Quote:
Originally Posted by glend
Alex, you probably are well aware of this, but if not, you need to consider the f ratio change and how it impacts your narrowband filters. Standard narrowband filter sets are designed for a particular range of f ratio, and I believe very fast scopes like the RASA perform best with fast narrowband filters. I admit I Don't have all the facts, but I did contemplate converting my Celestron HD8 to Hyperstar at one point, and the advice I received on Cloudy Nights, was that I should go with the 'special' fast narrowband filters designed for RASA. It has to do with a shift in the filter spectrum band pass when you move from your f5,5 to f2. In other words you risk cutting out part of the very spectrum area your seeking to capture. It seems to be less of an issue where you have fairly wide spectrum narrowband filters, but is a big deal when your using narrow spectrum filters.
Info here:
https://www.baader-planetarium.com/e...iii-s-ii).html
Post #8 in this CN thread, has comparative examples,
https://www.cloudynights.com/topic/5...ters-for-rasa/ |
I think the filters I ordered take the RASAs needs into account.
Alex