N3324 Gabriela Mistral Nebula in HHOO

[brajoh (John bradshaw)]

Another narrowband post for comments -- contrasty, colourful, saturated, sharp ... artificial in my opinion. I suppose that comes under taste.

[rustigsmed (Russell)]

not bad John, perhaps a bit extreme on the contrast / saturation for my tastes but gabriela looks sharp.

cheers

[jahnpahwa (JP)]

Originally Posted by rustigsmed

not bad John, perhaps a bit extreme on the contrast / saturation for my tastes but gabriela looks sharp.

cheers

Agreed, Gab looking super sharp there

[Placidus (Mike and Trish)]

The very separate tangle of H-alpha shock fronts at bottom left looks so different to the OIII rich Gabriela Mistral.

Good work.

[PKay (Peter)]

Hi John

I like it, you have used the palette to great effect.

A lot of detail has been revealed and that is most interesting.

Well done.

[Ryderscope (Rodney)]

Definitely an image with plenty of punch and impact John. The bold palette works for this image.

[Andy01 (Andy)]

A bold impactful presentation that unfortunately falls flat on close inspection.
Bloated stars and heavily clipped blacks suggest way too heavy handed processing in my opinion.
Your treatment of the Running chicken is much more subtle by comparison.

[Geoff45 (Geoff)]

Originally Posted by brajoh

Another narrowband post for comments -- contrasty, colourful, saturated, sharp ... artificial in my opinion. I suppose that comes under taste.

Unusual

[strongmanmike (Michael)]

Don't mind the colour palette.

Love that crisp edged cave-like structure, aka Gabriela's profile

Mike

[brajoh (John bradshaw)]

Andy, thanks for the constructive comments -- very obvious when you say so about the stars -- I have a bit of an addiction for Autohistagram for getting contrast so I'm sure you're right about the clipping - not sure how to check for that myself.

I reprocessed with star removal, read Ha only stars (all white but at least sharp) and reprocessed from preprocessed masters using NBRGB script to get what I feel is a much more pleasing colour balance with still a focal point at the "face". I would be grateful for your comments again.

[Andy01 (Andy)]

Originally Posted by brajoh

Andy, thanks for the constructive comments -- very obvious when you say so about the stars -- I have a bit of an addiction for Autohistagram for getting contrast so I'm sure you're right about the clipping - not sure how to check for that myself.

I reprocessed with star removal, read Ha only stars (all white but at least sharp) and reprocessed from preprocessed masters using NBRGB script to get what I feel is a much more pleasing colour balance with still a focal point at the "face". I would be grateful for your comments again.

Hi again, yes much improved imo.
The subtle nebulosity is revealed and the colour palette is much more appealing.

Best avoid any kind of auto stretching and keep a close eye on the histogram so the foot is well clear of the far left hand side.

There's still something odd about the appearance of the stars though? They're not that sharp or round, and have pronounced haloes.

Not sure which technique you're using there, but Starnet++ could be worth visiting to initially remove them, then create your HaRGB composite with colours & density to your personal taste. Then layer the original Ha with the stars still intact over the top as luminance only.

Assuming your original Ha image has no tracking, spacing or tilt issues and was well focussed, your stars should look good!

Hope that helps

[brajoh (John bradshaw)]

Bit cheap and nasty on the stars I'm afraid - I used starnet on Ha and O3 separately, both for starless and stars, and just stuck Ha stars back in with Pixelmath at the end — looked clean (but colourless), sharp on my little mac air that I process on, but you're right in that they are pretty obviously distorted on the larger screen of my email computer.
I am using a meade refractor with orion focal reducer (ZWO178MM=small chip small pixels) and thought it was ok for Ha stuff but stars are definitely distorted on the outer fields.
Interested in your comment about stretching. I use PI: cosmetic correction, then weightedbatchpreprocesing, then I used masked stretch separately on Ha and O3 (seems to give much less bloated stars and less noisy looking pictures than HT) and then maybe a bit of HST kick at the end if needed (more often not). Other mucking around with masks, pseudo green, auto histogram, DarkStructureEnhance script, sharpening and maybe some noise reduction/background decrease saturation and smoothing etc (before and a little after combination). Then I use LRGBcombination and adjust channel intensity and (increase) saturation and not very often adjust lightness.

[brajoh (John bradshaw)]

I appear to have the same problem with stars using a completely separate outfit of Celestron 8SE SCT with Celestron 0.6 Focal reducer. But that was with a 4/3 chip so I mentally blamed that on gear and haven't got back to check otherwise (read cloudy skies and other commitments).
The FR pamphlet suggests that it won't fully flatten the field and I notice there are virtually no photos of the day on AstroBin taken with an 8inch SCT (although I have also read the comments that say poor collimation is almost universal on SCT's). Focus is done early in cool down and largely left for the evening/night so I can see some weak links that won't get fixed til retirement ...

But odd for two different setups that the stars aren't right in a fairly similar way— if its old gear I cant change that easily / yet.
I guess I am heading for newtonian in the future so colours focus better — Ha and O3 seem to have different focus points on both my rigs.

[petershah (Peter Shah)]

Wonderful detail in it...