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Old 26-03-2021, 12:49 AM
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Don Pensack
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Don Pensack is offline
 
Join Date: Aug 2006
Location: Los Angeles
Posts: 508
Yes, the Astronomik O-III is a 2-line filter which passes the 495.9 and 500.7nm lines at a high %, where the Baader O-III is a 1-line filter that only passes the 500.7nm line and at a slightly lower % transmission.
The Baader is a decent filter for imaging, but it cuts too much light for the best visual image.
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