If the eclipse is not complete or during the partial phases of a total one you
are essentially directly photographing the sun. During totality things get quite
dark and colorful around the moon with "tonges" of reddish protuberances like a
crown of flames surrounding it. During this phase color film is useful. The
corona is a more wispy phenomenon but it varies in brightness from center out so
bracketing exposures is common. A filter that removes light and IR from the
scene during partial phase is useful so as not to overexpose. In my opinion
there is not much difference between a photograph of the sun's disk taken
through an IR transmitting, light blocking, filter as opposed to one taken
without so I guess I'd use the IR filter as an light energy reducing filter -
problem with the IR filter is you lose all visibility through the camera. An IR
filter might look safe to look through at the sun but DO NOT DO IT as it still
transmits copious amounts of IR and this can damage eyes. Use a sunlight
blocking filter that removes IR and light and UV from the light from the sun.
There are lots of websites with instructions on how to deal with a solar eclipse
including PhotoForum's own FAQ files located at:
http://www.rit.edu/~andpph/pf-faq.html
The actual text for this is found in Section 36 - note 04 and it goes like this:
================================================================================
Note 36.04 -< Photographing a total solar eclipse >-
--------------------------------------------------------------------------------
>There will be a full eclipse of the sun in Thailand on Oct 24. I want to take
>eclipse photographs but I'm not prepared. As I know the aperture must be kept
>constant and the shutter speed changed while taking picture. Before totality
>a ND 400 filter is required. What material can I use as ND filter ?
You can still make a test for the uneclipsed pictures by simply photographing
the full disc of the sun this week. Your statement about using f11 (probably
with 100 speed film) and a ND 4.0 filter is reasonable IMO and you'll probably
be using a shutter speed of something like 1/500 second.
Note that the ND filter is 4.0 and not 400 - 4.0 means that 1/10,000 of the
light falling on the filter makes it through BUT BEWARE OF THE Infrared that
gets through in much larger and invisible quantities ... if you get a
photographic quality gelatin ND filter DO NOT use this filter to look at the
sun with ... use itONLY in front of camera lens and then looking at image on
camera viewfinder is generally safe. When totality happens the filter is
removed from the lens.
Negative film is more forgiving in terms of exposure but you can't beat the
brilliance of a transparency in terms separating the fiery red prominences
from the corona and reproducing the pearly white outer corona which is visible
and should be evident in the pictures receiving fuller exposures.
>Is a 300 mm lens too small for this?
No. A 300mm lens will give you an image of the sun which is about 3mm on the
film or about 1/10 the size of any full frame enlargement made from the film.
In fact interesting photographs of the partial stages of the eclipse can be
made with much shorter lenses. For example you could use a 50mm lens and then
take several photographs on the same frame (with multiple exposure) showing the
several stages in the approach and receding stages at either side of a frame
showing the full eclipse. Pictures like this are common but in spite of the
fact that I've seen two eclipses I don't have one (and it is one I dearly would
like to have made!)
>For instance Before full eclips, using f11 meter light by camera meter and
>speed is 1/125. I must do a compensate using 1/125, 1/60, 1/30 , 1/250, 1/500
>and 1/1000, is this right?
I don't think that bracketing during the partial stages does anything other
than waste good film. If you wanted to assemble a "series" or make a flipbook
or such I would spend the film on making many exposures rather than bracketing
wildly. Making a test beforehand (as suggested above) would still be a good
thing to do to reduce the need for bracketing.
>When eclips is full, take off ND filter, use f11 and take photo with all
>shutter speed, is this right? Any more suggestion would be appreciate,
Well, I think that exposures in the 1/250 - 1/1000 second area are really too
short during totality. You will probably want to bracket from 1/60 second to
about a second or so. Due to the small size of the sun it will be impractical
to make a light meter reading either during partial or total stages. Exposure
times beyond 1 second may exhibit significant blur due to rotation of earth. I
would suggest you open up a stop or two if you are trying to get an extended
picture of the corona.
You may have difficulty getting a ND 4.0 filter in your location. There are
Mylar filters that will probably be sold in your area to view the partial
stages. If I recall correctly these can be also used for photography. BTW ...
use a good tripod and tape the lens barrel so that you don't change the
position of the lens from infinity focus.
finally ... here is a wish that you have a nice clear sky!
andy, andpph@xxxxxxx
trevor cunningham wrote:
Tomorrow is a scheduled total solar eclipse whose path passes through Egypt, but not Cairo. It's passing through a small town called Saloum on the border with Lybia at the NW corner of the country. I'm trying to get a perspective as to the totality of the eclipse that I will experience...also, would an IR filter be useful in capturing such an event?
"The optimist believes this is the best of all possible worlds.
The pessimist fears it's true" - J Robert Oppenheimer
http://www.geocities.com/tr_cunningham
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