Jellyfish in HaLRGB

[cfpendock]

This is the Jellyfish Nebula (IC443) in HaLRGB, taken with a 4" refractor and Atik 4000.  RGB was binned 2x2 - a mistake I think, but I wanted to save time because of the awful weather.  Red is blended with Ha to reduce the halos round the two Gemini stars. LRGB was 12 exposures each of 2 minutes.  Ha (7nM) was 9 exposures each of 20 minutes.

 

I am quite pleased with the image, but I feel the stars are not quite as I would like partly because of the Ha blending.  I need to experiment with blending the Ha as luminance to try and improve this.  Actually I would like to be able to afford an Astrodon Ha filter which I think might provide more detail in the nebula…….

 

Chris

[Epicycle]

Very nice image! The area around the jellyfish is fantastic, but those two stars are a nightmare for processing, aren't they?

Your set up gives a generous field of view for this.

What software do you use for processing? Pixinsight has a very nice masked stretch tool to keep stars under control, but they few times I've tried HaRGB I always ended up using the stars form Ha...

E.

[Martin-Devon]

Chris this has come out well, don't be so hard on yourself! Nice framimg and plenty of detail in there, the Gemini stars as you point out are headaches though.

Martin

[cfpendock]

Thanks Martin and Epicycle.  I used Photoshop for processing, but have to confess that I am very much an amateur when using this software.  When I first merged the RGB and saw the colour of the stars I was quite blown away, and that is why I wanted to use at least a part of the original red rather than just Ha for the red channel.  But I agree that Ha stars on their own are nice and tight - but the Gemini stars in the original Ha had enormous halos which I didn't like at all.

Thanks both for your kind words.

Chris 

[Ewan]

Did you bin the L as well Chris ?, RGB is fine binned as it cuts down time & it is after all for the colour, purists always prefer unbinned though.

More Lum data would benefit this image no end.

Much light pollution where you are ? if so Ha Luminance is a better option to grab that detail, maybe blend with some R as well as the target is mainly red nebulocity.

The stars look a little over stretched in PS & are dominating the image too much i feel, process the Lum using Layers / Opacity.

Apologies if my comments come over 'too negative', they are not meant to be as i too am still climbing that processing curve, i look forward to having a crack at this now i have seen yours but my fov wont be as good.

Noel Carbonis Photoshop Actions are well worth the small outlay Chris, about £13.00 i think & they help no end with particular techniques.

[cfpendock]

Thanks Ewan.  Any comments like this are extremely useful.  I did get L, unbinned, 11 exposures at 5 minutes each.   I pasted this on top of the  HaRGB.  

I don't have a great deal of light pollution, but I did have a problem with flats - had to try several times for each filter at different ADUs before they worked properly - not for dust, but for severe vignetting which I get with this set up.

I agree with you that more data would help this image - I'm just waiting for the weather! But particularly I think that I don't have enough time on the RGB, as well as the L, and I think next time I will try and get longer subs - using the originals to control the two stars, but hopefully getting more detail on the nebula.

Concerning Photoshop, I am not at all experienced with this, and at the moment have to force myself not to over-process.  I think that if I can find the time I will try and re-process to better control the stars.

Chris