In article <1995Aug29.123211@omega.ntu.ac.sg>, be7170013@omega.ntu.ac.sg says...
>Have seen Vivitar supe-wide zoom 17-28mm f/4.0-f/4.5 at a low price. Does
>anybody has experience or used this lens. How's the distortion and >sharpness like and is it worth a try.
>The Vivitar 19mm f/3.8 is another interesting super-wide. How's the >perfermance like.

I am a picky user, so keep that in mind when reading the following:
The 17-28mm Vivitar I tried was not up to professional standards,
but if you are low on cash and not too critical of soft edges and
corners, you can learn some things from using this lens. (I learned
that, wide-angle nut that I am, I do not like wide-angle zooms.)
Good (not even great) fixed focal-length super-wides are difficult
to design and manufacture, so it is amazing that this zoom lens
exists for the price, and that it is not worse than it is.
(As to the 19mm, I have only seen a couple of reproductions of
images taken with it, and based on those, I would make the same
comments about it that I made about the 17-28mm.)
Hope this helps