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M51 Whirlpool Galaxy - EOS Ra first light


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This is from a couple of nights ago.

It clouded in quickly, so I didn't get much data. The temp was 2C, and I'm self-isolating - so that was also a factor! I only took 5 darks before I gave up and went to bed. I'll take more when the temp is right.

This is 140 min integration time on a new Canon EOS Ra with 17x500s exposures, and no filter (from the city).

Processed in PI and Photoshop - I should have used more star masks but the data aren't good enough to warrant the effort I think. I also had difficulty with flats - I tried a range of exposures with a Gerd Neumann panel, but I think they were all too short. Will go longer than 0.3s next time - very hard to figure out flat exposure on DSLRs, and APT's tool doesn't work for DSLRs yet.

I think I'm obsessed with M51 - and I know I'll be back to it again.

Stay safe everyone,



M51 Whirlpool Galaxy no flat or dark_integration_crop_lin fit_clone_DBE_ABE_MSLT_careful curves_vib sat.jpg

M51 Whirlpool Galaxy no flat or dark_integration_crop_lin fit_clone_DBE_ABE_MSLT_careful curves_tight crop_unsharp mask.jpg

Edited by EyeGuy
Added tighter crop and a little sharpening
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Lots of good detail! Color balance is definitely off. So, good that you could see that. I took the liberty (hopefully you don't mind) of pulling this image into Photoshop and looking at your individual color channels. As you can see in the histogram, there are different amounts of Red Green and Blue, and they don't align. Aligning the channels using the levels tool creates a neutral black. This brings the colors of the galaxy back in line, closer to where it should be. Depending on the program you use to process you should be able to achieve better color correction with the built in tools.

Here's your current image with the unaligned color channels. Best shown in the top histogram where you can see red, green, and blue not overlapping.


Here's a version where I simply aligned each channels histogram using the levels tool in Photoshop. Now you have a neutral black, and galaxy colors appear more correct. In any image processing program from here, you would isolate the galaxy with a mask, so that you can modify it, without changing the neutrality of the black background. You would then enhance the color of the galaxy through saturation and other color correction measures to get it to a more expected result.

Hope that helps.


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One note about your comment on flats. Turn on your DSLR histogram function if it has one. This will display a histogram like I show above in Photoshop on the back of your camera after each capture. Make sure the histogram (the hump of light) is bright enough that it falls squarely between the left and right sides of the histogram frame without being cut off on the left or right side. Alternatively, you can load your flat into Photoshop, and look at the histogram there to see the same thing.

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