Dec 8 2005: The Tamron "F" 1.4xTC is quite a popular item as it renders generally good IQ, is relatively low-priced, and allows for AF on more setups than the more expensive TCs. But head-to-head, how does it fare against the well-respected Kenko "Pro 300" (white version, out of production)? I own both TCs and put them against one another here.
As of note, in terms of AF speed, both are about the same on the 100-400IS (Kenko taped). Without taping the 11-pinned Kenko, the 100-400IS matched with a 20D will NOT AF.