Dino - I omitted to address your other query re the AF settings. I am not sure what camera you have, but I based my set up on the CAM 2000 settings (for my D2H) recommended at the following site:http://www.luminescentphoto.com/articles/CAM2000/cam2000.html . I am sure that the advice given would work well with the D200, for example, as well as give a good background on AF for sports events.
Dino - You may have seen comments that the 1.4X gives the best quality and the 2x the worst. The 1.7 sits comfortably between the two. I borrowed (from my brother) a 1.7x to use with my 70-200 on my D50 and was very impressed with the results. In my (humble) opinion the combination is great. This was shot, effectively, wide open at f4.8 - not ideal and against the advice that this combination works best when stopped down 2 stops. Nevertheless, I have been very happy with this. This was shot at about 25m and is a 50% crop from the D2H's 4MP. Overall, I am really delighted with the results. If you want to see some stopped down a little more, look at the British Superbikes gallery within the Motorsports. I can highly recommend the TC-17EII with the 70--200.
