Hi--

>Thanks very much for your response and yes, I had already seen your
>interesting web page which I had printed out. That is one reason I bought
>the lens ) I think I must have a faulty specimen and I'm going to send it
>back and get another one. I don't suppose there is more than one version of
>the f2.8 one is there? I have the AF one.

Optically there is only one version, but it is offered in both AF and
the nicer metal-barreled MF version...

>Comparing it to my poor Sigma 18 - 35 AF, the sigma has good coverage to the
>corner but gets nowhere near as good as the Nikkor 20mm in central 2/3 ds of
>the image (as you would expect) It seems though, from your web page
>comments, that Nikon may have decided to let the corners look after
>themselves until about f8, in order to get the main area quality up a bit.

In common with most Nikkor wides 28mm and shorter, central performance
is good wide open, but the edges/corners pop up around f5.6. I don't
recommend using these lenses wider than f5.6 (but since the FL's are
short, they can be used at slow shutter speeds to compensate...), and
they are quite good over the whole area by f5.6...

>Seems a pity that they can't achieve prime lens quality to the corners where
>Sigma almost do on a Zoom - well not really I suppose )
"Spencer Childs"

Well, they do, actually...;-) Just after f5.6, which is OK with
useable hand-holdable speeds of 1/15th and slower...