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Lack of star color with HOO blend?

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#1 Henry from NZ

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Posted 12 July 2020 - 06:34 AM

Personally I found that with HOO blend the stars lack colour - they are mostly just white.

 

This differs from the SHO blend, where the stars have more varied colours -- of course, I realise that none of these colours are "real" in a narrowband image.

 

Short of taking RGB subs for star colours, is there some easier way to give the stars some colours with HOO blend?

 

 



#2 schmeah

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Posted 12 July 2020 - 09:15 AM

That’s interesting, because have always gotten far better and more natural star color with bicolor Ha/OIII processing than SHO. Have you tried to use Steve Cannistra method?
http://www.starrywon...chniquenew.html

 

Derek



#3 WebFoot

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Posted 12 July 2020 - 12:17 PM

1.  SII has a larger psf than OIII, all else being equal.

2.  OIII has a larger psf than Ha, all else being equal.

3.  So HOO will have more blue-green stars than a good RGB will have blue stars, and the color typically would be stronger.

4.  And SHO will have lots of red/magenta fringe on all or almost all of the stars.

 

In my experience, SHO and HOO both have colorful stars, but the colors are not "natural" colors.

 

Mark


Edited by WebFoot, 12 July 2020 - 12:52 PM.


#4 Stelios

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Posted 12 July 2020 - 02:26 PM

There's nothing that stops you from doing SHO for stars (use Starnet to separate stars), use HOO or HOS or whatever for the main image (again, use Starnet this time to *remove* the stars) and then add back the SHO stars to the starless HOO or HOS.



#5 Henry from NZ

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Posted 15 July 2020 - 07:00 AM

Thanks for the replies - Sorry I did not see them until now.

 

I do not know why I tend to get mostly white stars with HOO. My guess is that since G=O and B=O, if O is similar to H then you end up with R at a similar level to G=B which yield white stars?

 

I do not usually do HOO as I generally prefer the gold-cyan/blue motif of SHO. However for some targets S is rather weak and not worth collecting.

 

Thanks Derek I will go through the link and see how i can adapt it for Pixinsight....




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