In article <19970114221200.RAA09671@ladder01.news.aol.com>, diver1055@aol.com says...

>I would like to know if there are any downsides to using a 2X
>teleconvertor.

(This is probably the wrong group - maybe r.p.misc would be more appropriate...)
But, quickly, loss of sharpness at middle, and especially at wide
apertures, plus loss of two stops in lens speed....
Hope This Helps