Tulip Nebula (Sh2-101) SHO (Hubble) narrowband

[x6gas]

I managed to get three clear nights on Sh2-101, the Tulip Nebula in Cygnus.  This is a narrowband image in the Hubble palette and I was pleased to catch a bit of the curved shock front created by the microquasar Cygnus-X1 in the top centre.

I'm still trying to get back up to speed on processing after a long break and I am also [still] trying to learn Pixinsight…  I'd had trouble with calibration and in particular overcorrection of my flats but I now seem to have a workflow that delivers decent result (whether they are better than my usual process in AstroArt 5.0 I'm not sure!).

Anyway, this was interesting for me as I processed the calibrated data in both PS and PI.  I was following AmyAstro's YouTube tutorial for the latter and massively overdid the noise reduction which meant that the image had that characteristic shot-through-Vaseline look.  The PS version was a bit too noisy and I wasn't that keen on that either.  I was going to go back and redo the PI process (and I am sure I will) but I blended the two and this is the result which I like a lot better than either of the originals!

Kit - Mount: CEM40; Scope: Tak FSQ85; Camera: Atik 460ex; Filters: Astrodon; Guiding: Atik OAG, QHY5L II, PHD2

Data - 35 x 600s each of Ha, OIII, and SII for a total integration of 18 hours calibrated with Bias, Darks (which I never usually bother with), and Flats.

And since I tend to leave a bit too much green in my images for many, here's the version after HLVG:

 

Edited September 26, 2019 by x6gas

[Kinch]

Great job....I found the area quite hard to process. For me - the top image does not have too much green....I left more in mine 😄.

[x6gas]

Many thanks Kinch.

Following something like my old PS workflow I found that the data got noisy very quickly.  I'm not sure if that was something to do with using PI for the calibration and I will go back and reprocess the whole data set using my old workflow to see if there is a difference.  I think I can do a much better job on the PI version, though, if I'm less aggressive in the background noise reduction steps...

Thanks again, Ian

[MartinFransson]

That looks great! If I may be just a little bit picky (which I only am if the image is great to begin with 😉) I think it´s pushed just a bit too hard. I would have preferred a slightly darker image and maybe with the added bonus of less prominent stars. But I fully understand the urge to push it as far as possible since you have massive data to begin with.

[x6gas]

Thanks Martin.

Fair points, and I always welcome constructive criticism; it's the only way we improve.  I don't really like inky black backgrounds - especially on images of emission nebulae - but I think maybe you are right and I could have brought the contrast up a bit and the brightness down a bit... or do you think I've just overstretched the data?  I must admit that the workflow I followed in PI applied the pre-canned standard stretch to the data and I do think it was a tad more than I'd usually go.

I promise not to push out a million versions but is this reduction in stars and tweak to the contrast and brightness an improvement?  I'm still [re-]finding my feet in terms of processing...

[MartinB]

Great image.  Whenever I get to this situation I ask my wife!  After hours of processing it becomes very difficult to be objective.  Leave it alone now and have another look in a years time!

I like what you have done with the last rendition except I don't like the complete elimination of green.  I like the aesthetics of the gold and blue but green equates to hydrogen and it seems a pity to eliminate it all together.  

Regardless of whichever process choice this is a cracking image.

 

[x6gas]

<smashyandnicey>Wise words, mate!</smashyandnicey>

Thanks Martin - appreciate the comments especially since it was your primers that started me on the imaging journey!

I do know what you mean about the green... All this feedback is helpful and I'll take it in to consideration when I reprocess the data.

Thanks again, Ian

Edited September 26, 2019 by x6gas
no means know

[MartinFransson]

1 hour ago, x6gas said:

Thanks Martin.

Fair points, and I always welcome constructive criticism; it's the only way we improve.  I don't really like inky black backgrounds - especially on images of emission nebulae - but I think maybe you are right and I could have brought the contrast up a bit and the brightness down a bit... or do you think I've just overstretched the data?  I must admit that the workflow I followed in PI applied the pre-canned standard stretch to the data and I do think it was a tad more than I'd usually go.

I promise not to push out a million versions but is this reduction in stars and tweak to the contrast and brightness an improvement?  I'm still [re-]finding my feet in terms of processing...

 

No, please don´t go pitch black for the background! I really don´t like that either. I try to stay above 25,25,25 for RGB values. I think for me it is more of overstretching it or maybe you could just try some local contrast enhancement without touching the stars? For example a curves layer where you bring the dark nebulosity and the bright nebulosity closer together, without touching the darkest background or the brightest highlights... kind of hard to explain in text 🙂

[MartinFransson]

What I meant was something like this. Hope you don´t mind!

Of course this doesn´t look prefect since I only had the 8-bit data to use as an example, I just wanted to show the shape of the curve. You can see the two sampled points, where I altered the curve.

[souls33k3r]

You've absolutely smashed it mate. Great work. Like you never left

[x6gas]

2 hours ago, souls33k3r said:

You've absolutely smashed it mate. Great work. Like you never left

You're very kind mate.  Ain't true, but you're very kind.

I honestly can't believe how much I've forgotten about processing in Photoshop, but it is coming back... And then there's learning PI which at the moment is just following recipes without really knowing why or what you're doing but I am sure it'll make sense one day!

[souls33k3r]

31 minutes ago, x6gas said:

You're very kind mate.  Ain't true, but you're very kind.

I honestly can't believe how much I've forgotten about processing in Photoshop, but it is coming back... And then there's learning PI which at the moment is just following recipes without really knowing why or what you're doing but I am sure it'll make sense one day!

3 years and I'm still trying to make sense of things in PI I guess this is why I love PI so much. The more you play with it, the more comfortable you get mate. Plus, we're all here to help each other

[gorann]

Nice image! I like the colours. I just wonder if you could not enhance the details a bit more. There are some interesting pillars/nodules in your image, especially centrally and down to the left. Have you tried any high-pass filtering in PS or other sharpening routines in PS, or deconvolution in PI?

[x6gas]

Thanks Goran.

I did apply some gentle high pass sharpening in Photoshop but I didn't want to overcook it so it's interesting that you think I could have gone further.  I think when I reprocess the data I'll stretch it less and see if I can sharpen it more...  I used to have a number of PS techniques in my toolbox that I think would have helped with this image so I probably need to dust those off and relearn them.  There are also some 'actions' that I used to use regularly that I also didn't deploy here.  The OIII data is a bit soft but the Ha is good so I may also try making a false luminance and using that for the sharpening.

I'm finding the hardest thing to get back into is getting a feel for what the data is telling you about how to process it.  Something that Olly, and Sara, and Barry, and others do so well...

Thanks again, Ian