Hope you all had a great Christmas I'm loving the holidays and no school anyway I haven't been able to do much imaging lately so I downloaded some raw data from Astrobin taken by DavidNG of M42. The images were in narrow band (Ha,Olll, Sll) and at first I thought I’d make the everyday false colour image but the weird star colours turned me off. So instead, after much pain and agony I have attempted making a true colour image from the narrow band. The images were blended in Nebulosity like this: Red, 80% Ha + 20% Sll . Green, Olll. Blue, 85% Olll + 15% Sll. And then lots of fiddling, I have never done this before so I’d love to know what you reckon.
Good attempt to get 'normal colours' from narrow band. Nebulosity is still a good program for processing but you sometimes need to do some back flips to get the best out of it. It looks like you have a handle on those gymnastics. PixInsight is more capable software but at $300.00, I needed a pressbrake more than the software.
I know what you mean with limited time for imaging. Every time I have been to the Warwick property the wind has been blasting or the clouds menacing. Pretty hard to image at long focal lengths with that.
Cross fingers we have better weather over the next couple of weeks. Rain heavy in the morning and clear skies at night.
That's a pretty good attempt, Jo, and better than I would have though possible. A Ha/OIII/SII narrowband capture is missing a lot of spectral information.
Good attempt to get 'normal colours' from narrow band. Nebulosity is still a good program for processing but you sometimes need to do some back flips to get the best out of it. It looks like you have a handle on those gymnastics. PixInsight is more capable software but at $300.00, I needed a pressbrake more than the software.
I know what you mean with limited time for imaging. Every time I have been to the Warwick property the wind has been blasting or the clouds menacing. Pretty hard to image at long focal lengths with that.
Cross fingers we have better weather over the next couple of weeks. Rain heavy in the morning and clear skies at night.
Thanks Justin, yeah I'm beginning to figure out how to get the most out of Nebulosity. It's a bit of a shame there is no gradient removal, would come in really handy for my wide fields.
What are the skies like at Warwick? I live north of there, pretty much due west of Toowoomba.
I never had much of a problem with wind when using my horse shoe mount (it's rock solid) but recently I got a GEM and at 1200mm FL any wind really mucks it up. I'm looking into adding a ST4 port to the hand piece on my horse shoe mount so that I can set up auto guiding, can't wait
That's a pretty good attempt, Jo, and better than I would have though possible. A Ha/OIII/SII narrowband capture is missing a lot of spectral information.
Cheers,
Rick.
Thanks a lot Rick, I'm glad you liked it I'm pretty happy with how the colours turned out, the blue was difficult but to my eye looks OK now. I couldn't seem to be able to get any colour into the stars, other than the big bright blue ones, not sure why.
This is really encouraging - that's not a bad approximation at all. Nice bit of lateral thinking. It should be relatively easy to take some short RGB subs and put the star colours in as well.
chers,
Andrew.
This is really encouraging - that's not a bad approximation at all. Nice bit of lateral thinking. It should be relatively easy to take some short RGB subs and put the star colours in as well.
chers,
Andrew.
Thanks Andrew, what do you reckon would be the best way to add RGB stars?
I had no problems with wind on the horse shoe with the Meade SN10 but stepping up to the f4.5 16 really adds extra sail area which is even more punishing with the longer focal length. I will say thought it takes a 20 knot breeze to be noticed and we get them quite a lot of them at Freestone.
How are your sky's out your way? I have reasonable seeing most nights and have very dark SE sky up to the zenith.
what do you reckon would be the best way to add RGB stars?
I have spent a fair amount of time experimenting with methods for doing this in PixInsight. Similar techniques can probably be used in other image processing packages...
The best way I have found so far is to decompose the NB and RGB images into CIE L*a*b* channels. A star mask is used to protect everything except the stars in the NB a* and b* channels. Blend the RGB a* data into the NB a* and the RGB b* into the NB b*. Then recombine the NB L* with the modified NB a* and b* and voila! This works well because it only changes the colour of the stars and leaves the stellar profile (Lightness channel) unchanged.
I have spent a fair amount of time experimenting with methods for doing this in PixInsight. Similar techniques can probably be used in other image processing packages...
The best way I have found so far is to decompose the NB and RGB images into CIE L*a*b* channels. A star mask is used to protect everything except the stars in the NB a* and b* channels. Blend the RGB a* data into the NB a* and the RGB b* into the NB b*. Then recombine the NB L* with the modified NB a* and b* and voila! This works well because it only changes the colour of the stars and leaves the stellar profile (Lightness channel) unchanged.
Cheers,
Rick.
Thanks Rick - I'm going to try that too!
Cheers,
Andrew
I have spent a fair amount of time experimenting with methods for doing this in PixInsight. Similar techniques can probably be used in other image processing packages...
The best way I have found so far is to decompose the NB and RGB images into CIE L*a*b* channels. A star mask is used to protect everything except the stars in the NB a* and b* channels. Blend the RGB a* data into the NB a* and the RGB b* into the NB b*. Then recombine the NB L* with the modified NB a* and b* and voila! This works well because it only changes the colour of the stars and leaves the stellar profile (Lightness channel) unchanged.
I had no problems with wind on the horse shoe with the Meade SN10 but stepping up to the f4.5 16 really adds extra sail area which is even more punishing with the longer focal length. I will say thought it takes a 20 knot breeze to be noticed and we get them quite a lot of them at Freestone.
How are your sky's out your way? I have reasonable seeing most nights and have very dark SE sky up to the zenith.
Justin.
Skies are pretty good out here, various light domes on the horizon but they don't go higher than around 25 degrees, on a good night at the zenith you can see at least mag 6+, seeing isn't that great though. Dead flat farming country around here so a clear 360 horizon.
The Bunya Mountains are just over an hour away so I wouldn't mind seeing what the sky is like from up there. Having been up there in the day it makes you cringe seeing all the dusty skies down over the plains.
Jo
Last edited by nebulosity.; 31-12-2013 at 05:13 PM.
Thanks a lot Ross yeah I got a better result than I was expecting, I think with some RGB stars it would be quite nice. Would love to have a go on a different object to see how it would come out.
I'm loving the holidays and no school 
anyway I haven't been able to do much imaging lately so I downloaded some raw data from Astrobin taken by DavidNG of M42. The images were in narrow band (Ha,Olll, Sll) and at first I thought I’d make the everyday false colour image but the weird star colours turned me off. So instead, after much pain and agony I have attempted making a true colour image from the narrow band. The images were blended in Nebulosity like this: Red, 80% Ha + 20% Sll . Green, Olll. Blue, 85% Olll + 15% Sll. And then lots of fiddling, I have never done this before so I’d love to know what you reckon.
