I might resort to using the 200mm f/2 VR instead, and heck maybe it deserves a review anyway.
Still, the results with the 300mm f/2.8G VR II are highly instructive as to what to look for when you obtain a new lens.