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Re: [OM] Solar eclipse advice

Subject: Re: [OM] Solar eclipse advice
From: Roger Wesson <roger@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Mon, 10 Jun 2002 15:30:47 +0100
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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