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eshy76

First Image of 2019: M45

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Hi everyone,

One and a half clear nights for me early in the year and I focused on M45. As a naked eye visible target, I think subconsciously I never gave M45 the concentration it deserves, thinking I could always catch it another time.

Anyway, despite lusting after the Horsehead, I kept my refractor pointed at the seven sisters in new moon skies and the result is below.

I actually found it pretty hard to process...the seven sisters themselves were pretty well behaved, but I couldn't decide what to do with the background. I know this is a dusty region so I did not want to put DBE samples everywhere. But at the end the background seems a bit smudgy after tweaking curves - I'm not sure whether to darken the background or leave it as is.

3.4 hours of LRGB integration. Full details on Astrobin.

Thanks for looking!

M45 08-01-19 (Downscaled)-909x687.png

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When in doubt (which is often!) I put a marker in the darkest possible place close the each corner. Just four markers work pretty well in these cases. I also even things up with a dose of SCNR green as the second adjustment. I'm not sure about that dark patch left of the main cluster. Is it in the data when give a stretch and no other processing?

Olly

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Thank you for the tips Olly  - I'll give the 4 corners pointer a try. As well as my STF data, I tried to look at reference images to judge the DBE points and they were mainly on the left of the cluster...maybe that explains the dark patch! I'll check my data again later - I think it was actually pretty clean, so my processing is what probably what needs to be looked at and the initial DBE is a strong potential culprit. 

I did SCNR green on the RGB data, but when stretching, started to move the channels around - the black points of the R and B channels were off, but I guess the second I start adjusting those, colour balance (I had done PCC earlier too) starts getting messed up?

The data is there, though, so I can definitely reprocess to do it full justice - it was refreshing that it was hard to mess up the main cluster no matter what Pixinsight tool I used...so I'm convinced there's a better M45 image in there!

Thanks again!


 

Edited by eshy76
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I always think it's risky not to have four corners sampled...

Olly

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So I gave this another go in terms of processing - more use of DBE...more controlled background.

I think I had flats issues too - I committed the cardinal sin of connecting the imaging camera to my USB hub instead of the mini pc as I always have before - I noticed some patterns in the flats that weren't there before. Never change a setup that works if it can be avoided!

I think this looks better!

540811363_M4508-01-19(Reprocess1-Downsampled)-900x679.png.0ad233f5559e75853bcd7d79b47dc150.png

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wow, quite a bit of difference to the first image, looks a lot better now.

well done.

Paul

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1 hour ago, Nick Smith said:

Great job!  Hate to say it though, probably slightly out of focus??

Thanks Nick - yes probably - that was my last shot before I installed my Lakeside focuser, which is yet to see first light...hopefully focus issues will be a thing of the past soon!

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1 hour ago, ultranova said:

wow, quite a bit of difference to the first image, looks a lot better now.

well done.

Paul

Thank you Paul - I'm still trying to work out the balance between over and under processing images. I want authenticity as much as possible, but clearly the light touch I used in the first attempt left major background issues. So I was less subtle with DBE (Pixinsight) the second time around!

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