Just came across this. Can't believe I missed it. Great Lum you got in Ha. Amazing details. You've combined it with the color real nicely too.
Merci mate!!!
Admittedly the Ha is from a GRAS FSQ106 though!
The HaRGB combination is a difficult art to master I think - fun trying.
Ordered my 13nm Astronomik filter today So now I'll be able to fiddle to my heart's content!
Doug
Yeah Craig probably my dodgy processing - as to removing stars from the Ha hopefully one of the gurus will suggest something but I would try using the Colour Range tool to select the stars then Minimum filter to remove 'em to taste!
Any advance on that
That sounds like a good way to do it. Will give it a try.
Using 10minutes as a rough starting point for my proposed Ha exposures and using Eta as an example, would I be likely to record enough detail with the 6nm and 13nm filters in this time?
Doug
Hi Doug,
The usual advice on narrowband is to do longer than normal exposures so the signal gets well above the noise.
I have done 10 minute subs and they worked fine. 15-30 minutes may be better from a signal to noise ratio viewpoint.
It becomes more critical with O111 and especially S11 which si very dim.
Im about to drop a 12nm Ha EOS clip I got from Bintel into my modded 40D for a laugh, be interesting to see how it goes.
Even with a 90% QE Astrocam, 3nm needs long exposures, at least double the 15nm I had before, so I think that with a 40D would be marginal indeed, if not impossible. 3nm sure does bring out the detail tho , and cuts right through moon and sky glow, the background ADUs last night were only 120 (saturation at 65k) with 10min exposures.
I think the 13nm you want would be about as narrow as you can reasonably go, and youll be supprised at the results even with urban skies and moon, its the next best thing to dark skies..
Fred,
how did you go with the 12Nm clip in filter for the canon?
Well, here is M8 Ha about 10 off 5 min subs with ICNR.
The filter is fine, easy to put in and even live focus through on a bright star. But im having trouble processing the pic, needed a lot of stretching to get this far and noise is starting to show.
The raw data level is OK as far as I can tell, but its all quite different than a CCD pic to process, havent got my head round it yet, maybe need to use a dark library, more data or probably longer exposure subs.
Overall, it looks promising and Im certainly encauraged enough to perservere with it when the weather gets better.
Well, here is M8 Ha about 10 off 5 min subs with ICNR.
The filter is fine, easy to put in and even live focus through on a bright star. But im having trouble processing the pic, needed a lot of stretching to get this far and noise is starting to show.
The raw data level is OK as far as I can tell, but its all quite different than a CCD pic to process, havent got my head round it yet, maybe need to use a dark library, more data or probably longer exposure subs.
Overall, it looks promising and Im certainly encauraged enough to perservere with it when the weather gets better.
what was the ISO? Maybe because of the bayer matrix double the time might be needed? its not a cooled 40D is it?
1600ISO, I figure a lower ISO just lowers gain needing longer exposures and then more thermal noise pops out. I posted in a previous reply I saw data in the GB channels, until I found the Ha filter wasnt in, very annoying, now there is next to nothing in GB (makes sense now).
No its not cooled, im not looking to try that mod myself again.
I processed all the subs as default RGB in IP (saved as FIT) until PS import with fits liberator, with which I just selected pane 1 (red).
I think everythings OK, I just need to try some other stuff, this pic was just a guess. It took me a while to get going with a CCD, so Im expecting the same with the 40D. Ive done all this before with a 300D, but not with Ha, I just need to tweak a few things.
Focus looks pretty good to me Doug, and good detail generally too.
The middle is blown out a bit thogh, lost detail there altogether, but shows more in RGB. Have another go on the Ha without streching the middle so much.
