The Cygnus Wall

[AMcD]

A further attempt to process my 13.3 hours worth of data on the Cygnus Wall acquired with a QHY8 with Optolong L-Extreme filter on a TS152 achromat mounted on a G11   Any criticism much appreciated as keen to get better...

[carastro]

Looks like some good data there, but also looks like too much noise reduction.

Carole  

[AMcD]

Many thanks Carole.  I am trying to absorb the mantra "less is more"!  The skies are not bad here tonight so am acquiring some more data and will have another crack at it over the weekend.  Many thanks again.

[Ouroboros]

Your picture has a lot of impact though, @AMcD. It has a 3D feel to it. I like it. 

[AMcD]

5 minutes ago, Ouroboros said:

Your picture has a lot of impact though, @AMcD. It has a 3D feel to it. I like it. 

Many thanks @Ouroboros.  I am still in awe of the fact that it is possible to capture these views of the Universe from the back garden!

[Padraic M]

3 minutes ago, AMcD said:

I am still in awe of the fact that it is possible to capture these views of the Universe from the back garden!

Agreed! And the same views from every back garden in this part of the northern hemisphere! It's mind-boggling, if only more people looked up.

btw I love your avatar, it looks vaguely familiar....

[Ouroboros]

Yes. With picture quality that professional astronomers with the best kit of only a few years ago would be truly envious of. 

[assouptro]

Great image! 
is it possible the focus was just a tad off? The stars look a little soft or that could just be noise reduction like Carole suggested? 
 

Thanks for sharing 

Bryan

[AMcD]

6 hours ago, assouptro said:

Great image! 
is it possible the focus was just a tad off? The stars look a little soft or that could just be noise reduction like Carole suggested? 
 

Thanks for sharing 

Bryan

Many thanks Bryan.  I think it is the noise reduction.  The autofocus on SGPro appears to be working pretty well, and far better than the Bhatinov mask that I used up until recently.  Managed a further 2.5 hrs on this target in the wee small hours so will have another crack at it this weekend.

[steppenwolf]

Your image has great potential but I too think you have over-smoothed it while removing noise. If you have a layers based image processing program like PS or The Gimp, a good way of avoiding this is to produce a copy of the 'noisy' version, noise reduce the copy and then layer it on top of the original where you can then adjust its opacity in tiny increments until the noise just appears thus retaining the detail in the nebula itself.

[AMcD]

3 hours ago, steppenwolf said:

Your image has great potential but I too think you have over-smoothed it while removing noise. If you have a layers based image processing program like PS or The Gimp, a good way of avoiding this is to produce a copy of the 'noisy' version, noise reduce the copy and then layer it on top of the original where you can then adjust its opacity in tiny increments until the noise just appears thus retaining the detail in the nebula itself.

Many thanks @steppenwolf.  I have this morning added in the 2.5hrs of integrations I acquired last night and I have restacked the totality of the integrations to retain 95% of the data, resulting in a total time for the image of 19.9hrs.  On the advice of @carastro and yourself, I have stayed away from aggressive noise reduction and voila.  Hopefully this is travelling in the right direction...

NGC7000_DSS_LStack_19.9hrs_Final.tif

 

 

[Padraic M]

Now that is sooo much better! You're getting value for your 20 hours exposure time and there's a load of detail visible that was hidden in the first version.

However, to me it's just crying out for more contrast, and I think the data has it in it. It's just a little flat to my eyes. I took a look at the TIFF in Gimp and you can see in the histogram, that space to the left is wasted dynamic range.

One tiny adjustment to the black point makes a huge difference; just make sure you leave a little space to the left of the curve, otherwise you're losing some of the dark detail.

There may be more that you can pull out with a bit more time. There are a bunch of youtube videos explaining levels and curves adjustment, including @carastro's excellent tutorials on how to do this in Photoshop.

[AMcD]

4 hours ago, Padraic M said:

Now that is sooo much better! You're getting value for your 20 hours exposure time and there's a load of detail visible that was hidden in the first version.

However, to me it's just crying out for more contrast, and I think the data has it in it. It's just a little flat to my eyes. I took a look at the TIFF in Gimp and you can see in the histogram, that space to the left is wasted dynamic range.

 

Many thanks, @Padraic M for the detailed response.  Interestingly, in PS there does not appear to be as much unused dynamic range available when Levels is selected but I will seek to extract some more contrast.  Many thanks again for the valuable advice.,

[AMcD]

I think this is as far as I can push it.  Now that I am at nearly 20 hours of integrations, it would seem a shame not to have another go once I get to twenty-four.  I think then I really need to look to another target for the oncoming winter.  Many thanks again to @Padraic M, @steppenwolf and @carastro for all the exceptionally valuable advice.

NGC7000_DSS_LStack_19.9hrs_Final.tif

 

Edited September 18, 2021 by AMcD

[carastro]

Much better than the first process.  

Carole