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Old 09-02-2019, 09:35 PM
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AstroJunk (Jonathan)
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Join Date: Jan 2006
Location: Moonee Beach
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It can be a matter of trial and error with eyepieces for Ha telescopes, and indeed, some lesser eyepieces can do very well.

You are looking at an incredibly narrow part of the spectrum at the, not surprisingly, red end! Normal eyepieces have coatings optimised around green, which is visually the most sensitive that our eyes detect so it is technically possible that specific coatings for Ha are brighter than generic coatings.

As chromatic aberrations become a non issue, simpler eyepieces like plossls can do very well, and with a centralised target, a 55 or less degree fov is just fine. My eyepiece case is dominated with Naglers for my dob, and these don't perform all that well in Ha. I very rarely deviate from the Lunt 7.2-21.5 (made by Orion in the US). I was told by either Andy Lunt or one of his engineers that the coatings were different from the std offering when they visited a few years back. I've not done a side by side comparison though.
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