I'll second the recommendation of the Thousand Oaks film. I used it to
fashion a filter for my Astrotech AT80 for the 2004 solar transit of Venus.
Works very well and I still have all my rods & cones. Looking forward to
same in 2012.
Charlie
On Wed, Feb 3, 2010 at 8:11 AM, Carlos J. Santisteban <zuiko21@xxxxxxxxx>wrote:
> Hi Piers and all,
>
> From: "Piers Hemy" <piers@xxxxxxxx>
> >But if you insist on pointing optical equipment at the sun, I can
> recommend
> >the products of Thousand Oaks Optical
> >
> ><http://preview.tinyurl.com/2y7cj>
>
> I contacted them for the solar eclipse of 1999, but they wouldn't provide
> the filter in time, so I made my own homebrewed filters -- a roll of
> 120-format Ilford Pan-F strongly developed in an open tank. The 120 film
> did
> not cover completely the Tamron 500mm, but with the help of a mask
> everything went well.
>
> I eventually made two different versions: one lighter (ND 4.0) for picture
> taking (later used with the Zuiko 300/4.5 and other lenses) and a stronger
> one (ND 6.5 approx.) for direct, safe observation -- I keep one of these in
> my wallet, just in case.
>
> Other films may have a frosted base, and thus not suitable. And colour film
> (or chromogenic B&W) is strctly forbidden -- it won't block IR!
>
> A few pics of the filters in use:
> <http://cjss.sytes.net/etc/IMG_0157.JPG>
> <http://cjss.sytes.net/etc/IMG_0158.JPG>
>
> And some pics _thru_ the filters:
> <http://cjss.sytes.net/etc/transito/> (The transit of Venus in front of
> the
> Sun -- excuse the extremely dirty sensor...)
>
> It seems to impair sharpness, though :-(
>
> Cheers,
> --
> Carlos J. Santisteban Salinas
> IES Turaniana (Roquetas de Mar, Almeria)
> <http://cjss.sytes.net/>
> --
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>
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