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The Trifid Nebula (M20/NGC 6514) GRAS 003


bazza

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GRAS 003 is a TAK TOA 150 with a SBIG ST-10XME.

This is:

Lum 6 x 600sec Bin 1x1

Red 4 x 300sec Bin 2x2

Green 4 x 300sec Bin 2x2

Blue 4 x 300sec Bin 2x2

Aquired courtesy of GRAS, but processed in MaximDl, and Photoshop by me!

I would welcome criticism on the processing as this is why I'm using GRAS at the moment - trying a crash course!!

Barry.

post-13206-133877342524_thumb.jpg

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This is a lovely image - well done. With regard to criticism (constructive I hope!), I note that some of the stars have very 'sharp' white centres. I cannot be sure as I don't use convolution presently as I haven't got to grips with it but in essence this is a sharpening technique and I wonder if this has been slightly overdone, resulting in some of the stars looking unnatural? The nebula itself is nicely processed and presented - I'd have been thrilled to have taken this!

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Steve,

Thanks for the nice comments.

I did deconvoluve the image and I think I did too many iterations so I'll have another go with less. This was with 4 iterations each on L, R, G, B - think I'll try two on each. I'm sure learning how to aquire images with a telescope when I first started astro imaging, was easier than processing!

Barry.

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Barry, a useful technique that can work well on LRGB images is to subtly sharpen the luminance channel but don't do the R, G & B channels! I know this sounds counter-intuitive but the eye is much mire sensitive to contrast changes than it is to colour changes (hence people often bin their RGBs 2 x 2 but take their luminance binned 1 x 1). Try it and see, you may be pleasantly surprised.

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Hi Bazz, as Steve says the stars dont look right , but the nebula itself has come out very good , colour balance looks fine to me , i always find getting the stars good in LRGB pretty hard myself , so a huge learning curve i guess , no doubt others will give a more constructive advice on the processing , but on the whole a very nice image , just keep practising.

Rog

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Nice image Barry, No criticism from me, I leave that to the guys who know what they're talking about. I just see a lovely object, which no doubt you will work on a bit more in light of the advice given. Great job though. nice to see Southern Hem. stuff too.

Ron. :D

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Ok - I followed Steve's advice and just deconvoluved the Lum frames with just two iterations. Left the RGB alone.

See what you think about the stars again - I've looked at this for that long, wherever now, all can see is Trifid nebula's!!

Barry.

post-13206-133877342532_thumb.jpg

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A really interesting comparison, Barry. I have to say that I think the stars in the second image are more 'natural' and less 'processed' but I prefer the nebula quality in the first image!

I suspect that a final experiment might be to decon. both the L and RGB sets but with just 2 iterations although I suspect that the detail in the original nebula was a result of the 4 iterations in the L channel.

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Steve,

I will have a go with 2 iterations on each as you suggest.

I suspect though, this could be a tomorrow job, as the wife is about to serve divorce papers on me, stating I'm having an affair with a computer!!

Barry.

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