Transmission of a polarizer is varying depending on the rotational position in the lightpath as well due to added polarizing effects of the imaging optics itself. We do not have info on transmission values sorry to say.
Traditionally the glass-embedded polarising plastic-film inside any such filter will only transmit sufficiently in the range from 400 to 700 nm. We have no information within our field of amateur astronomy about poarisers covering the UV – nor UV and VIS together.
Concluding we think that using our (nor other common) polarizers for your intended purpose would not at all yield satisfying results.
Answer by: Baader Web Team (Admin) on Feb 19, 2024 7:08:00 AM
I believe I fully understand the requirement for a telecentric lens system for H-alpha observation. A point of confusion remains the selection of the appropriate multiplier factor for my telescope. I have an f10 instrument, so I believe you will recommend a 3x factor to achieve f30. What confuses me is why would not a 2x factor suffice, or even 1x? As long as the output beam is parallel light, I should have identical viewing across my etalon. Is the reason the 0.5 degree diameter of the sun itself, which still creates a tiny amount of tilt of rays coming from the limb of the sun relative to the parallel rays coming from the center?
Unfortunately, it would go beyond the scope of an answer to a product inquiry to provide a detailed physical explanation of the necessity of f/30 for etalon filters. However, it is a fact that this is the prerequisite for creating contrast in Halpha, especially on the surface of the sun. Even with f/2 or f/1 telecentric systems, which can indeed be produced, an f/30 beam path must be created at the end
Answer by: Baader Web Team (Admin) on Feb 16, 2024 2:13:00 PM
At telescopes faster that f/10, we always recommend a glasspath corrector - at such a fast telescope, the prisma inside of the binoviewer can introduce colour aberrations, which are removed by using a gpc. You also risk vignetting by the focuser if you add a binoviewer, which needs ca. 11cm of back focus.
Answer by: Baader Web Team (Admin) on Feb 14, 2024 10:06:00 AM
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