I’ve come up with this test report of Optolong and ZWO filters not only because we are the main Optolong importers and ZWO distributor in the UK, but because I myself also wanted to see what we sell and whether we should expect any problems, which is of course very important if one wanted happy customers… It was also a response to an article I read on the Cloudy Nights forum: https://www.cloudynights.com/topic/602155-testing-optolong-and-baader-narrow-band-ha-sii-filter/… Read more »