RE: [APML] Light pollution filters and Comet NEAT

["Dale Ireland" <direland@drdale.com>]

 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/filtplt.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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