Good telephoto zoom with the Tamron mount advantage

There have been a lot of mid-level zoom-telephoto lenses out
there, and optically I think this is one of the better ones. It's
well made, with a solid feel, and I must especially salute the
macro function; I've obtained some wonderfully sharp closeups
with this user. A fixed-focal length telephoto is probably
appreciably sharper, especially by a major brand name like Nikon.
But among zooms this Tamron holds its own. And I can't say
enough positive things about the Adaptall mount system, which
allows me to use my Tamrons on both my Nikon and Pentax K-mount
systems, or just about any other manual camera brand I might turn
to. I've purchased two of these lenses, both used. One was
$125, in good shape; the other has a bad case of mildew damage on
the inner optics and cost much less, but I'm going to shoot with
it anyway and see if even the distressed Tamron optics give me
acceptable results.