How to make Whirlpool galaxy image better ?

Hi Mustafa,
I've got the same DSLR as you for a long time, and used it both in modded and un-modded configuration. It's a good camera and fits perfectly a 80mm refractor like your Orion 80ED, and can deliver decent images of cluster, nebula and galaxy. Taking 300s subs is also a good point, so long there is no big issue with unguided tracking. Heat noise during warm season could make processing harder. Now, my question is about how do you manage your stacked image under DSS. Before switching to Pix for a full preprocessing stage (calibrate, align and stack), I was using DSS to get a quick result and saved it "unmodified" in FITS format, means without any adjustments made directly in DSS : no histogram, nor exposure, gamma and whatever have been modified. The image in DSS looks sometime totally dark...but hopefully it doesn't affect the next stage of processing  I've processed the "raw" FITS later in Pix. How do you manage stacking and export in DSS? All background in your images are very dark, and contrast looks to strong as well, to my humble opinion. If you need more support, feel free to send me your FITS image to discuss more about stacking and processing  ;)  There is also a BatchPreProcessing tool in Pix, so you could compare your stacked image with the one from DSS. Make sure to check Pure Raw in Pix File Format > RAW  to let Pix interprets your CR2 files correctly.
Hope it will help a little.
Cheers,
Christophe

What ISO were you imaging at? I have the same ED80 scope and shot M51 with a Rebel T6i, see here M51, and then again with an ASI1600MM, see here M51, so the scope is capable of being used for some decent images of the galaxy. I personally don't like DSS for stacking and get better results doing calibration and stacking in Pixinsight. While processing, make sure you do all of your steps in small increments and don't take the background down so much.

I'd like to second what Thomas said.  When processing and stretching  do… not… make… zeros!  Leave a little space on the left side of the histogram until you get the exposure and contrast of your image correct.  Then you can start carefully clipping the background.

WRT cameras.  I have an uncooled ASI 1600MC and a Canon T6 and I cannot believe how much banding and color noise my Canon has compared to the ASI 1600MC.

Thank you all for your awesome suggestions. I would love to see what can be done with the raw .tiff image.
I uploaded it here: Raw image M51

I tried some of the suggestions. I still cant get the cool colors of the galaxy out. I really have no idea what goes wrong.  In photoshop I have to convert the 32 bits to 16 bits to do threshold processing, etc.. Then somewhere along the process I notice that it switches the mode to 8 bits.

Hi Mustafa,

Thank you for sharing the tif. In summary, I think DSS has killed half of the reds .

Checkout the histogram and the statistics:


Clearly, red has been seriously clipped, unlike the other two channels. By the look of it, the entire left side of the red histogram has been clipped. This is very big information loss and cannot really be repaired, also you are bound to have problems since you are essentially trying to process a GB image as RGB (ok technically it is 0.5R-GB but you get the idea) . It is probably not helping that all standard workflows published in tutorials generally assume no channel has been clipped.

I suspect the reason for the information loss is DSS's background calibration: if you have too much light pollution, this affects Red which has huge values. DSS will try to bring the background (i.e. most of the pixels) as close to 0 as possible, so it subtracts (or divides by?) a very large number. Think about it: if your signal is 2-3 and light pollution is 50000, it is very easy for a naive algorithm to decide that "background" is 50002 and thus turn all the 2's in your data to 0's.

You probably want to fiddle with the Per Channel Background Calibration checkbox (if it was on try off and vice versa), or better use PixiInsight for the integration.

Now, with the reservation that the Red channels is missing a lot of data, I was still able to pull out  what I think is some extra detail from your file. The result is not very pretty but I only spent 15 minutes on it, it's what I usually do to see "what's there".



The processing workflow was very basic and quick. On PixInsight:
- Crop
- AutomaticBackgroundExtraction
- PhotometricColorCalibration (it was quite tricky getting the settings for Background Neutralization right which was were I started to suspect something was wrong with the data)
-MaskeStretch + a little exponentialtransform to lighten the result, this is actually a very quick and dirty way to stretch without burning the stars

Then I brought it to Darktable for some very basic denoising, temperature adjustment (would not have been necessary if it wasn't missing so much red) and highlighting of the spiral arms with Equalizer (corse preset - Softlight blending) which I have found to be very similar to PixInsight's MultiscaleHDRTransform.

In conclusion, I think you can pull a truly amazing result if you ensure red is not clipped so early in your workflow. Tell DSS to leave background alone (or better:  use PixInsight for the integration, or Siril which is free software, both will do a great job) and be amazed.

Cheers.
Dimitris

PS as a secondary remark, I did observe a checkerboard pattern in your background. It is not so significant but if you want to be able to stretch your image as much as possible, I think you should use Bias frames (or if you are using them already, try using more of them). Luckily they are the easiest type of calibration frame to obtain.