RE: [APML] Hutech IDAS LPS Filter Question

[Jerry Lodriguss <lists3@astropix.com>]

A couple of more notes...

The results you get using CC filters will depend on a couple of things.

If you use a cyan filter to cut out the red sky light pollution for things 
like wide field constellation shots, it will work fine.  On the other hand, 
if you hope to record, say, large red nebulae like the North American / 
Gamma Cygnii region in such a wide field shot, remember that the cyan will 
filter out some of the red in these nebula too. If you have green light 
pollution, a magenta filter will help and not hurt the red emission nebula.

These filters, while much less expensive than the IDAS filters, of course, 
don't really work as well either, but they will help somewhat.

There really is no substitute for a dark sky if you really want to capture 
faint stuff, and an IDAS filter will even help under the darkest sky with 
natural sky glow.

It might be hard to find a Cyan glass filter, you may have to use a Kodak 
Wratten Gel filter. They are optical quality, but not as durable as glass.

Your other option is to just shoot without a filter, and then color correct 
the image in Photoshop or another image manipulation program.

Jerry



>If you have mostly sodium vapor light pollution (red sky background at 
>night), you can try using a simple Cyan CC filter.
>
>If you have mostly mercury vapor light pollution (green sky background at 
>night), you can try using a simple Magenta filter.





Photoshop for Astrophotographers
http://www.astropix.com/PFA/PFA.HTM










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