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Old 02-10-2021, 08:31 AM

JA is offline
Join Date: Oct 2016
Location: Melbourne, Australia
Posts: 2,693
Originally Posted by Merlin66 View Post
Looking at the peak @ 6580A and assessing the FWHM (based on the visible curve in the blue wing) the 50% line seems to be at 6545A.
This would give a FWHM of 2 x 35A = 70A which is the Baader spec.
Thx Ken. So if the 50% transmission line passes through 6545A and knowing that the max transmission for this filter is probably around ~88-90% (from Baader literature for the 7nm CCD) that makes the Ha transmission not that great, around 65-70% very roughly.... Yes? If so, as an aside, that's quite a revelation, since when you look at the data when comparing filters, the graphs do not have such fine resolution and clearly could lead to the wrong impression of what represents a good filter for a particular application/ budget.


Last edited by JA; 02-10-2021 at 08:44 AM.
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