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Separate NB images

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6 replies to this topic

#1 astrosatch

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Posted 09 July 2020 - 07:41 AM

Greetings!

 

Does anyone know if there is a site that has separate SHO channels of objects? I only seem to find final integrated images and would also like to see  individual stacks of Ha, OIII and SII of  objects to easier plan imaging and process them afterwards. It would be helpfull  to see if there is any light in particular filter to decide to image or not.

 

I'm planning to image M8. If anyone has any pictures I would be gratefull.

 

Clear sky,

Andrej


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#2 Astrola72

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Posted 09 July 2020 - 08:58 AM

It's a bit tedious but I just search Astrobin, for my target, with a filter for minimum data=acquisition details. Then check the info on the images you like.

 

Joe



#3 astrosatch

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Posted 10 July 2020 - 03:31 AM

Thanks for reply. I always look acquisition details. It's hard to know what to do with channels. Ha ended very nice, but SII is poor. Should I increase sub length or just make more of them. I would increase sub length but I'm worried that stars would saturate more and destroy color balance.

#4 RJF-Astro

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Posted 10 July 2020 - 04:41 AM

More integration time means better signal to noise ratio. It does not alter the balance per se, it's just that you get more noise with less time and it is more difficult to stretch a channel. So getting more subs will help. Longer subs maybe, but it depends on factors, such as read noise, bandwith, light pollution and temperature.

 

In processing for me the biggest challange is to make the most out of Ha luminosity, while getting rid of the green color cast (according to taste). Also there are many ways to process SHO, it can be wortwhile to try a few and see which one you like best.



#5 Dave53N

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Posted 12 July 2020 - 11:32 AM

Hi Andrej

 

One site that has separate NB images is Bill Snyder's website ( http://billsnyderastrophotography.com/ ).

 

Dave


Edited by Dave53N, 12 July 2020 - 11:33 AM.

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#6 astrosatch

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Posted 13 July 2020 - 09:25 AM

Thank you Dave. I'll look into it.

Edited by astrosatch, 13 July 2020 - 09:32 AM.


#7 WebFoot

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Posted 13 July 2020 - 03:51 PM

I think it's very much a matter of personal preference, and a question of how much time you're willing/able to devote to one target.

I rarely take SII images; only when I've seen an SHO version of something that I find attractive.  I sometimes will take only Ha and OIII, when I don't think an SHO would be interesting, but I know it has strong OIII emissions (so an HOO might be nice, and/or enhancing the RGB with Ha and OIII will be nice).

And sometimes I'll take all three sets of NB images, and process the data in different ways.
See, e.g., 

http://de-regt.com/A...GC7380.RCOS.htm

and

http://de-regt.com/A...GC6888.RCOS.htm

 

In my experience, most bright emission nebulae have a significant amount of Ha (obviously) and OIII, and most have enough SII that one can make a pretty SHO photo if desired (but, in the interest of full and fair disclosure, most pretty SHO images have done two things that might not be obvious:  (i) applied HLVG/SCNR to turn the green--the dominant color on most SHO images when realistically balanced, since Ha is the dominant emission--to a tan, and (ii) boosted SII and OIII so they make a colorful image, instead of one dominated by Ha.

There are lots of SHO images of M8 on the Web.

 

You'll figure out what pleases you (which, IMO, should be any imager's  primary goal) with some experience.

 

Mark


Edited by WebFoot, 13 July 2020 - 05:41 PM.



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