In article <4udfpo$3foo@sat.ipp-garching.mpg.de>, pereira@milbe.biochem.mpg.de says...

>I wonder if anyone has any experience with the Vivitar 17-28/4-4.5 zoom.
>It is a manual focus wide zoom and the price is very nice, but... how
>good is it? Comments welcome.

Uh, better than a pop bottle bottom, worse than any decent lens...;-)
People's standards vary a lot - the non-critical user may like it, but
those of us into the best optics do not. If you just want images
from a WA zoom, and money is short, it might be worth its price.
Specifically, the center performance is not terrible (or wonderful),
and the edges are poor. It never gets good over the whole frame, even
well stopped-down.
Hope This Helps