M20 Triffid Nebula HaRGB 15 hrs.

[montewilson (Monte)]

Nice work - this was done in Sydney ?

[iceman (Mike)]

It is a nice image Fred, but I know you'll be able to do better. I think the terrible seeing we've had over the last few weeks played the major factor in the softness.

[Bassnut (Fred)]

Thanks Ric

Jase, things started going pear shaped on loading in fits liberator, stuff it, Ill start again from scratch. Its a puzzle sometimes how different the results are in the liberators strectch algorithims with similar looking masters.

Paul, the problem is the raw data is often pretty ordinary to start with, this is not a top shelf rig, so it needs pushing, which the likes of Jase and Mike can immediately see. I lke the challenge, but it needs a hell of a lot of time in PS to go past the wow factor ,and please the eagle eyed in these hallowed pages.

Monte, yes, in Sydney on the Meade/G11.

Yes Mike, Im supprised sometimes at how clear the sky looks and yet subs look very soft.

[gregbradley]

Another great shot Fred.

I like it. It seems to me to be a matter of choice with this object. In Ha the blue nebula all but disappears (its reflection nebula not emission nebula). Ha will dominate the colour and fade out the reds unless layered in with the red channel and maybe a bit in luminance layer (Ha as luminosity layer). Rob Gendler posted a suggestion about how to combine Ha and LRGB recently. I can email that if you are interested (I haven't used it myself).

You certainly have gotten more detail of the various folds of the nebula more than is normal by a long ways.

If you don't like the stars perhaps try a short LRGB for the stars only and erase the Ha stars and layer in the short exposure. That way you get less tracking error, better colour and less stress!

Your 12 inch LX200 ACH and ST10 are a great combo.

Greg.

[Bassnut (Fred)]

Thanks Greg. Yes, im aware of Ha/red blending, but haveing tried it recently on this, 3nm Ha subs are very different to regular red subs, they dont mix well, light pollution, and the emission/reflection neb mix might be a factor there on M20.

You have a good point there though, Im thinking of taking lum and adding it to the red, and using it to extend the reflection nebula, whilst leaving the core largely Ha to retain the detail.

Although 3m Ha gives an amazing result, it is difficult to blend with RGB, especially the stars which are tiny compared to RGB.

A short exposure LRGB just for the stars is an excellent idea, haddent thought of that. Come to think of it Greg, its all falling into place now, top input, thanks for that.