I'm thinking of updating my stuff this year and I find the Sigma's 50-500 OS seems to be a good lens to update to.
The only thing that worries me is that the image quality reported to be dropping fast near the edge and corner on full-frame cameras.
It's a problem serious enough for me to decide with kind of camera to buy, or if it's needed to wait for D400 or 7D2.
So anybody is using or has used this lens on any full-frame cameras? Is it usable near the edge for "A.net quality"?
Thank you in advance for your replies.