Orpington Astronomical Society

Astronomy => Astrophotography => Topic started by: MarkS on Dec 07, 2008, 03:16:56

Title: M42 Work in Progress
Post by: MarkS on Dec 07, 2008, 03:16:56

16 x 5min
Modified EOS350D on Celestron C11 with F6.3 reducer and CLS filter taken from Sidcup tonight.  Size scaled down by factor of 2 and then cropped slightly.

Processing this data to make it look "right" will be quite a challenge because of the huge dynamic range.  But, in any case, here is a preview.  I also took some shorter subs which don't burn out the trapezium - somehow I need to combine that data in.

(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/normal_neb1280x1024.jpg)

Full size (1280 x 1024) here:
http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/neb1280x1024.jpg
Title: Re: M42 Work in Progress
Post by: Rocket Pooch on Dec 07, 2008, 08:46:07
very nice, it was clear last night and looks like it will be tonight as well, if so i'll be out at last....
Title: Re: M42 Work in Progress
Post by: Fay on Dec 07, 2008, 10:57:06
What a good start Mark. Really nice, look forward to seeing how it ends up after full processing.

I want to have a go at this, obviously, it will be all new to me, the processing with different length subs.
Title: Re: M42 Work in Progress
Post by: MarkS on Dec 07, 2008, 12:02:45

Last night, I also tried the nebulosity around Merope and also the Cone Nebula.  Neither came out well (even with the CLS filter) because the sky was very damp, which created a high level of background signal (hence noise).

Here's the (22 x 5min) full frame Christmas Tree shrunk in size by a factor of 5.   Because of the low quality, I haven't bothered to remove the background gradients.

(http://homepage.ntlworld.com/the_shelleys/Astronomy/xmastree.jpg)
Title: Re: M42 Work in Progress
Post by: Rocket Pooch on Dec 07, 2008, 12:54:13
ouch, well lets see how that 6" F5 newt is tonight, if its clear, on the SXD.
Title: Re: M42 Work in Progress
Post by: RobertM on Dec 07, 2008, 13:02:27
Excellent work on the M42 Mark, the dust really does look smokey.

Last night really was a bit strange, it started off frosty then all that melted and it turned very dewy around midnight then I wake up to see an extensive frost !
Title: Re: M42 Work in Progress
Post by: JohnP on Dec 07, 2008, 19:21:33
Another very promising looking image... John
Title: Re: M42 Work in Progress
Post by: MarkS on Dec 07, 2008, 20:35:09
This is about the best I can do:
(http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/normal_m42_061208.jpg)

Full size (1476 x 1096) is here:
http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/m42_061208.jpg

Balancing detail against noise is always subjective.  This time I've gone for more detail and contrast at the expense of noise.

Details as before:
15 x 5min (+ 4 x 1 min for the core)
Modified EOS350D on Celestron C11 with F6.3 reducer and CLS filter taken from Sidcup tonight.  Size scaled down by factor of 2 and then cropped slightly.  Ambient temperatue 0C.


Title: Re: M42 Work in Progress
Post by: Mike on Dec 08, 2008, 09:38:20
Very nice Mark. Colours look a bit weird, like it is lacking in Blue, but very nice anyway.
Title: Re: M42 Work in Progress
Post by: MarkS on Dec 08, 2008, 10:30:37
Quote from: Mike
Very nice Mark. Colours look a bit weird, like it is lacking in Blue, but very nice anyway.

Thanks for the comment.

The weirdness of colours will be partially (or wholly) due to the CLS filter.  It's lets through the narrowband Ha at 100% but severely curtails the broadband green and blue.  However, but boosting the blue also tends to boost a lot of noise and also makes the stars go blue as well.

I'd like to take this image again - next time from a dark site.  Watch this space ...

Mark
Title: Re: M42 Work in Progress
Post by: Mike on Dec 08, 2008, 10:57:32
I know it is a colour chip but have you tried RGB filters?
Title: Re: M42 Work in Progress
Post by: MarkS on Dec 08, 2008, 11:13:33
Quote from: Mike
I know it is a colour chip but have you tried RGB filters?

It wouldn't help.  My main problem is light pollution so I either need to use a CLS filter (or equivalent) or use narrowband filters.
Title: Re: M42 Work in Progress
Post by: A.S.I.G.N_Baz on Dec 10, 2008, 13:20:48
I actually quite like the composition of the cone nebula you have got there. Warts and all - Nice effect.

Baz.