Flaming Star in SHO

[Tommohawk]

I've unofficially renamed this as "flaming nuisance". I don't think I've spent so long on any one image before - but reasonably happy with the result, though I have cheated somewhat with the processing so this is more about a "pretty picture" than astronomical data!

Done with Sharpstar 61EDPH + ASI1600MM cool + the newer ZWO NB filters.  Processed with  Astropixel processor and stretched in APP using the lowest default setting and then transferred into PS. Used a mask created from the OIII layer with  tons of contrast and then blur. The mask was then use to selectively enhance the OIII areas to bring out the blue, and a reverse mask was used to reduce the Ha and increase the SII elsewhere. I also blended some Ha with the SII to prevent the whole thing being a bright green splodge.

I also tried Starnet++ for the first time - makes amazing starless images! But then I struggled to bring stars back in without them looking "stuck on". In the end I put most of the stars back - but the background detail of the starless image seems somehow reduced with stars in place- odd! TBH as I look at this again now I'm wondering how this happens - some kind of optical illusion? 

Anyhow hope you like it and happy to receive comments.. BUT I would be even happier if you looked at my thread here on 16 Aurigae which developed as I was doing this and see what you think!!

 

[Sunshine]

Just beautiful!

[Davey-T]

A very pretty picture Tom, been trying to gather enough data on the Tadpoles here for a decent image.

Dave

[teoria_del_big_bang]

Very nice images.  I still think the star-less images look odd but actually that does make a very beautiful image and you can see so much more detail of the nebula, so maybe my opinion is changing.

Steve

[carastro]

That looks great Tom.  Don't worry about the processing, I think many people do this sort of thing who have been at it a long time.  I know I have resorted to similar on occasions and indeed some would call it quite acceptable.

I have recently done this combi myself, but didn't manage to get the Spider Nebula in as well.  I did nine in HaRGB so didn't have all your experiences.

Can't solve the weird star problem in your link though as it seems to be something transient hopefully it won't happen again.

Carole 

 

[Tommohawk]

On 03/02/2020 at 20:38, Sunshine said:

Just beautiful!

Thankyou!

On 03/02/2020 at 20:56, Davey-T said:

A very pretty picture Tom, been trying to gather enough data on the Tadpoles here for a decent image.

Dave

Thanks Dave. I didn't realise how much SHO detail there is in the individual areas - I'd like to redo this sometime with longer FL, especially the tadpoles.

On 03/02/2020 at 21:00, teoria_del_big_bang said:

Very nice images.  I still think the star-less images look odd but actually that does make a very beautiful image and you can see so much more detail of the nebula, so maybe my opinion is changing.

Steve

Yes, I think starless images look quite unnatural, but somehow you can see more detail. I'd like to try and perfect a way of reducing the star numbers without the "stuck on star layer" look. Maybe that would be a good compromise. I think maybe doing the stars with a lightest of stretches might be the way to go - should help  keep them small and preserve colour. Starnet does such a good job of removing stars it should be fairly easy.

BTW The starless version did have some artefacts round the bright stars which I removed with a clone stamp - very naughty, never done that before!! 

On 03/02/2020 at 21:04, carastro said:

That looks great Tom.  Don't worry about the processing, I think many people do this sort of thing who have been at it a long time.  I know I have resorted to similar on occasions and indeed some would call it quite acceptable.

I have recently done this combi myself, but didn't manage to get the Spider Nebula in as well.  I did nine in HaRGB so didn't have all your experiences.

Can't solve the weird star problem in your link though as it seems to be something transient hopefully it won't happen again.

Carole 

 

Thanks Carole - yes I guess you have to be a bit creative... its just rejigging the image rather than adding artificial data. After all, SHO is all false colour, so  why not!

[carastro]

Quote

 rather than adding artificial data

Yes that's when it becomes acceptable.  So long as it is all your own data I think you can combine it anyway you like to achieve a good result.  Many experiment with this sort of thing.  

Carole 

[Adreneline]

I'm a fan of starless images of nebula and yours reveals a lot of detail.

I've been playing removing the stars from all my past nebula images just to get an alternative view of things - and to practise using Starnet++.

Thanks for sharing Tom.

Adrian

[MartinB]

Lovely work Tom and a great FOV.  One of the problems with Starnet is that you get these dramatic starless images and you then want to preserve the drama whilst bringing the stars back in.  This can be very tricky to do without the finished result looking odd e.g. stuck on or fuzzy stars.  For a long time imagers have been trying to reduce star bloat with varying degrees of success and failure!  One very simple technique in PS is to add the starless image as a layer above the starry one and then reduce opacity to something that gives you the blend you want.  It might or might not work for you.  

Because the area you have imaged is Ha dominant the image is rather green except for that lovely OIII region around the tadpoles.  This is great in that it shows where the ha is but green does tend to jar in astro images.  There is a free photoshop plug in called HLVG which can very easily transform that colour scheme giving the more familiar golden hues.  I believe it is free and is well worth adding to your processing arsenal.  You can select different strengths of colour transformation.  Personally I like to leave a little green in the mix since that leaves some trace of the emission line mapping.

[Tommohawk]

5 hours ago, MartinB said:

One very simple technique in PS is to add the starless image as a layer above the starry one and then reduce opacity to something that gives you the blend you want.  It might or might not work for you.

Hi Martin - thanks for your kind comments! The framing worked out really well, but TBH more luck than judgement! 

I tried reducing opacity in the star layer, and I also tried switching the layers, and putting a reduced opacity layer under and over the nebula - I guess switching the layers doesn't really make any difference.

I may be wrong, but the main problem seems to be that when using a star layer with reduced number of stars, only the star centres are selected, so they are a fairly uniform hue / intensity.  Even with the lowest default stretch in APP the stars are pretty big. I wondered about using a really teen - weeny stretch to minimise the size, and hopefully keep more dynamic range. But by the time I had that thought I was exhausted and just left it!