Why is my M108 so red?

[Red meteor]

M108 captured March 20, 23 and 24.

L 20 x 300s

RGB 20 x 200s each filter

SW ED80 on pier-mounted EQ6. Guided with PHD2, cam ASI120MM, oag.

Processed in Pixinsight but not sure why there is such a red cast in the galaxy. Used background neutralisation and colour calibration. Increasing saturation just makes it more rosy.

I also had to crop more than normal due to rotation of the filter wheel when it started slipping on its screw thread.

I would be grateful for any suggestions re the colour or other advice.

Thanks, Graham

M108 LRGB.tif

[wimvb]

For colour calibration, you can create a preview containing only the galaxy, and use this as a white reference. Turn structure detection off. This is tge easiest way to achieve colour variation in a galaxy.

Later during processing, you have to make sure that (the peaks of) the histograms are aligned. This keeps the background neutral.

Hope this helps.

[alacant]

StarTools' interpretation. Any better? HTH.

[Red meteor]

On 02/05/2017 at 07:08, wimvb said:

For colour calibration, you can create a preview containing only the galaxy, and use this as a white reference. Turn structure detection off. This is tge easiest way to achieve colour variation in a galaxy.

Later during processing, you have to make sure that (the peaks of) the histograms are aligned. This keeps the background neutral.

Hope this helps.

Thank you for your suggestion. I have a couple of other galaxies ready for processing so I will see how they turn out and then experiment a little.

[Red meteor]

On 02/05/2017 at 13:28, alacant said:

StarTools' interpretation. Any better? HTH.

 

[Red meteor]

Thank you for spending you time. It is certainly less red, but I had expected the dust clouds to be almost black and they still look redish. Perhaps my expectation is wrong.

[alacant]

2 hours ago, Red meteor said:

my expectation is wrong

I think they are red... HTH.

[Red meteor]

On ‎02‎/‎05‎/‎2017 at 07:08, wimvb said:

For colour calibration, you can create a preview containing only the galaxy, and use this as a white reference. Turn structure detection off. This is tge easiest way to achieve colour variation in a galaxy.

Later during processing, you have to make sure that (the peaks of) the histograms are aligned. This keeps the background neutral.

Hope this helps.

I have now done as you suggest and it has made the difference. Thank you Wim.

[wimvb]

Really nice! (before I looked at it on my mobile phone, now I'm back at my computer, looking at the larger version).

I think that you can try deconvolution on this image. Deconvolution is a tricky process, but once you master it, it can really lift your images.

cheers,

[Red meteor]

Thanks Wim.

I have looked at deconvolution in "Inside Pixinsight" and it does look convoluted but will have to give it a try sometime.

I am pleased with the progress I have made in the last few years, but to move from 'very nice' to absolutely stunning like yours and others on SGL is quite a step. I find controlling the backgound noise a major problem and need to learn more about using masks before tackling deconvolution. I have just bought a used Baader 7nm Ha filter so more learning (and longer exposures) required.

It's all part of the fun!

Regards, Graham

[wimvb]

I have an article on my blog (wimvberlo.blogspot.se) on noise reduction in PixInsight. Warren Keller's use of MLT is also very useful, and quicker. That should get you started. I'm planning on doing a write up on deconvolution, which can be tricky to get working properly.

[Red meteor]

THanks again. I will have a look at your blog.