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Old 17-11-2008, 07:24 AM
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avandonk
avandonk

avandonk is offline
 
Join Date: Aug 2005
Location: Melbourne
Posts: 4,786
I have been doing 'natural' narrow band imaging for a while using HA and O3 filters. I assign the HA to RED. The O3 actually falls between the Bayer filters on a DSLR and exposes the blue and green pixels about equally. If you then assign the green to Green and blue to Blue you will produce the cyan colour of O3.

When monatomic Hydrogen atoms are stimulated by nearby stars they emit HA and Hb. The intensity of the Hb is about 0.30 of that of the HA. What we see on Earth is a different matter as the blue Hb is attenuated more than HA by any intervening interstellar dust and extinction in the Earths atmosphere. You can always produce a Hb signal by doing pixel maths on a HA image. That is multiply by 0.30 or less if you want to simulate extinction.

The next thing to do is to collect colour data to get the correct star colours.

Here are a couple of examples.

Just HA and O3.
http://www.iceinspace.com.au/forum/s...ad.php?t=37660

These are with HA O3 and colour and HDR to preserve dynamic range.

http://members.optusnet.com.au/~fmlee/lmchdr_col+nb.jpg

http://members.optusnet.com.au/~trlee8/col+ha+o3.jpg


I do have a Hutech filter that records all blue from Hb up. This is most useful in separating blue from O3 from that of blue due to Hb and blue reflection nebula.

I use ImagesPlus for combining the different colour images. It is essential that they have the same size and content for combination and I use RegiStar for this.

Bert

Last edited by avandonk; 18-11-2008 at 07:30 PM.
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