If the weather is clear I fear you might have difficulty getting the
exposure right - you really need a solar filter which reduces the light
intensity by a factor of 10^5, or 16.6 stops. Stacking four ND4 filters
would give you roughly the right level of filtration but image quality
may end up very poor. I've heard that welder's masks are also
sufficiently dense to make solar viewing safe. If you have the right
amount of filtration it's a good idea to bracket quite a lot - 1/1000 at
f/8 is a good starting point. No matter how much of the sun is
obscured, the exposure is still the same, so for future reference you
might want to try some test exposures on any clear day.
Things may be a lot easier if it's cloudy - here's a shot I got in
Cornwall, 1999, before the clouds thickened and obscured the whole of
totality:
http://www.worldtraveller.f9.co.uk/astro/photos/eclipse/pictures/eclipse3.jpg
No filters on the front, I just took a meter reading from the whole scene.
An alternative technique if you haven't got the filters is to photograph
reflections of the sun in water. Here's an example from Zambia almost
one year ago:
http://www.worldtraveller.f9.co.uk/travel/zambia-malawi/morephotos/photos/eclipse/Partial
0.000000e+00clipse,%20reflected 0n%20the%20Zambezi.jpg
As far as eye damage goes, it won't do any lasting damage to take quick
glances through the viewfinder to check composition if you haven't got
any filters on. Filters will mean it won't cause you instant harm to
look at the sun, but don't look for too long even then - some filters
might not screen enough UV light, which could do some damage. Mylar,
which comes in sheets, is safe for photographic and visual observing.
Hope that helps, and I hope the weather's good for it!
Roger
NSURIT@xxxxxxx wrote:
At sundown today their will be a partial solar eclipse and Houston will
be one of the areas where it can best be seen. As a guy with a camera,
I almost feel obligated to try to capture the event. I would be
interested in opinions on how to safely capture it. My initial idea
(keeping in mind I don't want to fry my eye) was to use the 200mm f4
with ISO 200 film and stack some combination of a graduated ND,
Polarizer & ND 4. Plan is to focus on infinity and then wait for the sun
to get where I want it to be and minimize my looking thru the camera
when the sun is actually in the picture. Any thoughts? Bill Barber
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