Thoughts on this system for refractor or sct imaging?
https://beloptik.de/en/h-alpha-system-2/
Beloptik ha system
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Re: Beloptik ha system
Personally, no. Lots of people on here have tried the telecentric / air spaced etalon route and it yields results with too wide a bandpass.
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Re: Beloptik ha system
"Personally, no. Lots of people on here have tried the telecentric / air spaced etalon route and it yields results with too wide a bandpass."
I would expect that, since 0.7 angstrom air spaced etaons were originally intended for use on the front objective, where the 0.25 degree field angle of the Sun's limb represents about f108, and I doubt many of the telecentric systems have been employed at that effective f ratio for these small air spaced etalons. Air spaced etalons will to do better with collimator based systems vs. telecentric. The problem then becomes the size of the etalon, the need for similar f ratios for the collimating optics, and focal length/field angle magnifications that don't create too small a Jacquinot spot.
As a general rule telecentrics are better for smaller solid spaced etalons, and collimators are better for the relatively larger air spaced etalons.
I would expect that, since 0.7 angstrom air spaced etaons were originally intended for use on the front objective, where the 0.25 degree field angle of the Sun's limb represents about f108, and I doubt many of the telecentric systems have been employed at that effective f ratio for these small air spaced etalons. Air spaced etalons will to do better with collimator based systems vs. telecentric. The problem then becomes the size of the etalon, the need for similar f ratios for the collimating optics, and focal length/field angle magnifications that don't create too small a Jacquinot spot.
As a general rule telecentrics are better for smaller solid spaced etalons, and collimators are better for the relatively larger air spaced etalons.
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