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Mike,
It is hard to describe.
The only "scientific" objection I have is against
all kinds of semi-transparent mirrors, because
they decrease the amount of light necessary for
twilight observations.
Concerning the astigmatizers and the prisms,
this is just a matter of feeling, I cannot put it in words.

By the way, even celestaire advertisement (if I remember it correctly)
warns that you should try the astigmatisor first, it is not
to everyone's taste. I had some limited opportunity to try
recently (from the Cassens and Plath office windows only)
and I decided that I did not like any of their additions to
their Basic Model.

Alex.

On Mon, 8 Aug 2005, Mike Hannibal wrote:

> Hi Alexandre,
>
> my brain is addled - I meant Polaris. My apologies.
>
> I would be very happy if you would expnd further on
> your views about the "gimmicks".
>
> Thanks
>
> Mike
> --- Alexandre E Eremenko 
> wrote:
>
> > Dear Mike,
> > I've never heard of a C&P "Pelarus" sextant.
> > Maybe you mean C&P Polaris?
> > (A "star specialist" as they call it)
> >
> > I have a very limited experience with
> > C&P sextants (once Fred Hebard let me try his,
> > and recently I visited their factory where I had an
> > opportunity to try them all from the window of their
> > office).
> > And I have to say that NONE of their sextants
> > is my "dream sextant":-)
> > In particular I was disappointed with all
> > these gimmicks like astigmatizer,
> > Schueler prism, and fancy horizon glasses.
> >
> > I strongly prefer to have a variety of scopes
> > and eyepieces instead, an eyepiece filter
> > and a simple "traditional" horizon mirror,
> > which is most light-efficient of all of them.
> >
> > Alex.
> >
> > On Mon, 8 Aug 2005, Mike Hannibal wrote:
> >
> > > If you had a choice between a C&P Horizon Ultra
> > and a
> > > C&P Pelorus which would you choose? Money isn't
> > the
> > > issue.
> > >
> > > The use is the full breadth of uses to which you
> > might
> > > put a sextant with an equal balance between
> > > star/planet sights, sun sights and coastal nav
> > stuff -
> > > distance off, horizontal bearing etc.
> > >
> > > For those unfamiliar the key differences between
> > the
> > > two instruments are:
> > >
> > > 1) both use the same frame and "running gear";
> > >
> > > 2) the Horizon Ultra has a whole horizon mirror,
> > > polarisers in both sets of shade glasses and
> > > Schueler's double prism to get verticality right.
> > In
> > > other words it's a specialist sun machine;
> > >
> > > 3) the Pelorus has standard shades, an
> > astigmatiser
> > > for stars and planets, and an unusual horizon
> > mirror
> > > that is about 70% silvered in the a centre
> > vertical
> > > strip and unsilvered on either side. It is
> > designed to
> > > be very effective with dim stars but still OK
> > brighter
> > > objects.
> > >
> > > I guess my current thinking is that the polarisers
> > are
> > > nice and make sun brightness and horizon clarity
> > very
> > > easy to get just right but that the Polaris is
> > > proabably better for stars as it isn't hampered by
> > the
> > > known issues of a whole horizon mirror. On balance
> > > what I want is the Pelorus with the polarisers as
> > > well. I expect that verticality of the instrument
> > will
> > > not be an issue when using the astigmatiser but
> > that
> > > you'll just have to rock like you always do when
> > doing
> > > sun/moon.
> > >
> > > Love to hear your views, and particularly if
> > anyone
> > > has used the Polaris or the Horizon Ultra.
> > >
> > > Regards
> > >
> > > Pelorus
> > >
> > > Send instant messages to your online friends
> > http://au.messenger.yahoo.com
> > >
> >
>
>
> Send instant messages to your online friends http://au.messenger.yahoo.com
>

   

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