NGC 281 The Pacman Nebula

[MartinB]

I've imaged this a few times in the past and was interested to see how my ASI294 MM camera performed compared with my old QSI 530 using a SW MN190 scope.  Data was gathered in Sept and it has taken me some time to get round to doing a "proper" process.  I have had a look at Jon Rista's PI noise reduction articles https://jonrista.com/the-astrophotographers-guide/pixinsights/effective-noise-reduction-part-1/ He takes a different approach to using TGV denoise and MLT compared with others such as Adam Block.  I was quite pleased with the results although there is a bit of trial and error involved.

This is an HST image with 4 hours per channel in 10 min subs.  The moon was fairly prominent and I think this impacted on the data somewhat.

Camera: ASI 294 MM

Scope: SW MakNewt 190

Filters: Chroma 5nm 

Processed initially in PI and final tweaks in PS

[tooth_dr]

A very fine image Martin. 

[Tim]

Very nice Martin, has a soft, otherworldy feel to it

[vineyard]

That's v nice - particularly the delicate tendril structure of the big central Bok column.👍🏾

[TakMan]

Very nice image Martin. Lovely flat background and rich, yet unforced colour and details.

Without sounding nitpicking, can I ask if your data suffered from halos (I would think unlikely with Chroma filters), or is the 'smooth halo' around the bigger stars (see attachment) an artefact from using StarNet or something..? I think I've seen this before and perhaps some posts on how to add back the 'grain'.... there might even be something over on CN where someone was asking Russell Croman if he could add the 'noise' back in with his own star removal plugin...?

Just asking really. Season's Greetings and Clear skies...

Damian

[MartinB]

Thanks everyone 👍

11 hours ago, TakMan said:

Without sounding nitpicking, can I ask if your data suffered from halos (I would think unlikely with Chroma filters), or is the 'smooth halo' around the bigger stars (see attachment) an artefact from using StarNet or something..? I think I've seen this before and perhaps some posts on how to add back the 'grain'.... there might even be something over on CN where someone was asking Russell Croman if he could add the 'noise' back in with his own star removal plugin...?

Well spotted Damian, I hadn't even noticed!  I used Russ Croman's StarXterminator (brilliant!) and am familiar with the very helpful thread on CN.  I will have a look and report back!

[scotty38]

Great image Martin and usefully I am going to take a look at your denoise link. I did try TGV and MLT on my IC1396 images but without resorting to the manual I couldn't figure it out, well at least other than just "clicking buttons".

I have found that using ABE and DBE give me different results and that may be obvious but what I mean is that ABE looks better as a first pass but seems to be much noisier than DBE. The issue with DBE is that I am not 100% I am putting the points in the right place therefore if I can denoise ABE better I may be on to a winner 🙂

[teoria_del_big_bang]

A lovely image Martin, nice subtle colours and plenty of the dark nebulosity showing up 🙂 

Steve

[teoria_del_big_bang]

4 hours ago, scotty38 said:

I have found that using ABE and DBE give me different results and that may be obvious but what I mean is that ABE looks better as a first pass but seems to be much noisier than DBE. The issue with DBE is that I am not 100% I am putting the points in the right place therefore if I can denoise ABE better I may be on to a winner 🙂

I know what you mean and during the cloudy periods (basically 2021 for me 🙂 ) I have been doing a lot of practicing with PI and in particularly DBE as this is a major tool in the PI#s huge tool box.

I have really found that in a way where you place the crosses is not actually that important, for normal background extraction anyway. Of course don't place them very close to very bright stars or on the brighter bits of the nebulae but you do not have to miss all nebulosity by any means. The important thing is to cover all areas where you think there are some true background, even if there is dome feint nebulosity over it. Then play about with the main parameters, depending on what you set these to it will ignore the nebulosity and stars, you can play with the parameters (mainly Tolerance, shadows relaxation and smoothing factor)  and see what the results are and keep changing them till you are happy. Difficult to explain what and how much to change as really depends on trype of image and amount of nebulosity and real background is in the FOV.
I am starting to do my own documentation on the tools in PI I use most as I find this a good way of learning and also gives me a quick way of remembering what to do after periods of inaction, I have attached the DBE one. Please be careful it really was only for my own memory aids and is in words I understand and I must confess may not be 100% correct as it is really my understanding of the tool. It is also WIP and very much not yet finished by a long way. If it is of no help then please ignore it but I hope it may help a little at least.

Steve

 

DynamicBackgroundExtraction (DBE).docx DynamicBackgroundExtraction (DBE).pdf

Edited December 7, 2021 by teoria_del_big_bang

[scotty38]

Brilliant thanks I will have a look at that later. Nice one!

[MartinB]

Thanks Steve.

@TakMan I've had a look at the CN thread and it seems that Russ has resolved the issue.  Also Chris White has provided  a neat PI routine to eliminate although this is redundant now.  I think I'm processed out with this image.  I've done some crude clone stamping around the more prominent halos and can only really see the smoothing artefact when I go above 100% so I'll stick with this.  It's great that you can just keep updating the software without any further charge and the AI feature seems very powerful.

[Stuf1978]

Just lovely, great work  

[MartinB]

Thanks "Stuf"

[Sunshine]

Beautiful!

[assouptro]

I love this! 
it looks so natural and detailed, Fantastic colours! Processed with finesse! 

thank you for sharing 

Bryan

[MartinB]

Thanks Sunshine and Bryan.