Its sharp, the OS is top notch, heavy but it pulls the babes closer.
The TC that I have is the 2x tele. I should have gone for the 1.5x to be honest because the quality drops but on a sunny day its hard to see the loss.
Now, on the 1.5x and the 2x you loose the AF but the OS works, if a little less that usual. See, you are now at 800mm at the bottom end so the teleconverter reduces the OS to kinda half, but still works a treat. Now, the AF “does not work”. This is true but with a little mod you can get this all back. By taping off the 3 last pins of the tele you can get AF back, again, like the OS its not perfect but still worht the effort. I think you might have to get the Sigma branded tele.
K, sure get back to me if you have more questions.
SteveFE: Yeah, selling the 350D, breaking my heart :( But sure, must spoil myself for XMas cause no else will spoil me :( LOL! Must get back to Flickr soon and get a meet-up in stone. Happy snapping.