Sigma 120-300 f2.8, Canon or Nikon mount

Does anyone own this lens ?  DXO rates this right near the top of the telephoto zoom list…..better than any Nikon or Canon telezoom.

http://www.sigmaphoto.com/product/120-3 ... g-os-hsm-s

I did own it for a short period (sport version). It is sharp as a bare lens but only in the center, corners are not so great. My biggest qualm was with the focusing, firstly it needed adjustment with the USB dock at various focal lengths, with and without TC... great feature but a pain in the butt to do properly. Secondly it was simply not consistent at locking. I could take a burst of 12 shots with either a 5DIII or 1D4 and all would be OOF... but each shot slight more in focus than the last. Next set of 12 would all be sharp. Quite odd. It would also hunt for no reason in great light and not with a TC attached.

Sigma lenses are nice and sharp but I seriously hate their focus reliability.