According to bhup <nospam@hotmail.com>:

    Hmm ... with the D80, you can use the various AF lenses with no
problems -- but the manual focus, depending on whether they are AI or
not are:

with AI:    You can mount them, but metering will have to be
        separate, as the body will not meter through these
        lenses.

without AI:    You can't even mount the lenses on the D80 unless you
        get new AI aperture rings for them, or get the existing
        aperture rings modified to act as AI rings.

    If you consider the Nikon D200, you can meter through the AI
lenses as well -- but still will need to have the non-AI ones (if any)
modified before they can be mounted.
       
    But even if those last two lenses are non-AI, you still have a
good bit of Nikon glass which you *can* use easily.  *I*, at least,
would get a Nikon DSLR to use them.

    Note that your 16mm fisheye won't look like a fisheye on the D80
(or any digital Nikon made to date), because the 1.5 crop factor will
make it act more like a 24mm -- with some distortion, but not what you
would expect from a fisheye.  (I know, because I have a 16mm f3.5 AI
manual focus Nikkor which I occasionally use on my D70.  There is some
curving of straight lines -- but mostly it looks like a not too
corrected wide angle. :-)

    Of course, each of these will act longer than they do on a film
body for the same reason, so you probably will want the 18-70mm lens
which is provided as the kit lens on the D70 and the D200.  I'm not sure
what the D80 comes with -- but you *will* want something easy to use
with zoom to cover that range.  The 16mm fisheye will probably not be
satisfactory for that.

    Do you intend to shoot stereo with these with a new Pentax
digital body?  I'm not sure whether there *is* one which will do the
stereo.  If not -- why is it mentioned in this question in a DSLR
newsgroup?

    Good Luck,
        DoN.

You have a number of "top drawer" Nikon lenses already. It would take
some extra $ to repeat that with Pentax. Look at the Thom Hogan site
and his review of the D80. You may want to replace the 50 f1.8 with an
AF one, but that is only $120 new, you have the 60 macro anyway, one of
the"top drawer" lenses. If you want some speed lens that meters then
look at the 35 f2 Nikon or the 30 f1.4 Sigma.
The Pentax K10 is a nice looking camera, note doubt about it. But with
the AF Nikkor lenses you already have I'd go Nikon.

Tom

I am a long time Pentax user, but I would likely consider the Nikon
D200, considering the Nikkor glass you already have. I bought the *ist D
two years ago as I had 6 Pentax primes.

This is a hard decision, but the D200 is more camera but has AI/AI-S
compatibility, the D80 doesn't. The D200 and K10D both are weather
sealed. Tokina is rumoured to be the maker of Pentax's 10~17 fisheye
zoom. If not Tokina does have a similar lens;
<http://www.tokinalens.com/products/tokina/atx107afdx-a.html>

I feel the Pentax K10D is the camera the D80 could/should have been.
I'll likely buy the K10D based on I love how it feels and based on the
Pentax glass I own. My advice for you is the D200 is based on the great
Nikkor glass you own. The Pentax primes do get good money on eBay.