...I just want to make sure I don't have any signs of sanity!
While much of what I'm about to write has been said already, I'll recap so I hope everything is here.
My goal: take nice looking night sky photos, emphasis on deep sky/wider angle stuff using normal lenses.
Main kit: Astrotrac TT320X-AG to do the tracking. 450D and 7D with cable release. Astronomik CLS
EOS clip filter. Assorted lenses.
To do: 450D converted for astro use (~2 stops benefit at H-alpha).
My biggest problem: light pollution
The CLS filter seems quite effective at removing sodium and mercury lighting pollution, but I suspect there are a lot of other broad band light sources which it wont really help with. I'm debating if their UHC filter will help, since that is narrower passband.
The issue here is what subjects am I going for? The CLS and UHC filters primarily pass emission nebula spectral lines, so will provide the greatest benefit there. Someone linked to an article claiming there wasn't any benefit for broad light source subjects, but I think they will although to a much lesser degree. While it will cut out significant parts of broad band sources, it will still cut out proportionately more of the narrowband interference.
Further thought, is there a benefit to stacking filters here? Logically I think the answer is yes... now I can only fit one in the body, but I can get a lens front one too in addition, although I am a bit concerned about filter reflection effects here.
Taking that to an extreme, should I even consider doing narrowband capture? On that note, is there a simple list somewhere saying what objects emit what stuff? Obviously if I go this route I think it would very much force me to focus on emission nebulae. That's ok, as they're the more easily pretty objects out there.
So on filters, the questions are:
1, would switching from existing CLS to UHC be much benefit?
2, would stacking a UHC with existing CLS provide even more benefit?
3, should I consider narrowband imaging?
There is one other option, but being realistic, I'm not sure it will be a practical one. Go somewhere darker! Trouble is, I have a day job. So I don't have much time on weekday evenings and weekends aren't much better for me to go out somewhere else. I doubt I can get anywhere much better within 30 minutes travel time.