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Narrowband with Luminance

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#1 FloridaObserver

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Posted 19 March 2019 - 04:28 PM

Apologies in advance if this was covered before, but here goes.

 

I've been capturing narrowband images from my light polluted backyard (H alpha and Oiii), and am considering traveling to a dark site once a month for luminance.  My work schedule is pretty busy, so don't have much time to work on capturing RGB.  

 

Question for the group: Has anyone tried combining luminance with narrowband only, i.e. LHO imaging?  If so, I'd be interested in seeing any results, and if it's even worth attempting.

 

Thanks,

 

Doug



#2 avarakin

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Posted 19 March 2019 - 11:54 PM

I don't think this makes much sense. Narrowband filters allow you to "travel" to dark site without leaving home. You can take G or SII channel in order to have better colors  in case if it is your objective. I normally use H as luminance as it is normally the stongest signal. When I travel to dark site , I normally take L and then take RGB from home. 

 

Alex


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#3 FloridaObserver

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Posted 20 March 2019 - 06:22 AM

Thanks, Alex.  I am currently imaging narrowband from home.  I was looking for input on whether combining luminance (from a site with no light pollution) will give good results when blending with narrowband (from my backyard) instead of the typical RGB.



#4 Jon Rista

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Posted 20 March 2019 - 11:35 AM

Thanks, Alex.  I am currently imaging narrowband from home.  I was looking for input on whether combining luminance (from a site with no light pollution) will give good results when blending with narrowband (from my backyard) instead of the typical RGB.

I would not blend lum with NB. Luminance is full spectrum, from 390nm to 710nm, and will not support the high contrast details that narrow band filters support. Further, you may end up with some very strange coloration in the final image if you try to blend lum with NB, since lum represents over 300n, of wavelengths, whereas most narrow band emissions primarily represent just ONE wavelength. 

 

The benefit of narrow band imaging is primarily one of contrast. Higher SNR is a byproduct of potentially being able to expose longer each sub, but that is not necessarily guaranteed in a strict sense. The main benefit of narrow band is contrast, and combining lum with nb will nuke the contrast. 


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#5 BenKolt

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Posted 20 March 2019 - 11:46 AM

Apologies in advance if this was covered before, but here goes.

 

I've been capturing narrowband images from my light polluted backyard (H alpha and Oiii), and am considering traveling to a dark site once a month for luminance.  My work schedule is pretty busy, so don't have much time to work on capturing RGB.  

 

Question for the group: Has anyone tried combining luminance with narrowband only, i.e. LHO imaging?  If so, I'd be interested in seeing any results, and if it's even worth attempting.

 

Thanks,

 

Doug

Doug:

 

I also expect this to not work well for the reasons stated above, but nothing is lost by trying it out for yourself!  If you have some luminance and NB data of the same object, give it a go and see what happens.  I have heard of some people using the L data to help bring down the noise of NB channels, but I don' recall the prescription that was used.  I'm sure if I made a guess I'd mangle it up anyway, so I won't even try.  Anyway, if you get some interesting results, please post them.

 

Ben


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