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Re: (IAAC) Orion Natrium Filter



The filter that Yann is referring to is a broadband filter made by Orion
Optics UK and from my brief look at one of the early ones is a complete
waste of money. Their EHC filter is not too bad. Natrium as you suggested
is a corruption of the latin for sodium. Stear well away from this one Yann
At 15:06 28/05/98 -0400, you wrote:
>
>Oops - come to think of it, it's more likely these "Natrium" filters BLOCK 
>sodium than narrowly bandpass it... After all, at least in the US, much of
the 
>artificial skyglow derives from sodium-vapor (Na emission) lighting. Is it 
>possible that "Natrium" is Orion's European name for their "Ultrablock"
filter 
>(similar to the Lumicon "UHC" filter)?
>
>Lew, awash in emission lines
>
>
>
>

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