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Solar filter for C9.25 HD


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I think Celestron used to produce a filter for this size scope but no longer does.  Does anyone know of a manufacturer that produces a solar filter for this size aperture?

NOTE: Please, please don't tell me to DIY one.  I can barely put together IKEA furniture 😂

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The Baader film filters are the best of the front mounted solar filters. The problem with glass filters is proper optically flat glass is so expensive it’s not used in any of the glass filters.  Funnily enough the glass filters scratch easily so not as long lasting as you might think.

Edited by johninderby
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5 minutes ago, johninderby said:

The Baader film filters are the best of the front mounted solar filters. The problem with glass filters is proper optically flat glass is so expensive it’s not used in any of the glass filters.  Funnily enough the glass filters scratch easily so not as long lasting as you might think.

Interesting you say that, the Thousand Oaks website says their filters will not break or scratch...false advertising?

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The Thousand Oaks glass filter are one of the best glass filters around and many do like them. The Baader film gives a brighter image though so the use of a variable polarising filter is recommended to allow you to adjust brightness to give the maximum detail depending on the seeing conditions. The Baader film is surprisingly tough.

I have seen glass filters with scratches though so not sure if this is absolutely true.

A solar continuum filter is recommended to give that last bit of detail.

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For large diameter scopes like the C9.25, solar film filters are probably the best solution. Light, cheap and more than good enough.

Baader and Astrozap offer various models and diameters suitable. Their respective designs are a bit different, you decide what's best for your needs:

https://www.highpointscientific.com/astrozap-baader-solar-filter-for-9-25-quot-sct-and-259-mm-269-mm-telescopes-az1005

https://www.harrisontelescopes.co.uk/acatalog/baader-solar-filter-for-9.25-sct-telescopes.html

(note: the Baader filter needs a bit of assembly, the Astrozap is more ready-to-run as far as I know)

N.F.

 

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