I'm trying to decide between the Nikon 1.4x and the Kenko 1.4x. I'm able to find solid reviews on both, but I'm hoping someone(s) has/have had the opportunity to compare them. The Nikon, as usual, is nearly twice the money, but if there really is a difference, this is a long term investment and I'll do what I need to. In the short term would use it with my 80-200mm f/2.8, though intend to sell that to get the 70-200mm f/2.8 VR version. Long term I'm hoping to get the 400mm f/2.8 VR and would use the TC with that as well. I might try to use it with my 200-500mm, but that would have to be real good light. I usually shoot that lens are f/8 and in decent light the AF is reasonable quick; would like have to shoot it wide open, or go with a higher ISO - but less of a concern with this lens. My impression is that the Kenko will work with more lenses than will the Nikon, but the Nikon reviews tend to be a dash more glowing than those for the Kenko.