Hi--

><< The lens is excellent at f11, but loses some contrast and corner
> performance (still good for a zoom...) at "wider" stops. A faster
> prime is much easier to focus accurately, and wide stops are often
> desireable for portraits. You can use it, but it is probably not
> an ideal lens for the job...

>When you say that it is great at F11, do you mean it's great at F11 compared
>to primes at F11 or just primes over all even at F5.6 or F8? Thanks

???
At stops wider than about f11, primes will easily beat this zoom.
At stops wider than about f4 (f3.5-5.6, depending on zoom FL...;-),
the faster primes are "infinitely" better...;-) Wider than about f11,
the performance differences between this zoom and most good primes
get greater as the stop gets wider. This is a good lens at f11, but
at f5.6 almost any good prime is better - and at f2.8 and wider,
there is "absolutely" no contest...;-)
I sold my 24-120, good as it was, since it is a very limited-use
lens when highest-quality performance is desired... Only a few
zooms nearly equal primes within their range at a wide range of
stops.