Horsehead Final Attempt - HaRGB

[Snoani]

I posted a capture of the Horsehead Nebula in the New Year that despite some issues I was really proud of.  However, it did come to my attention that it was a touch out of focus.  It looked fine to me on screen but less so when I tried to produce a print of it for my wall.  

Over the last few weeks I have therefore endeavoured to produce a better image of this target and overcome several trials during the process, including an unscheduled rain shower that breached my image train and prevented me from calibrating some of my lights.  It is more in focus than my other attempt but I am not sure about the colours.  

There only a little over 1 hour each of RGB and 1.5 hours of H-Alpha.  I have therefore had to work the data quite hard to produce this result and suffer a few restarts in the processing. 

As always health criticism is welcomed.  

 

[Adreneline]

FIrst off this is a really good image of the HH with some excellent detail in the nebulosity and the structure of the HH. To me the main issue is the stars. You don't say what scope/lens/camera you used so I may be well off the track with my comments so apologies up front.

I have had every problem going with RGB imaging, not the least of which was very different fwhm values for stars taken with each filter. I used to suffer from terrible 'blue bloat' giving rise to significant bluw halos around stars. I think it was either a feature of the doublet scope I used or a feature of the filter - I use feature as a euphemism for shortcoming.

I managed to ameliorate these features by reducing the star sizes in G and B until they were comparable with R; it wasn't a perfect solution but it did help.

You don't mention which software packages you use but if you use PixInsight you can remove the stars in the R, G and B channels and process them separately before recombining with the starless images. Working on starless images let you "work the data" more without compromising the stars.

Without doubt you have lots of good data to go at so it is worth a shot.

Adrian

[Gerr]

I really like this nebula in Orion. Trying to control the bright stars (esp. Alnituk) is always difficult in processing. The horse head and flame are captured really well and focusing seems fine but your stars do glow too green for me. I also prefer to compose the nebula in the centre of the image as it more aesthetically pleasing. You certainly have lots of H alpha - maybe too much.

Gerr.

[Snoani]

On 16/02/2021 at 20:53, Adreneline said:

FIrst off this is a really good image of the HH with some excellent detail in the nebulosity and the structure of the HH. To me the main issue is the stars. You don't say what scope/lens/camera you used so I may be well off the track with my comments so apologies up front.

I have had every problem going with RGB imaging, not the least of which was very different fwhm values for stars taken with each filter. I used to suffer from terrible 'blue bloat' giving rise to significant bluw halos around stars. I think it was either a feature of the doublet scope I used or a feature of the filter - I use feature as a euphemism for shortcoming.

I managed to ameliorate these features by reducing the star sizes in G and B until they were comparable with R; it wasn't a perfect solution but it did help.

You don't mention which software packages you use but if you use PixInsight you can remove the stars in the R, G and B channels and process them separately before recombining with the starless images. Working on starless images let you "work the data" more without compromising the stars.

Without doubt you have lots of good data to go at so it is worth a shot.

Adrian

Thank you both for your comments.  It is always appreciated to receive feedback.  

My scope is actually a Meade 6000 triplet APO (with FPL-53) and a 1600MM Pro and I do seem to suffer with an issue where the colours form some of the brightest stars don't align well.  It is not a filter issue because I have noticed the same thing has happened when I was using a DSLR.  I wonder therefore if the lenses in the scope are slightly out of alignment.  If it is I don't know if there is somewhere that might offer a repair/fine tuning service.  

I don't have Pixinsight due tot he price of it and I am using a combination of Affinity Photo and an old version of PS for the action sets.  I will therefore have a play to see where I can rain in and amend the colour of the brighter stars 

[Adreneline]

3 hours ago, Snoani said:

If it is I don't know if there is somewhere that might offer a repair/fine tuning service. 

I am sure there are but I can't advise on that one or who. However, have you seen these or read up on them - might help you confrm if there is an issue or not.

Edited February 18, 2021 by Adreneline

[Snoani]

I decided to give it a second try.  I think I have manage to control the brighter stars better, although I have not completely removed the green from some. 

It has certainly stopped the light from Alnitak from overpowering the colour in the Flame Nebula.  The only thing is that I would like to see the nebula with a touch more red but I have had to sacrifice this to balance the image as a whole. 

 

 

Edited February 20, 2021 by Snoani