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Old 22-03-2012, 09:55 PM
Poita (Peter)
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Join Date: Jun 2011
Location: NSW Country
Posts: 3,585
Originally Posted by RickS View Post
I wonder if it depends on the object you're imaging? If it's something which emits a lot of Ha then you wouldn't expect to see much difference in exposure time between a 3nm and a 5nm Ha filter. If it emits more evenly across a broad spectrum then perhaps you get a significant amount of additional light through the wider 5nm window?

I have both 3nm and 5nm narrowband filter sets but I've never really spent time comparing them. Perhaps one moonlit night I'll give it a go. Assuming the sky ever clears...

That makes perfect sense, many objects I view with it are not purely Ha so to speak.
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