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Acquiring mono RGB data over the city

06 Aug, 2019 23:23
Total newbie here.  I have a mono camera and a filter wheel.  First light was an underexposed OIII stack of M 16, 3 days ago.  Well, first light was actually 90 minutes of Ha  the day before, but so out of focus to be useless!  ooops.

I have the advantage of shooting over the ocean (to the south) for most of my targets, so the city isn't an issue.

I put shooting the Veil on my to-do list..  I was thinking Ha, OIII, and then an RGB set for the stars.  Is there a trick to getting the stars when shooting over the light polluted city?

I know the NB filters are ok, but how does one deal with 100nm wide filters over Los Angeles??  I do not have a light pollution filter so I assume I need a trick to get the SNR way up.
09 Aug, 2019 09:28
I live in the suburbs of London, and find LP a real pain.  However I have achieved a fair bit with narrowband and in the early days with a DSLR, mainly the brighter targets.  I tried last year to add RGB stars to NB images, and it does seem to work OK.

I made up a personal website of images I have achieved for Bortle 8, this may give you some idea:

Plus I don't have an ocean to the south of me.  Only more town and LP.

Re LP filter, of course you could get one, I have one but I often forget to use it and I don't think a LP filter was used on all the Mono shots on the website above.

Hope this helps

Edited 09 Aug, 2019 09:32
11 Aug, 2019 18:53
My "trick" (used by almost all serious imagers) is gradient reduction in processing.  It's surprisingly effective.  Example.  RGB data.  No other processing besides a simple stretch, necessary so you can see the linear data.

Red Zone, Bortle 7, mag per arc sec squared low 18s.  You do need to do the total imaging time, this was 164X30" at F4.8.

Final image with H alpha added, giving the acquisition details.
Edited 11 Aug, 2019 19:04
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