IISAC 2009 - Tarantula Nebula (NGC2070)

Eternal · #1 21-10-2009, 08:17 PM

I thought having a modded camera and performing longer exposures would make processing easier. Boy was I wrong!!! After nearly three days of processing this image through Deepsky Stacker and Photoshop CS2 I've finally settled on the following version, which I'm sort of happy with.

My main problem was the over exposure of the centre which no matter what I tried, could not reduce in any way. Even the subs I took at a lower ISO level in anticipation of this problem made no difference as they too were over exposed in the centre.

What I ended up with is 30 x 2min ISO 1600 subs (24 selected) taken through a modded Canon 450D with Baader MPCC and Baader UHC-S filter with Nebulosity 2.0 (10 darks & bias frames, no flats because I forgot my light box).

The scope was an 8" Skywatcher Newtonian on a Skywatcher EQ6 with Synscan. Guiding was done through a Skywatcher ST80 with QHY5 autoguider PhD Guiding. Processing was done through DeepSky Stacker and Photoshop CS2.

Next time I'm going to try lots of 5 min subs at ISO 800 instead and combine them with lots of 1 min subs at ISO 400 to see if I can capture the core without burning it out.

multiweb (Marc) · #2 21-10-2009, 09:29 PM

Shame about the burnt core, but it's a superb picture. Loads of data you can get out still in there. Real nice. Top work.

alan meehan (Alan) · #3 21-10-2009, 09:30 PM

Hi Eternal dont be to disappointed its not a bad shot ,the tarantula is a tricky one to process its so tangled up with nebulousity ,you will find if you do your subs at iso 800 you will not burn out the core as much ,good luck and will see your next result.
ALAN

dpastern (Dave Pastern) · #4 21-10-2009, 10:01 PM

Eternal - that's a good attempt, plenty of detail there in those tendrils. You could always just grab some 1 min subs for the core and composite them over your current image like instructed here:

http://www.astropix.com/HTML/J_DIGIT/LAYMASK.HTM

of course, more data added to the image would be nice as well

I had a look at the image in PS and you've clipped the black point. From what I've learnt so far, that's not good and you'll probably want to re-process the data from this set and avoid clipping the black. See attached image for what I mean - try and avoid having the left hand side of the histogram creeping up and touching the left hand side.

Not trying to sound mean, just trying to help with my meagre knowledge.

Dave