NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: EBBCO/filters
From: Mike L
Date: 2007 Nov 21, 03:47 -0800
From: Mike L
Date: 2007 Nov 21, 03:47 -0800
Hi peter, I tried searching and couldn't find the posts. My concern with using two polarising filters is that the UV may behave differently and not be polarised, so although the optical light is diminished, the UV comes through just as before! One solution I'm considering is using solar filters for astronomy and I quote (http://www.greenwich-observatory.co.uk/acatalog/ Solar_Filte.html): "BAADER AstroSolar film has become the natural first choice for white-light solar observation. It's optical qualities are excellent, enabling you to see high-resolution images with a natural colour." Only problem is that it doesn't say how much the light is attenuated and although it ought to be suitable, I've no way of checking out before hand. The other alternative I'm considering is buying some sheets of optical filters - unfortunately with no guarantee on UV transmission so only for lunar work (is there any significant UV in moonlight?). Mike On Nov 21, 8:10 am, "Peter Fogg"wrote: > Greg R > > Check out the List archives for discussion on using polarising filters. If > you use two in series they can be rotated for increasing combined density, > right up to total. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---