I am getting a Canon xsi for christmas with a 70 -300 mm lens. I called J&R whom we have used for several purchases for advice on other accessories. I asked about using an extender or teleconverter, and they recommended one. Then I called Canon and repeated the question to see if I got the same answer. I ended up talking to Tech support for lenses, and he said that I couldn't use an extender or teleconverter with that lens. He said the only lens you could use them on were the white barreled lenses.
Does this sound right to you????
Cross posted.
Gayla
Jackson, Mississippi
Canon S3 IS
Zone 7b; Heat Zone 9 (Ugh)