What does a blocking filter do?

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
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NightPhotographer
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What does a blocking filter do?

Post by NightPhotographer » Mon May 16, 2016 11:16 am

What is the function of the blocking filter in a solar telescope?

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robert
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Re: What does a blocking filter do?

Post by robert » Mon May 16, 2016 11:23 am

Selects a narrow band of light around the Ha line of the spectrum and rejects the multiple very narrow bands that are filtered by the etalon which can described as a comb filter. Essential part of the scope. Without it the view is swamped by many narrow bands (on either side of the Ha line) getting through, sort of harmonics or resonances of the etalon spacing.
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images and animations http://tinyurl.com/h5bgoso
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NightPhotographer
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Re: What does a blocking filter do?

Post by NightPhotographer » Mon May 16, 2016 4:26 pm

is there a front fitted version of it? All I could find were rear fitted ones.

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robert
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Re: What does a blocking filter do?

Post by robert » Mon May 16, 2016 6:55 pm

No it is in the converging light cone at the back end. The etalon has to have parallel rays to work so is on the front end
R
images and animations http://tinyurl.com/h5bgoso
2018 images https://www.flickr.com/photos/69734017@ ... 1234171714
2017 images http://tinyurl.com/gvk9k3k
ED80. SW200. Celestron-150mm-PST mod
LS60PT-LS60F-B1200. B600-Cak. PGR-Ch3-IMX265


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