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This is maybe my 3rd attempt at a galaxy and I am trying to figure out the best way of doing it since I live in a red zone of London suburbs.
I took this over 2 nights (well, 1.5 really, as my guiding wasn't working and plate solver wouldn't comply after meridian flip...) with my 8" EdgeHD SCT with 0.7x reducer and Atik 490X. Around 20 Luminance subs at 10 mins each (1x1) and around 15 RGB subs at 5 mins each, but binned 2x2. I use Astrodon filters but also have an LP filter permanently in my image train.
Question: should I only use RGB and create a synthetic L channel, given LP, or continue trying with the actual luminance? Gradients are horrible with luminance but RGB doesn't have as much detail (only red filter seems to be more sensitive).
My stars are all over the place (colours pop out everywhere, in the wrong way), how can I control this better?
Also, as I wrote, the red filter seems to have much more detail than the rest and when I add all the channels into PS, the red colour just overpowers everything (and in general, how can I keep the star colours as they are and not have the red and blue go crazy - I am not sure the name for it, but it looks like chromatic aberration on steroids).
Any other general tips would be great...
Thank in advance. GFA
PS: I cheated with the core: just changed the temperature to make it look a bit more glowy; for some reason, I barely had any yellow colour from the data...I will post stacked images, if of interest.
So with no new data at hand (or on the horizon it would seem) i decided to go back and re-process my short stack of M81 & M82, being the glutton for punishment that i am! The last time i re-processed this was about a year ago, so i was curious to see if i could get any more out of it.
It's hideously low on data (nothing new there!), this is just 9 x 600s of colour (with an IDAS-D1) together with 7 x 1200s of Ha (which i only used to Lighten the Reds in the Ha jets of M82 and the small spiral regions of M81). AstroPixelProcessor used for stacking and gradient reduction, and PS for everything else.
I mistakenly shot the colour at ISO 800, instead of the usual 200 i always use. A mistake i imagine every DSLR user has made before! And i have to say i really noticed it during processing. There was noticeably less colour in the stars.
That being said, i was still able to bring out more colour in the core of M81 this time. And i think M82 looks a bit better as well, it was definitely over-sharpened before.
I really love these targets, but they just make me wish i had more reach!
Here is the original thread:
And here's the new one, including a cropped version:
A new camera, means a lot of testing and seizing every possible clear night at your disposal. I used the first nights with my "ZWO ASI183MM-Pro" shooting hydrogen alpha, but now I wanted to test it on a broadband target.
And what better test-subject than good old Bode's Galaxy/Nebula, for this image size!
Upon processing the 3,6 hours worth of luminance data, I then realized that I missed the color in the image. So I went digging for the last images I shot of M81, which was with a Nikon D5200 sometime last year.
I aligned the images and set the old image to color, and got this as my final result.
I must say though, that I've probably gone through 20 different renditions of this one, as I kept trying to improve it, and finding a new favorite image But here is the last one I came up with, together with the separate luminance data and the 2017 M81 image
Upon further investigation, I've noticed some dust-motes that has snuck into the image... Guess I need to figure out how to do flats.. They were never really necessary when shooting with the DSLR as noise would be too high anyway if you stretched it this much.
Shot with: ???⭐?
ZWO ASI 183MM-Pro (Nikon D5200)
Celestron Advanced VX Mount
Explore Scientific Coma Corrector
Baader Neodymium Filter
213 Minutes Luminance (4 Minute + 8 Minute Subs)
136 Minutes of Color DSLR (2 Minute Subs)
Combined Image (5.816 hour data)
Luminance Data (3.6 hour data - ZWO ASI 183MM-Pro)
DSLR Image (2.26 hour data - Nikon D5200)
Any advice or thought are accepted with open arms!
One thing I know myself, is that I need to improve my mounts PEC data-set, to improve my guiding. It worked very well when I first did it, but that is like 1,5 years ago now.
M81 Bodes Galaxy and M82 Cigar galaxy. Taken last night 23rd April despite a bright moon. 120 x 60 sec lights, 40 darks. No bias or flats as I'm having a bit of problem with my flats at present, they seem to make things worse not better. Taken with Canon 1100d unmodified with a Celestron C8 on an HEQ5-pro. Processed in DSS and Star Wars (Sorry Star Tools).
The Star Wars connection?, well you can see that M82 is better illuminated while M81 is on the Dark side. It was reported that a supernova was observed in Bode’s Galaxy in 1993, however it is much more likely that M81 was the location of Alderaan. destroyed by the Death star in the first 1977 movie and we viewed this event 12 ish million years later given that M81 is 11.8 million light years from Earth. If this sounds a bit far fetched remember that the story was set "A long time ago in a galaxy far, far away" so it sort of fits. If you don't believe this then all I can say is that "I find you lack of faith disturbing"