Re: [APML] Light pollution filters and Comet NEAT

["joe" <jmize@svic.net>]

Now that would be interesting, a polarizing filter...joe  :)


"May You Go Among The Imperishable Stars"

Joe Mize:     jmize@svic.net 
StarFields Observatory   http://www.svic.net/jmize
Chiefland, FL    29:24'33.4"N    82:51'37.7"W
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----- Original Message ----- 
From: "Centaurus A" <centaurus_a@virgilio.it>
To: "'Discussion of Film Astrophotography'" <astro-photo@seds.org>
Sent: Thursday, May 20, 2004 10:44 AM
Subject: RE: [APML] Light pollution filters and Comet NEAT


> Hi Dale
> 
> Thanks for sharing. I wonder if a polarizing filtre would do the same
> job.
> 
> Regards,
> Nicola
> 
> > -----Original Message-----
> > From: astro-photo-bounces@seds.org 
> > [mailto:astro-photo-bounces@seds.org] On Behalf Of Dale Ireland
> > Sent: 20 May 2004 16:09
> > To: 'Discussion of Film Astrophotography'
> > Subject: RE: [APML] Light pollution filters and Comet NEAT
> > 
> > 
> >  I took some NEAT shots with and without the IDAS filter with 
> > a Nikon D70, Nikon 58mm NOCT f/1.2 lens, 2-3 minutes. I got 
> > more and better tail structure in both the ion and dust tails 
> > WITH the filter which allowed longer exposures but even 
> > exposures of the same length looked better with the filter. 
> > Of course the camera has its own spectral response so I can't 
> > say this translates exactly to film but it worked in my 
> > situation. Dale
> > 
> > -----Original Message-----
> > From: astro-photo-bounces@seds.org 
> > [mailto:astro-photo-bounces@seds.org] On > Behalf Of steve 
> > banbury
> > 
> > 
> > Hi Greg and Jeff:
> > 
> > The IDAS filter response is shown at: 
> > http://www.sciencecenter.net/hutech/tokai/filt> plt.htm
> > 
> > The 
> > only spectra I could find on the web for  
> > C/2001 Q4 was at: http://home.freeuk.com/m.gavin/encke.htm
> > 
> > I didn't try to to superimpose the 2 plots, but  I can see 
> > that some energy would be lost using the filter. It still 
> > seems like a coin flip as to whether the reduction of local 
> > light pollution would make this loss acceptable.  I'm 
> > suprised someone hasn't already been down this path before.
> > 
> > cheers--steve
> > Greg Hartke wrote:
> > 
> > >Hi, Jeff,
> > >
> > >I'm not so sure this is correct.
> > >
> > >The IDAS LPS filter is a very different animal than the usual light
> > >pollution filters. It has relatively narrow stopbands at the 
> > frequency 
> > >of selected spectral lines which appear in prevalent public 
> > lighting. 
> > >Because the cometary spectrum really is farily broadband, 
> > most of the 
> > >light from the comet will make it through. Of course there will be 
> > >attenuation but it would normally be expected to be 
> > significantly less 
> > >than that of the narrowband pollution sources.
> > >
> > >I would expect the IDAS LPS filter to be very much worth trying for
> > >this application.
> > >
> > >Greg Hartke
> > >Sykesville, MD
> > >
> > >  
> > 
> > 
> > 
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> > 
> 
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