Interesting. Nobody is using a Polarizer for contrast. I have the variable
polarizing for the moon but that is another story. I remember from my day
light photos using a Polarizing Filter that I can increase incredible the
contrast between the clouds and the sky.

The original idea I think was not to do better imaging on DSO, its to combat
the moon light. Could be used to filter moon light like it do with the sun
light?
I´ll try it.

Juan.
----- Original Message -----
Sent: Thursday, November 18, 2004 2:08 AM
Subject: RE: [M]: Use of Polarizers In Visual and CCD Astronomy


> The only thing I have ever used a polarizer for in astronomy is a variable
> polarizing filter for viewing the moon with a telescope, which is a rather
> specialized application. For that, I really like a polarizing filter.
>
> I cannot imagine using a polarizer for deep sky observing or photography,
> both because of the light loss (I don't even think that the light loss
from
> a good light pollution suppression filter is worth the light loss), and
> because you are not viewing bright, reflected light in deep sky objects.
>
> Mark de Regt
> Redmond, Washington, USA
> 47.7 N. Latitude; 122 West Longitude
> Astro Images: http://www.de-regt.com/Astronomy
>
>
> > -----Original Message-----
> > R. A. Greiner
> > Sent: Wednesday, November 17, 2004 5:52 PM
> > Subject: Re: [M]: Use of Polarizers In Visual and CCD Astronomy
> >
> >
> >
> > I have not seen any response as well.. I think the reason is that
> > there is
> > no point whatever to using a Polarizer for visual astronomy. Polarizers
> > always have some substantial light loss. The biggest fight in visual
> > astronomy is to gather light. As it is, even with large
> > telescopes, say one
> > meter and above, the light from many objects is so dim that they
> > can only be
> > seen by averted vision.
> >
> > I have never heard of anyone using polarizers. That perhaps the
> > reason for
> > no responses.
> >
> > Even in CCD astronomy you need all of the light you can possibly gather.
> > What would be the reason to through away some light? I can think of
none.
> >
> > Doc G
> >
> >
> >
> > ----- Original Message -----
> > Sent: Wednesday, November 17, 2004 5:46 PM
> > Subject: Re: [M]: Use of Polarizers In Visual and CCD Astronomy
> >
> >
> > > John,
> > >
> > > We are still waiting for any input.
> > >
> > > Bill Keicher
> > >
> > > At 09:10 AM 11/17/2004 -0400, you wrote:
> > >>What response did you get for your posting. Can you share them with
me.
> > >>
> > >>
> > >>John H Fraser
> > >>Cape Breton Astronomical Society
> > >>
> > >>
> > >>----- Original Message ----- From: "william mccarthy"
> > >>Sent: Wednesday, November 17, 2004 6:21 AM
> > >>Subject: Re: [M]: Use of Polarizers In Visual and CCD Astronomy
> > >>
> > >>
> > >>>Linear or circular?
> > >>>
> > >>>Bill
> > >>>
> > >>>
> > >>>
> > >>>At 01:21 16/11/2004, Bill Keicher wrote:
> > >>>>Polarizers are used in outdoor photography to increase color
> > saturation.
> > >>>>Polarizers can make the clear sky look deep blue by reducing
> > scattered
> > >>>>light that is polarized. The magnitude of this effect depends on
the
> > >>>>relative positions of the sun, the observer and the object observed.
> > >>>>
> > >>>>Has anyone used this technique to reduce the sky background
> > level caused
> > >>>>by scattered moon light or localized city light? Even though a
> > >>>>polarizer would reduce the light from an unpolarized source
> > by at least
> > >>>>half, It seems like using a polarizer would improve image
> > contrast under
> > >>>>certain otherwise unfavorable conditions. Seems like it
> > would be worth
> > >>>>trying.
> > >>>>
> > >>>>Clear skies!
> > >>>>
> > >>>>Bill Keicher
> > >>>
> > >>>
> > >>>
> > >>
> > >>
> > >
> > >
> > >
> >
> >
> >
>
>
>

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