First Narrow Band tonight -hopefully

[glend (Glen)]

I am setup in the Obs to start my first steps into narrow band imaging tonight. Yeah, could have picked a better night, I know it's the full moon, but my reading says this is ok as long as I stay with a target that is in a different part of the sky to the moon, the more separation angle the better. So I am thinking of Eta Carinae, which I have shot alot in broadband, and it (the moon) will be about 180 degrees away from the front of the scope. I am planning on using my MN190 simply because it is relatively fast (f5.3) and it has excellent tube baffling. I will also stick a light shield on the front of it. I'll be sticking with Ha tonight I think, maybe some SII but no OIII because of the moon.
My filters are the Baader Narrow Band set (36mm unmounted) which will be going in my Canon EOS filter drawer. The camera is my Mono Cooled Canon 450D and I am looking forward to testing it out with narrow band filters. Any advice on sub lengths? I have no idea when it comes to narrow band sub lengths. I was just going to start with 300" and work up from there. I know I will need them to be long, but how long? I hope I can hang on to a guidestar with my broadband guidescope in the light pollution from the moon.
Anything else I should know in advance?
Thanks

[vlazg (George)]

Good luck for tonight, i will be going down the same track in about 4wks so i will be interested in your outcome.
Sorry can't help with sub lengths but i know the o3 and s2 will be longer compared to the Ha.

George

[Atmos (Colin)]

As for the sub length, it all depends on what your camera has for read noise. For my QHY9 optimal exposure time was about 2 hours with 8.5e- read noise. With my newly acquired QHY22 (arrived yesterday) it should be about 35 minutes but I really need to do some calculations tonight as it has a read noise of 4.5-5 e-.

Also have to take pixel size and QE also get taken into account.

[Camelopardalis (Dunk)]

Glen, crank the ISO up to 1600 and expose until the main peak (the background sky) is about 20-25% from the left.

[glend (Glen)]

Thanks Dunk. Unfortunately the high cloud stopped any activity last night. I will try again when possible. Of course It's perfectly clear this morning - typical.

[glend (Glen)]

I was finally able to complete a test run in Ha last night. I have put the details of the test in my Mono Camera Build thread here:

http://www.iceinspace.com.au/forum/s...82#post1238682

and the short stack of subs (8*300") have given me this image posted in my Astrobin gallery:

http://www.astrobin.com/full/243048/0/

The results are encouraging, and clearly dithering and DSS have eliminated the sensor artifacts that were troubling me. Looking forward to more clear nights to work on narrowband.

[Atmos (Colin)]

There is a fair bit showing up for just 300s, going longer will allow a lot more of the fainter nebulosity to pop out from the background