Well, what a reprocessing adventure this has been!! After advice from Marcus regarding noise reduction and from Ivo Jager regarding my missing yellow stars, I went back and have spent the last couple of nights playing with the 2.75hrs of data I took last Saturday night from my backyard here in Brisbane. Now one of my problems is that the UHC-S filter that I use basically only lets blue and red light through, notching the spectrum for everything else. I've attached what I'd call a power spectrum (seismic processing talk) of the Baader UHC-S filter so that you can see what I mean. This means that it is very hard for me to get any yellow in my images - which is something I've noted, but never understood, when imaging galaxies.
Anyway, here's the repro of the Trifid Nebula. As mentioned in my last post, it's 33 x 5 minute subs using a GSO RC8 and an OSC QHY8L CCD. Hopefully I've got a better result this time, and for the observant ones out there, yes I have rotated the image 90 degrees to better match the orientation of Marcus' superb image.
Any comments on this version would be greatly accepted... Oh, and a big thank you to Marcus and Ivo for their advice that they gave - very helpful indeed!
Hi Mario,
Nice effort! I've been banging on about exactly that effect with the CLS CCD filter removing the yellow stars from my images too. Even wih R G B filters and a mono CCD I've yet to restore the yellow colours.
cheers,
Andrew.
Hi Mario,
Nice effort! I've been banging on about exactly that effect with the CLS CCD filter removing the yellow stars from my images too. Even wih R G B filters and a mono CCD I've yet to restore the yellow colours.
cheers,
Andrew.
Thanks Andrew, I'm glad you liked it.
I've been looking into the filter situation and the only one that I can see that's suited to Brisbane LP, where it most street lights are Mercury vapour (M80 & M50), is the IDAS LPS-P2 - very exie! I did look at the spectral response of the Neodymium which is cheaper but it seems to let in a fair amount of Hg while hitting the Na.
Much better Mario! Colours look good and detail is better! You have a blue cast though, especially apparent in the background - check your histograms. They should be roughly aligned with no evidence of clipping. And lose that UHC filter!!
Ah nice Mario. There is some compression artefacts there, but the detail and colour look good.
Thanks Paul I use GIMP for final cosmetics which only deals in 8 bit images at the moment, although I do have a bodgie version of 2.9 which is supposed to handle 16 and 32 bit images. It might be worth a go through it...
Quote:
Originally Posted by marc4darkskies
Much better Mario! Colours look good and detail is better! You have a blue cast though, especially apparent in the background - check your histograms. They should be roughly aligned with no evidence of clipping. And lose that UHC filter!!
Cheers, Marcus
Thanks Marcus, it's good to be heading it the right direction! As for the blue cast, I'm hoping to add some more data to this to try and get a smoother, less noiser image, so I'll keep that in mind when I process all the data. As for losing the UHC filter - it's my Linus blanket!!! I can't imagine imaging from my backyard without it or some other type of LP filter...
Very nice work all the same Mario funny that you choosing to try dark sky tho mate ive just gone and picked up a LP Filter because Ive been inspired from your inner Brizzy's results ! !
Advantages both ways depending on how one looks at em
Cheers, , !
Colour looks good with nice detail and composition.
Ross.
Thanks Ross, I'm happpier with this effort and very happy in regards to the detail I've managed to get.
Quote:
Originally Posted by astronobob
Very nice work all the same Mario funny that you choosing to try dark sky tho mate ive just gone and picked up a LP Filter because Ive been inspired from your inner Brizzy's results ! !
Advantages both ways depending on how one looks at em
Cheers, , !
Bob, thanks for the compliments and I'm humbled that my images have inspired people to try new things! I guess the main problem I'm having are the red halos around the yellow stars. I feel it detracts from the overall image and is due to the missing green channel. However I've been reading up on creating a synthetic green channel based on Ha and OIII filters as this is, for all intensive purposes, what I'm dealing with using my UHC-S filter. If you look at the filter spectrum that I posted earlier you'll see the green dashed line (OIII) and the red dashed lines (Ha) are basically what the filter lets through.
As for the dark site, it's a bit like having a new car - it's nice to have one for the day to day stuff around the city, but every now and then you just want to get out on the open road and see what that baby can do (whilst always obeying the law)!
Colours look good and detail is better! You have a blue cast though, especially apparent in the background - check your histograms. They should be roughly aligned with no evidence of clipping. And lose that UHC filter!! 
ive just gone and picked up a LP Filter because Ive been inspired from your inner Brizzy's results ! ! 
