8mm Forum: Filming the Sun

This is topic Filming the Sun in forum 8mm Forum at 8mm Forum.

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Posted by Benjamin George Smith (Member # 3059) on June 01, 2012, 08:24 PM:

As bizarre a question as it may sound, I would really love to know what sort of filter would be recommended for filming the Transit of Venus as it passes in front of the sun.

I have a Canon Zoom 518 and new Tri-X and 100D cartridges to test it out with!

Posted by Maurizio Di Cintio (Member # 144) on June 02, 2012, 02:58 AM:

Personally I'd use a camera with a longer focal length in order to magnify such smalla detail as Venus as much as possble.

Anyway given the huge amount of light you are going to shoot with and the relatively high speed of the film you are going to use, I'd reccommend you use a very dark grey filter (at least ND 4x) so that you prevent your camera from using too close aperture on the iris which tends to create dffraction: a lens usually delivers the best performances it's capable of when used in the mid - aperture range, say F 5.6-8.

I would avoid the Tri-x for this reason. Should the ND filter not suffice for this purpose, I'd screw on an additional polarizer (preferably a circular one, as linear pola may deceive the built-in photocell to a 'devastating' degree). Even better you might want to use two polarizers which can be set in such a way to let a very small amount of light reach the film. I think this is a very sensible and convenient (though a little expensive) way to shoot such a subject.

Also a steady tripod is a must. Perhaps you migh try some time lap frame interval shooting if your camera allows for it and for manual exposure.

One preacaution: avoid pointing the camera directly against the sun prior to mounting some darkening filter on the lens: the photocell might be damaged (and your eye harmed).
I think that's pretty much all the things you need to pay particlar attention to.

Good luck.

Posted by Hugh Thompson Scott (Member # 2922) on June 02, 2012, 03:56 PM:

Please be very very careful on anything that involves lenses and
the Sun,damage to your retinas is irreversible and caution should be exercised.

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