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The Coronado and Lunt blockers are not identical in bandwidth, CWL (central wavelength) or transmission.
The blocker bandwidth and CWL depends very much on the bandwidth and finesse of the etalon - they should be matched to minimise off band leakage.
I found similar differences when using a Lunt blocker on my SM60 set-up, but in my case it was a brighter (!!) image. I eventually traced the "issue" to a failed ITF in the Coronado. Once this was replaced the image from the Coronado blocker was as bright (if not marginally better) than the Lunt.
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