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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:
Disclaimer - My processing skills are at best, average. This thread is by no means a definitive test. Its just my observations.
I took some long exposures in Narrowband at 600s using the ASI183mm Pro camera and found that sometimes I could eliminate the Amp Glow from the middle right hand side using Darks and Flats and sometimes I could not. No idea why! Any help appreciated.
I found it easy to remove the glow when imaging at under 120 seconds a sub. This gave me the idea of trying to eliminate amp glow and noise by imaging at short, 10 second exposures, to see the results.
The one thing I failed to realise is the amount of disk space needed to process 200 x LRGB from a 20Mp camera ? The Registered and Calibrated files where 60Gb each!!
Processing on a External USB3 disk on a USB3 port on i7 with SSD and 16Gb RAM took best part of an hour. Not counting the restarts due to having other things running or lack of disk space etc.
Here is the result. Slightly cropped as it was taken over several nights and I did move the camera.
200 x LRGB at 10s
ZWO ASI 183mm Pro
TS 65/420 Quadruplet
Thanks for looking.