2" CaK ERF??

Frankenscope? Let's see it!***be advised that NOTHING in this forum has been safety tested and you are reading and using these posts at your own peril. blah, blah, blah... dont mess around with your eyesight when it comes to solar astronomy. Use appropriate filtration at all times...
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PEterW
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2" CaK ERF??

Post by PEterW » Sun May 13, 2012 9:19 am

Anyone know of a CaK ERF in 2" threaded format.... I got ideas!

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PEter

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Merlin66
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Re: 2" CaK ERF??

Post by Merlin66 » Sun May 13, 2012 9:24 am

I think Bob was advocating a Baader Blue ex- RGB CCD set..these would be available in the 2" filter thread.....
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Re: 2" CaK ERF??

Post by marktownley » Sun May 13, 2012 10:13 am

Thats the one to go for Peter ;)
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Re: 2" CaK ERF??

Post by PEterW » Fri May 25, 2012 7:10 pm

Hoya b390 glass, nearly perfect. Can get it cut to size, cheaper than special B filters.

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Re: 2" CaK ERF??

Post by marktownley » Fri May 25, 2012 8:23 pm

Hoya b390 glass, nearly perfect. Can get it cut to size, cheaper than special B filters.

Any sources for it?
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Re: 2" CaK ERF??

Post by PEterW » Fri May 25, 2012 8:54 pm

http://www.hoyaopticalfilters.co.uk/ need to ask for a quote for a 2" bit. optical quality probably worse than a dedicated B filter, need to check my scope will come to focus before I buy one.

Peter

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Re: 2" CaK ERF??

Post by colinsk » Sat May 26, 2012 1:38 am

I am told that glass for CaK filters has stresses and bubbles. I am by no means an expert in this. If you find a piece of glass make sure to examine it through crossed polarizers before polishing. You may be able to re-anneal it if it has stress.

Edit: I should say for Cak ERFs....
Thank you, Here are some references I have collected.



Etalon Article Part I

Etalon Article Part II

Solar Patents of interest

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