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Ultra-HDR - Ring Nebula with outer whisps in 20" scope

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#1 Bart Declercq

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Posted 03 March 2021 - 04:41 AM

In the past week, I collected almost four hours of H-alpha on the ring nebula (M57) which managed to get the outer whispy layers of this planetary nebula quite well. But the difference in brightness with the typical ring is quite extreme, there's no real way of making both visible in a single image without treating the bright and faint parts very differently.

I feel that I've managed to get this done quite nicely in this shot, which shows the typical "ring" aspect quite well but still manages to also clearly show those outer whisps - taken through a 20" F/4 Newton reduced to F/3 with an ASI2600MM camera - check out the full resolution image on Flickr:

 

50997027803_8cbde6a23c_b.jpg


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#2 litesong

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Posted 03 March 2021 - 07:03 AM

I love your image. You even got the 15Magnitude galaxy near by! & look at all those double stars....cool. M57 really is close to the Milky Way centerline.

The only thing that would make it better is if you made a black&white negative!


Edited by litesong, 03 March 2021 - 07:13 AM.

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#3 lucam

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Posted 03 March 2021 - 08:04 AM

Very nice, Bart! The ring structure around M57 is quite intricate and extended and you brought it out quite well.


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#4 Hobby Astronomer

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Posted 03 March 2021 - 09:52 AM

Yes that is Ultra HDR.

 

Can I asked how your processed it?

 

HA


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#5 Bart Declercq

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Posted 03 March 2021 - 10:04 AM

Yes that is Ultra HDR.

 

Can I asked how your processed it?

 

HA

Ridiculously simply actually - I saved a DDP-stretched version and an unstretched version in AstroPixelProcessor - in the unstretched version I separated out only the ring itself (with a bit around it) with a feathered selection. I put it on top of the DDP-stretched version, then played with the gamma of both pictures until the borders disappeared. It's a lot easier to do than in things like the Orion nebula which have a more complex structure.

One disadvantage perhaps is that the stars in the central "eye" of the Ring are very different in brightness from the rest of the image (to the point of being almost invisible here,) but that's inevitable as the inner nebula of the ring is still much, much brighter than the outer halo.




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