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Unable to get any nebulosity from Rosette

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#1 nmaletto

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Posted 28 February 2020 - 09:03 AM

I shot like 2 hours of 90 sec exposures and i can see the open cluster clearly, but exactly no nebulosity. I don't know if it is a light pollution issue not allowing proper contrast or something. I am using an achromatic 4 inch refractor and an ASI553.

#2 wrnchhead

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Posted 28 February 2020 - 09:10 AM

That's odd. I used 120 second exposures (mono) just in my urban back yard and the red channel had amazing nebulosity just in the preview window. What software and settings are you using to process? Do you have an example image? 



#3 nmaletto

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Posted 28 February 2020 - 09:12 AM

That's odd. I used 120 second exposures (mono) just in my urban back yard and the red channel had amazing nebulosity just in the preview window. What software and settings are you using to process? Do you have an example image?


Not to mention u captured nebulosity on orion just fine.... Im using photoshop and N.I.NA and deep sly stacker

#4 nmaletto

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Posted 28 February 2020 - 09:18 AM

this is a quick process. (i am aware the field isnt flat at all) i am just seeing no nebula at all. i even offset the frame to see the nebula more and nothing

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#5 bobharmony

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Posted 28 February 2020 - 09:19 AM

That is odd indeed.  I would think something would show in post processing with that amount of time.  I recently did three hours on the same subject with a DSLR and reflector - my result is here: https://www.cloudyni...a-in-monoceros/

 

I didn't see any of the nebulosity in the individual sub previews, but it appeared in the post processing.  More details of what processing you did with the image would be helpful.

 

Bob

 

 


Edited by bobharmony, 28 February 2020 - 09:20 AM.


#6 wrnchhead

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Posted 28 February 2020 - 09:22 AM

Well, that is possibly one of the least nebulous areas of it, though there is definitely some nebulosity present in that area. Is this your full field? Do you have a raw capture? 



#7 klaussius

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Posted 28 February 2020 - 09:24 AM

this is a quick process. (i am aware the field isnt flat at all) i am just seeing no nebula at all. i even offset the frame to see the nebula more and nothing

You've clipped the blacks significantly in that image.

Bear in mind that Rosette has relatively low surface brightness, at least compared to skyfog in heavy light pollution. Just how light polluted is your zone?

In mine, bortle 9, the nebulosity is there but buried under the noise. I need a decent stack to even start to see it, I don't know how much for a good SNR.

A rough calculation gives me 14.7/sqm surface brightness vs 17.6/sqm skyfog at my location. That means my S2F (signal to fog) is -2.9... visible, but barely,after accounting for skyfog noise.

Edited by klaussius, 28 February 2020 - 09:35 AM.

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#8 ngc7319_20

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Posted 28 February 2020 - 09:24 AM

I think you have the stacking parameters set wrong.  Can you post a raw frame?  It is like the black level is set very high.  You can see hints of red emission trying to peek above the black level near the middle of the frame.

 

post-322911-0-03736500-1582899430 x.jpg


Edited by ngc7319_20, 28 February 2020 - 09:34 AM.


#9 richorn

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Posted 28 February 2020 - 09:27 AM

I am currently shooting (mono) RGB stars on this target, and I am seeing very little nebulosity. I’m not sure how much you will get without Ha or OIII filters. Then again, I haven’t tried OSC on this target.

What filter are you using?

#10 nmaletto

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Posted 28 February 2020 - 09:32 AM

I think you have the stacking parameters set wrong.  Can you post a raw frame?

I just did everything recomended but here is the stacked image before anything

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#11 nmaletto

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Posted 28 February 2020 - 09:33 AM

I am currently shooting (mono) RGB stars on this target, and I am seeing very little nebulosity. I’m not sure how much you will get without Ha or OIII filters. Then again, I haven’t tried OSC on this target.

What filter are you using?

i do not yet own any filters, but these are the results i was able to get on orion last week

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#12 Tapio

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Posted 28 February 2020 - 09:35 AM

Yeah, Rosette is surprisingly faint nebula.
What's the f speed of the refractor?

#13 richorn

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Posted 28 February 2020 - 09:39 AM

Orion is a different beast, super bright.

It looks like you just need much much more integration time.

I’m shooting narrowband mono and my RGB framed are 120 seconds with almost no nebulosity. My Ha (and SII, OIII) are 500 seconds.

I’m not sure how that relates to OSC, but I would think you need longer and more subs.

#14 ngc7319_20

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Posted 28 February 2020 - 09:41 AM

Yeah Rosette is much fainter.  Your Orion image also has a high black level, but there most of the nebula is above the black level.  For Rosette, most of the nebula is below the black level.



#15 nmaletto

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Posted 28 February 2020 - 09:48 AM

Yeah Rosette is much fainter. Your Orion image also has a high black level, but there most of the nebula is above the black level. For Rosette, most of the nebula is below the black level.


Gotta be honest have no idea what black level is lol

#16 nmaletto

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Posted 28 February 2020 - 09:48 AM

Yeah, Rosette is surprisingly faint nebula.
What's the f speed of the refractor?


6.6

#17 richorn

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Posted 28 February 2020 - 09:52 AM

Gotta be honest have no idea what black level is lol


He is saying your background, the sky, is too dark. If you do that in software, you are hiding a lot of nebulosity. The sky should almost be gray...

#18 GoldSpider

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Posted 28 February 2020 - 10:06 AM

If you have a way to share your raw data, I bet a few of us could take a crack at processing it and make some more hands-on recommendations.



#19 nmaletto

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Posted 28 February 2020 - 10:08 AM

If you have a way to share your raw data, I bet a few of us could take a crack at processing it and make some more hands-on recommendations.


Any ideas on where to share it? Cuz i know it's way too much data for the forum lol

#20 terry59

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Posted 28 February 2020 - 10:09 AM

You have a wicked gradient and some other stuff as well from what I can see. How do your individual subs look?

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Edited by terry59, 28 February 2020 - 10:10 AM.


#21 nmaletto

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Posted 28 February 2020 - 10:11 AM

You have a wicked gradient and some other stuff as well from what I can see. How do your individual subs look?


I do backround subtraction in photoshop

#22 JoshUrban

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Posted 28 February 2020 - 10:20 AM

Just shot this object - err, aided my brother in shooting it.  I pointed the scope, he did the rest.  We were using an AstroTech 102ED refractor, a Canon DSLR, and an OIII filter which made ALL the difference.  It's much fainter than the Orion nebula, and vanished without the filter for us.  With the filter (Astronomik OIII), it showed right up on the preview screen with a 30 second exposure.  It's really big, though.  Is your shot too zoomed in?



#23 nmaletto

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Posted 28 February 2020 - 10:23 AM

Just shot this object - err, aided my brother in shooting it. I pointed the scope, he did the rest. We were using an AstroTech 102ED refractor, a Canon DSLR, and an OIII filter which made ALL the difference. It's much fainter than the Orion nebula, and vanished without the filter for us. With the filter (Astronomik OIII), it showed right up on the preview screen with a 30 second exposure. It's really big, though. Is your shot too zoomed in?


Yeah with my focal length and sensor size i cant get the whole thing

#24 GoldSpider

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Posted 28 February 2020 - 10:43 AM

Any ideas on where to share it? Cuz i know it's way too much data for the forum lol

 

Is Google Drive an option for you?



#25 ngc7319_20

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Posted 28 February 2020 - 10:59 AM

I do backround subtraction in photoshop

Mayb leave off the background subtraction step.  I think you are subtracting off most of the Rosette.




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