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NGC 7635 - Bubble Nebula narrowband (14+ hours)


x6gas
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I've spent the week capturing narrowband of the Bubble Nebula with my EdgeHD only to find last night that the collimation of the scope is off. I adjusted it using a Duncan mask and thought I had it bang on, but it turns out I was probably dropping the scope out of collimation so I have poor star shapes in one corner :mad:

Anyway, this is a full reprocess Ha: 23 x 600s & 11 x 300s; OIII: 10 x 900s & 25 x 600s; SII: 23 x 900s

Scope: 11" EdgeHD @f/7 w/ Celestron 0.7 reducer

Camera: Atik 490 ex, binned 2x2, 2" Baader Ha 7nm filter

Mount: CGEM DX

Guiding: Atik OAG, QHY IMG0H, PHD ~ 0.6 rms

I may yet capture RGB and do a narrowband enhanced version, but for now I'm waving the white flag on this one.

This one before HLVG:

gallery_11821_2457_429946.png

Full size version here.

This one after:

gallery_11821_2457_582534.png

Full size version here.

Cheers, Ian

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It is absolutely gutting seeing such a quality image then reading the collmation was out. Its like you've won the grand national on a one legged donkey...most of us couldnt get the blumming donkey to stand let alone win.

Great image!

Sent from my GT-I9003 using Tapatalk 2

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now, i make no excuses for hijacking this thread....because my motive is to show just how good Ian's / x6gas's picture is in comparison to mine...which can be seen here: http://stargazerslounge.com/topic/190094-hubble-bubble-a-whole-lot-of-trouble/

see what i mean. yeh sure i'm quite pleased with mine....but when i saw ian's above, my heart sank...

bob

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@ Ultranova: Thanks Paul, much appreciated.

@ ncjunk: Yes Paul, I was pretty gutted when I realized. Yet another rookie error on this capture. I'll chalk it up to experience and at least I won't be making that particular error again!

@ Amra: Many thanks!

@ cloudbuster: Ha Bob. 14 hours of data helps and it's never good enough is it! I can already see several things that are still driving me nuts on my version...

@ RobH: Thanks Rob. The Celestron reducer is a solid bit of kit but if I am totally honest I think the poor collimation makes it hard to determine whether it is actually any better that the Optec Lepus unit I had been using. I don't have an after market focuser. Well, that's not quite true; I have a lovely moonlite, but can't use it for imaging with the OAG as it adds too much to the back focus. So it's fine tweaks with the stock focuser and the help of Bhatinov Grabber!

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Hats off Ian. Very nicely done. I realized that you prefer using HLVG at the very end of your processing. Would it make any difference if you used it say somewhere in the middle?

Thanks moxican. I'm not sure at what other point I could use HLVG. I work on processing the different narrowband channels and then do a colour combine in PhotoShop. At that stage it is all about tweaking the colours. I'd welcome suggestions of alternative workflows!

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Nice job. Shame about the slight collimation issue, though it doesn't impact much.

Thanks Freddie. Yeah I'm annoyed about the collimation... can't believe I didn't spot it sooner but now I know the fault is there... so I may try to correct those troublesome stars.

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It's a great image Ian, and you've nailed the colours now as well, lovely blue hues couples to rich golds - great!

Martin

Thanks for all the encouragement Martin. By the way I think I may have found a solution to the brown sky problem (though it's difficult to tell on this object as there is lots of faint nebulosity all over the background... Anyway: I put a Colour Balance adjustment layer in, and on the shadows tone balance I move the cyan / red slider to around -18 and the yellow / blue to +20 and then uncheck the preserve luminosity box. I'd be interested to know if that works for you too...

Cheers, Ian

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I like this post HLVG version very much. The colours are just as Ilike them. A great image Ian and well worth persevering.

Thanks Sara - I really appreciate the encouragement. I did an RGB synth using the narrowband data too:

post-11821-0-44069900-1373822475_thumb.p

Edited by x6gas
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I do like the colours on the post HLVG version and the detail is amazing.

Dave

Many thanks Dave. Yes, I think the bluer / golder hues post HLVG are more pleasing. I have found with some objects that I lose something by taking the 'green' out - less colour range to bring out differences between the different components of the nebula... not really an issue with this, though. The OIII from the Bubble is really weak so I may yet try a bicolour with the Ha and SII... and I am still hopeful of getting some meaningful RGB, especially now I have cured the collimation issues I was having.

Clear skies, Ian

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