Thread: H alpha
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Old 02-11-2009, 10:19 PM
Hagar (Doug)
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Join Date: Oct 2006
Location: Australia
Posts: 4,646
Quote:
Originally Posted by Merlin66 View Post
I keep seeing this comment:
13 nm is a good choice particularly with a DSLR. It does allow the light frrom a lot more stars through than the 7nm

and for the life of me can't understand why this would ever be the case with Ha light????
The emission from Ha is a discrete line at 6563A.

Other than possibly some SII close by it doesn't matter one iota whether you view this single emission line with a 13nm or a 7nm filter. Other than the transmission efficiency of each filter, they will still pass Ha light??????
Perhaps you keep seeing comments like this because they are FACT, put down the theory and take a look, you might be surprised.
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