I bought this converter and used it with my D700 and 70-200 2.8 vrii. I was
very unhappy with the image quality it produced. I ran the combo through
many tests and this combination failed. The loss of sharpness was so
dramatic that I did not think any of the images were usable. The auto focus
had to hunt often and the 3D tracking was limited with this combination. I
checked it through all f/stops and the sharpness was still poor even when
shot from a tripod with cable relase. I actually tested two of these and the
results were varied...but both were very bad. Eventually I tested this lens
with the TC-17eii and was much more happy. The images were drastically
better. Without going into details of the specific tests I ran all I can say
is that in my opinion this teleconverter is for fast long prime lenses. The
70-200mm vrii works much better with the TC-17eii and TC-14eii. Skip the TC
-20 if you ar eusing it with the 70-200mm.