Sorry as this seems to be a newbie question.

From what I have seen, there are two types of tele-converters. One like the T-Con17 which is affixed to the end of the lens. The other are the ones used in SLR/DSLRs which are attached in between the camera body and the lens.

So the question is what's the difference in quality/performance/usability between the two types? If there are not significant differences, other then non-SLR users are unable to use the 2nd type, then to a SLR user, why the preference for the 2nd type?

Thanks for answering.