I used to have the older Tamron 70-200mm which had poor focus but not bad sharpness, changed it over for the Nikon 70-200mm VR2 and never looked back, the Nikon will be the best 70-200mm out there to get, and in my case needing to use converters alot the Nikon version works amazing well with them, not sure if the Tamron can take any other than the Kenko? So if you want the best get the Nikon 70-200mm in my opinion...