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[RCC] Messier 51 / Whirlpool Galaxy

Request for feedback Messier Objects Galaxy M51
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Mario Wunderlich avatar
Mario Wunderlich avatar
Hi all,

Please check out my photo of M51 and give me feedback to help me improve.

Whirlpool Galaxy / Messier 51 / NGC 5194 (Mario Wunderlich) - AstroBin

I took this photo over 2 consecutive clear nights (unheard of!), for a total of 8 hours: 4 hours of luminance, 3 hours of RGB, 1 hour of H-alpha. Please help me improve by pointing out any pitfalls in my imaging or processing.

Stacking and Processing were done in PixInsight. I stack manually instead of using the WeightedBatchPreprocessing script. Then, I use a combination of PCC, HistogramTransform, ABE, MLT serveral times (denoising, debluring/sharpening, bringing out detail, etc), HDRMT, NoiseXT, BlurXT, LocalHistogramEq, and I use masking for some steps. I perform these separately for Luminance, RGB, and Halpha masters. I combine all three using LRGBCombination and NBRGBCombination, then finally polish the image with LocalHistogramEq and/or DarkStructureEnhance script, and HDRMT if necessary.

I give my photo it's final touches in LuminarNeo, such as color toning, denoising a bit more, bringing out detail, and cropping.

Thanks for taking a look!

Best,
Mario
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andrea tasselli avatar
andrea tasselli avatar
Since you asked…

I would start over and keep to the very basics. In fact a simple STF of the RGB image to see what it is really there and what is artifact would help to guide further.
George Hatfield avatar
George Hatfield avatar
First, I would say that the galaxy is too blue, and the stars lack color.  The whole image is too contrasty. 

Suggestions for improvement.

1.  Why not use WBPP?  It is easy to master and saves a ton of time. 
2.  Use SPCC rather than PCC.  The former almost always gives a more accurate color correction.  If you have a problem getting a solution for the image coordinates, make sure the RA and DEC are right.  Then, make sure the FL and pixel size are correct.  I rarely have problems with the Image solver. 
3.  Use generalized hyperbolic stretch to convert the image to nonlinear.  There are numerous YouTube "how to" videos on this tool.  Most think it is the best way to stretch an image.  
4.  Use Starnet++ (or StarXterminator) to remove the stars so they can be stretched separately.  Start with a minimal arcsinh and then go to GHS.  Avoid over-brightening the stars so they retain color.
5.  I don't think there is any reason to use anything other than NoiseXterminator for noise reduction.
6.  I have found that this method of adding Ha is the easiest to master... Crazed Conceptions method (https://www.youtube.com/watch?v=LwuiS8N1A-E).  The tricky part is removing the red broad band from the Ha.  If the Ha turns black, you have subtracted too much.  Play with the amount to reduce the contaminating luminance of the Ha without getting too much clipping (black).  Add the Ha to the linear RGB early on... after gradient removal and before using SPCC.
7.  When adding the nonlinear luminance to the nonlinear RGBHa, try to get their mean (statistics) close.

Hope this helps.  

Here is mine (https://www.astrobin.com/pm8tmk/B/?nc=&nce=) with about 15 hours of total exposure.   Not perfect, but OK.
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Brian Puhl avatar
Brian Puhl avatar
Few things that stand out immediately.

Overuse of BlurX, sharpening and or deconvolution.      We like to use the term 'deep fried'.

Color accuracy (it's not even close).    You claim to have used PCC, if that's true, you manipulated the colors after correction.



Like Andrea said…   go back to a simple STF and see what you have.   I'd put money on that image looks far better than what you created here.

Galaxy images don't need alot of color manipulation.   Saturation increases are great, but individually curving colors will get you in trouble very quickly.   Don't try to create details you don't have. 

4 hours of RGB to 3 hours of luminance isn't much of a balance.   Your luminance probably did nothing for you.   A single hour of Ha on a galaxy that doesn't have a ton of Ha to start with, probably didn't help much.      Your time would have been better spent dumping it all into RGB, or devoting more time to luminance.
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Quinn Groessl avatar
Quinn Groessl avatar
Unlike others, I don't mind the colors of the galaxy itself. If anything, I'd say it's a little more purple than I would personally do. I'd have it more blue. You could boost the saturation on the stars a bit.

The big thing that pops out to me though is the sharpening. To me it's way over sharpened which I have a tendency to do too.  The background looks pretty good though, you didn't try and make it too dark.
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