What is a blocking filter function?

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NightPhotographer
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What is a blocking filter function?

Post by NightPhotographer » Sat Aug 11, 2018 12:12 pm

I want to use my telephoto lenses for solar prominence imaging. I need to use front mount filters since rear mount filters mess with focus. Lunt offers front mount Etalon but I have difficulty finding a front mount blocking filter. Is there any other filter with the same function that can be mounted in front?
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rsfoto
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Re: What is a blocking filter function?

Post by rsfoto » Sat Aug 11, 2018 4:57 pm

Hi,

From my experience that will not work for H-alpha imaging. You need a blocking filter near the chip. So far have never seen a blocking filter right after an etalon.
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Merlin66
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Re: What is a blocking filter function?

Post by Merlin66 » Sat Aug 11, 2018 9:59 pm

The blocking filter is an extremely narrow band (10A) filter centred on Ha. This is mandatory with an etalon type filter to effectively "sort" the myriads of band passes obtained to just allow the one at Ha to pass through.

I think your application with the telelens may have to be re-assessed.
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marktownley
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Re: What is a blocking filter function?

Post by marktownley » Sun Aug 12, 2018 12:59 pm

The only way you could do it is with a camera Quark from Daystar, but even then I don't recommend a DSLR for solar imaging.
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