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Is there any advantage using NB in dark skies?

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#1 Ballyhoo

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Posted 24 May 2020 - 04:11 PM

Is not the purpose of NB from an amatuer standpoint, the mitigation of light-pollution?  In dark skies I would think it is all about LRGB. second point is, and this is being discussed but not really resolvoed, in dark skies, is there much of an advantage of MONO versus OSC?  If you are in dark skies, will you use mono or OSC? 



#2 sg6

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Posted 24 May 2020 - 04:24 PM

I have assumed that the purpose of NB is to collect just that part of the spectrum alone. As OIII and Hb are very close to show the 2 different spectra you would need to use the 2 equally narrow filters - then change the apparent color of one in the processing.

 

Even in Blue you have already OIII and Hb, in Red is Ha and SII at 656nm and 672nm respectively. A "red" filter would I expect pass both through and you are unable to differentiate.

 

I would say NB is to select only those wavelengths you specifically want to collect and build an image with or from. That they also can cut out the light pollution is secondary byproduct.

 

If the LP is from the classic sodium how with an NB do you image the Na wavelength without some light pollution getting through? In that instance NB would seem to fail to block light pollution.


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#3 kel123

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Posted 24 May 2020 - 04:28 PM

Is not the purpose of NB from an amatuer standpoint, the mitigation of light-pollution? In dark skies I would think it is all about LRGB. second point is, and this is being discussed but not really resolvoed, in dark skies, is there much of an advantage of MONO versus OSC? If you are in dark skies, will you use mono or OSC?


I think all your assumptions about narrowband narrowband and LGRB are incorrect. Narrowband and LGRB imaging mitigates light pollution but I don't know where you saw that the sole purpose of NB is because of light pollution.This is simply not true.

I don't know where you saw that the purpose of shooting in LRGB is because of light pollution and that imaging in mono vs OSC has not been resolved. It couldn't have been resolved better.
In simple terms, shooting in LGRB gives you the correct rendition of colors as you capture all the channels in each colour spectrum while OSC approximate the colors with the use of the inbuilt bayer matrix.

#4 Ballyhoo

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Posted 24 May 2020 - 04:36 PM

I think all your assumptions about narrowband narrowband and LGRB are incorrect. Narrowband and LGRB imaging mitigates light pollution but I don't know where you saw that the sole purpose of NB is because of light pollution.This is simply not true.

I don't know where you saw that the purpose of shooting in LRGB is because of light pollution and that imaging in mono vs OSC has not been resolved. It couldn't have been resolved better.
In simple terms, shooting in LGRB gives you the correct rendition of colors as you capture all the channels in each colour spectrum while OSC approximate the colors with the use of the inbuilt bayer matrix.

I understand I have made some simplistic assumptions in my OP. Please excuse me on that. So then I presume many of you are using mono for dark skies.  I realize again from the two above responses it is more complicated than my initial question implies.

 

notwithstanding i am suffering from growing pains using my mono in LRGB for flat calibration.   I am at the point that when going to darksite I might just want to shoot OSC for non NB targets and save my mono for urban imaging of NB targets.

 

For example, if you are imaging a target like M101 in a dark site  and you can use either a same branded OSC or its mono counterpart,  Is going through all the extra steps of mono imaging going to yield that much more than imaging with the OSC?  Are we just talking about a bit more efficiency, which could be mitigated using the OSC by padding with extra integration time?



#5 SilverLitz

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Posted 24 May 2020 - 04:40 PM

Depending on the target, NB can result in a better a much more pleasing image and clean up the composition.  NGC7000 (North America Nebula) is a very good example, as in LRGB the dense star field distract from the nebula, but in NB the nebula comes to the fore and the stars recede.

 

NB also allow MUCH more ability to increase hue contrasts.

 

Here is my NGC7000 in NB:

 

NA_SHO (LoRes).JPG


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#6 SilverLitz

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Posted 24 May 2020 - 04:44 PM

Compare it LRGB, with MUCH busier star field:

 

NA_RGB (LoRes).jpg



#7 kel123

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Posted 24 May 2020 - 04:49 PM

I understand I have made some simplistic assumptions in my OP. Please excuse me on that. So then I presume many of you are using mono for dark skies. I realize again from the two above responses it is more complicated than my initial question implies.

notwithstanding i am suffering from growing pains using my mono in LRGB for flat calibration. I am at the point that when going to darksite I might just want to shoot OSC for non NB targets and save my mono for urban imaging of NB targets.

For example, if you are imaging a target like M101 in a dark site and you can use either a same branded OSC or its mono counterpart, Is going through all the extra steps of mono imaging going to yield that much more than imaging with the OSC? Are we just talking about a bit more efficiency, which could be mitigated using the OSC by padding with extra integration time?


It all boils that to your own preferences. Shoot with the camera you are comfortable with and no one will begrudge for that.

You can produce excellent pictures, even in light pollution with with just light pollution filters. Those images may be good enough for you, atleast for now, especially when you are not trying to win a competition.

Don't bite more than you can chew.

#8 Ballyhoo

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Posted 24 May 2020 - 04:55 PM

well I really am struggling pre-proccing LRGB right now with my mono. NB mono  I do not seem to have a problem with though.



#9 kathyastro

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Posted 24 May 2020 - 04:59 PM

I frequently shoot HaLRGB.  M101 is a good example of that.  My LRGB image was okay, but lacked pizazz.  When I added Ha to it, it came alive with more detail and colour.

 

Even if your red filter allows Ha light to pass through, and your sensor responds to it, you are getting a broad mix of different reds that are indistinguishable from one pixel to the next.  When you add Ha, you are adding contrast between what is Ha and what is not Ha.

 

Whether or not it is worth the extra effort is up to you.  I find that the end result is well worth the modest amount of extra work.  But if you don't, then just leave out the Ha.  The reason we do this hobby is to feel good about what we do.


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#10 Ballyhoo

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Posted 24 May 2020 - 05:14 PM

I frequently shoot HaLRGB.  M101 is a good example of that.  My LRGB image was okay, but lacked pizazz.  When I added Ha to it, it came alive with more detail and colour.

 

Even if your red filter allows Ha light to pass through, and your sensor responds to it, you are getting a broad mix of different reds that are indistinguishable from one pixel to the next.  When you add Ha, you are adding contrast between what is Ha and what is not Ha.

 

Whether or not it is worth the extra effort is up to you.  I find that the end result is well worth the modest amount of extra work.  But if you don't, then just leave out the Ha.  The reason we do this hobby is to feel good about what we do.

 

Are there other targets you enjoy, well I am sure there are, maybe some target examples you enjoy LRGB, HA?



#11 kathyastro

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Posted 24 May 2020 - 05:26 PM

Are there other targets you enjoy, well I am sure there are, maybe some target examples you enjoy LRGB, HA?

Off the top of my head, M33 is a great one.  There are quite a few galaxies with Ha regions.  And of course, emission nebulae are all about Ha.


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#12 kel123

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Posted 24 May 2020 - 05:29 PM

I frequently shoot HaLRGB. M101 is a good example of that. My LRGB image was okay, but lacked pizazz. When I added Ha to it, it came alive with more detail and colour.

Even if your red filter allows Ha light to pass through, and your sensor responds to it, you are getting a broad mix of different reds that are indistinguishable from one pixel to the next. When you add Ha, you are adding contrast between what is Ha and what is not Ha.

Whether or not it is worth the extra effort is up to you. I find that the end result is well worth the modest amount of extra work. But if you don't, then just leave out the Ha. The reason we do this hobby is to feel good about what we do.


Can you please post your Astrobin link?

#13 17.5Dob

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Posted 24 May 2020 - 05:37 PM

I don't know where you saw  that imaging in mono vs OSC has not been resolved. It couldn't have been resolved better.
In simple terms, shooting in LGRB gives you the correct rendition of colors as you capture all the channels in each colour spectrum while OSC approximate the colors with the use of the inbuilt bayer matrix.

???

You will get the same colors shooting OSC as RGB. You are shooting through the same color filters in both. The only difference is that RGB is is more efficient at collecting the data.
 



#14 ks__observer

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Posted 24 May 2020 - 05:51 PM

You will get the same colors shooting OSC as RGB. You are shooting through the same color filters in both. The only difference is that RGB is is more efficient at collecting the data.
 

Not sure I would say RGB is more "efficient."

It two very different procedures.

Over a three hour capture:

OSC -- 3 hours of red, green, blue, but only 1red:2 green:1 blue matrix

RGB -- 1 hour of full sensor red, green, blue

 

A OSC pixel (3 hours of data) will have a much higher SNR than a RGB pixel (1 hour of data).

Given that a OSC is reduced resolution compared to a mono camera, you can bin the mono and get better SNR and probably still have maybe equal or better resolution than the OSC.

 

With that said, I have only ever shot with RGB.


Edited by ks__observer, 24 May 2020 - 05:52 PM.


#15 kathyastro

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Posted 24 May 2020 - 05:54 PM

Can you please post your Astrobin link?

Link is in my signature.



#16 ks__observer

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Posted 24 May 2020 - 05:55 PM

Is not the purpose of NB from an amatuer standpoint, the mitigation of light-pollution?  In dark skies I would think it is all about LRGB. 

The Hubble Space Telescope shoots in narrowband, so narrowband is useful anywhere for very high contrast pictures.

But, obviously, if you live under LP skies, save the NB for home.



#17 SilverLitz

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Posted 24 May 2020 - 06:02 PM

I have shot targets in RGB that looked much better using Ha as the Lum, such as the Elephant's Trunk.  In this target RGB w/ Ha as Lum looked as good as SHO, but with a different color palette. 


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#18 Ballyhoo

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Posted 24 May 2020 - 06:04 PM

???

You will get the same colors shooting OSC as RGB. You are shooting through the same color filters in both. The only difference is that RGB is is more efficient at collecting the data.
 

right, so if not doing NB, I would presume one can mitigate OSC by adding more integration time. But how much more integration time?



#19 Ron (Lubbock)

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Posted 24 May 2020 - 06:42 PM

I used to do some narrowband imaging from a red zone when I lived in Lubbock, TX.  If I was too busy with work to drive out to a dark site, red zone narrowband was better than nothing.

 

After about a year of messing with red zone narrowband, I realized that the H-alpha wasn't affected too badly, but the O-iii was almost getting wiped out by light pollution.  FWIW, I use (affordable) Orion 7 nm filters, not million dollar ultra-NB filters.

 

A picture is worth a thousand words, so here's the picture that told me I still needed a dark site for O-iii.  It's the Crescent nebula in HOO bicolor.  There should be a faint, but rather conspicuous bubble of O-iii in this object, but where is it?  There's not a trace of it.

 

get.jpg?insecure

 

On the other hand, here's some "pure H-alpha" taken from the same red zone back yard.  There would be no point in traveling to a dark site to image this object in H-alpha, in my opinion.

 

get.jpg?insecure



#20 kel123

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Posted 24 May 2020 - 07:28 PM

Link is in my signature.


Very well. Let me switch to desktop version. I hear you are the best here 😃

Thanks

#21 kel123

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Posted 24 May 2020 - 07:42 PM

Link is in my signature.


Wow! What an incredible album of images. You are indeed talented. I love your mercury transit image with just a simple equipment.

#22 kathyastro

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Posted 24 May 2020 - 07:45 PM

Wow! What an incredible album of images. You are indeed talented. I love your mercury transit image with just a simple equipment.

Thank you. :D

 

Very well. Let me switch to desktop version. I hear you are the best here

Thanks

Rather a large exaggeration, but thanks anyway.  There are many better than me.
 


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#23 rockstarbill

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Posted 24 May 2020 - 08:28 PM

There are lots of folks at places like Deep Sky West that shoot narrowband. The moon is there too, ya know. lol.gif


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#24 dan_hm

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Posted 25 May 2020 - 11:15 AM

A picture is worth a thousand words, so here's the picture that told me I still needed a dark site for O-iii.  It's the Crescent nebula in HOO bicolor.  There should be a faint, but rather conspicuous bubble of O-iii in this object, but where is it?  There's not a trace of it.

 

get.jpg?insecure

How much did you stretch your OIII? I'm not sure I agree you "need" dark skies to get OIII on this target. According to that page, you had 99 minutes of OIII. More would be desirable, but even with that I would think you could get some of the OIII behind the crescent, even if it might be noisy. 



#25 Ballyhoo

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Posted 25 May 2020 - 11:41 AM

How much did you stretch your OIII? I'm not sure I agree you "need" dark skies to get OIII on this target. According to that page, you had 99 minutes of OIII. More would be desirable, but even with that I would think you could get some of the OIII behind the crescent, even if it might be noisy. 

I think the point he is making about whether you need dark skies for OIII is worthy of debate.  somehow I think  I have seen really nice triband images from Tokio and I did not get the sense that the OIII was overly supressed.




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