I received a Nikon TC-20E III teleconverter a few days ago. I’ve not really been an advocate of 2x teleconverters, but this new design from Nikon contains aspherical elements (Nikon claims it is the first teleconverter with such a design) intended to drastically improve performance.
A 2x teleconverter is only intended for use on fast telephoto lenses. In fact, Nikon’s design prevents mounting any of their teleconverters on non-AFS lenses. Because the teleconverter robs you of light (in the case of the TC-20E III, two full stops), autofocus performance may degrade and viewfinder brightness will diminish. Given that, I only have a couple of lenses in my arsenal that would be a good match for the TC-20E III:
70-200mm f/2.8 AFS VRII (becomes a 140-400mm f/5.6 lens)
200mm f/2.0 AFS VR (becomes a 400mm f/4.0 lens)
I also have a few lenses that might work ok, depending on my need for fast autofocus:
300mm f/4.0 AFS (becomes 600mm f/8.0 lens)
200-400mm f/4.0 AFS VR (becomes a 400-800mm f/8.0 lens)
600mm f/4.0 AFS VR (becomes a 1200mm f/8.0 lens)
So far, I’ve briefly evaluated sharpness and AF ability with each of these lenses in a non-scientific manner.
The new 70-200VR is slightly shorter and fatter than the VRI, but doesn’t seem too big. In fact, I think it feels just right in the hand. The MF ring is smaller, and this feature, combined with a new A/M AF mode, means that you’ll be unlikely to accidentally engage MF during AF usage by bumping the MF ring. Gone are the AF activation buttons on the end of the lens barrel (I didn’t use those on my old VRI, anyway). The tripod foot is the same as the original, and can be replaced with an Arca-Swiss foot from RRS or Kirk— I was able to use my old foot on the new lens.