In article <32150FC0.37D8@lursoft.bkc.lv>, egons@lursoft.bkc.lv says...

>I wonder if anyone has any experience with Vivitar
>series 1 zoom lenses like 28-105 and 100-500.
>How good they are? Comments welcome.

I tried two Series I 100-500's. The performance was
distinctly on the, uh, not very good side. I tried a
28-90 or 28-105 Series I (can't remember which), but
I do remember the considerable illumination and
sharpness roll-off toward the corners - a decent
(but definitely not very good) lens, if bought cheap.
The 70-210 Series I's tend to be noticeably better
(very good), and the 90 macro is better yet (though
it suffers from a serious flare problem).
Hope This Helps