NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: EBBCO/filters
From: Peter Fogg
Date: 2007 Nov 22, 15:41 +1100
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From: Peter Fogg
Date: 2007 Nov 22, 15:41 +1100
Peter Fogg wrote:
> Hmm. My understanding is that a thin sheet of plain old ordinary transparent
> glass is quite an effective UV filter - and that UV filters made for use in
> front of camera lenses consist of little (if anything) else!
and Michael Daly responded:
I don't know that that's a safe assumption. Plain glass absorbs higher
energy UV well, but not lower energy. Given that blue light can do as
much damage to the retina as low energy UV, I'd only recommend a
certified, high-absorption UV filter material.
Well Mike, let's all hope that sextant manufacturers have taken your advice to heart when making their filters. I have doubts about that, given what generally low quality scopes they attach to the things. I suspect they go for sufficient neutral (more or less neutral, that is) density and that's that. To expect more could be unrealistic.
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