P3D Re: Photographing the Eclipse

[Brian Reynolds <reynolds@xxxxxxxxx>]

Peter Homer wrote:
>  This time it is at a better time of the year and if the present good
> weather continues we are going to have much better but potentialy hazardous
> viewing conditions. What sort of filter (if any) can I use to protect my
> eyes and prevent overexposure of the film. There have been a number of
> filters for sale for viewing the eclipse including ones with BSA kite mark
> but they seem to be advising not to use these even ,just the projection
> method. One of the things I want to try is to use a pair from the sequence
> to produce a stereo pair using the movement of the sun and moon to show
> that they are not in the same plane but that the sun is 400 times as far a
> way as the moon.    P.J.Homer
> 
> 

At Sky & Telescope's web page <URL:http://www.skypub.com> you'll find
information about eclipse viewing and an online copy of the solar
filter review that ran in a recent issue.  Click on Sights and then
Eclipses to get to the generic (not centered on North American views
of this particular eclipse) eclipse information.

Be very careful about viewing an eclipse through any optical device.
You always want a filter IN FRONT OF THE OBJECTIVE.  Many older
telescopes came with a filter that screwed into the eyepiece.  The
telescopes objective would focus the sun's energy on this filter and
it would eventually crack, sending pieces of glass and unfiltered,
focused sun light into your eye.

I used to have a Tuthill Solar Skreen for a Celestron C-90 (I've sold
the telescope and filter).  It produced nice views, and some good
pictures of the last partial solar eclipse in the New York City area.
Tuthill <URL:http://www.tuthillscopes.com/> used to give out samples
of Solar Skreen, and sells eclipse viewing glasses that look like card
board anaglyph or polarized glasses, except that they use Solar
Skreen.

By the way, Solar Skreen looks like the stuff that Pop Tarts are
wrapped in, but it is different.  Although Solar Skreen is aluminized
Mylar, it is aluminized on both sides, manufactured to a specific
thickness and inspected for pinholes.  It is not safe to use ordinary
pieces of mylar as a solar filter.

Welder's glass in the 12-14 range is considered safe, with 13 and 14
being more comfortable to view with.

You can probably find more local information at the web sites of one
of the British astronomy magazines, but I don't know any of their
URLs.  You might also want to check at the local planetarium or
science museum.  They will hopefully be selling the proper viewing
filters.  This late in the game it might be hard to get a camera
filter, but check the local astronomy shops.

-- 
Brian Reynolds                  | "Dee Dee!  Don't touch that button!"
reynolds@xxxxxxxxx              | "Oooh!"
http://www.panix.com/~reynolds  |    -- Dexter and Dee Dee
NAR# 54438                      |       "Dexter's Laboratory"


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