Quote Originally Posted by Ragsy View Post
...I have heard that a teleconverter will effect the quality of the shot, i have never used one, is it true??...
It depends on extent, and whether it is noticeable in the final image. It can be due to magnified lens defects/little other contribution of teleconverter (TC), or it can be
that the TC is really poor in quality or is not suited to the particular lens. I use a Σ50-500, sometimes with Σ 2XTC, with no noticeable effect due to the TC.

Quote Originally Posted by TimCz View Post
...As for extenders, you'll always lose a bit of image quality,... focus speed, and light of course by throwing one on. I use one occasionally with my 400, and it does slow the AF down slightly, but the IQ isnt too bad slightly stopped down, but the loss of light is the real killer.
Tim, I hilighted part of your post. The rest of the explanation is OK, but it would be a more helpful reply to expand on that statement as well.

Am.