From: Jason Halprin (email suppressed)
Date: Tue Nov 02 2010 - 05:03:06 PDT
Well...Long story short, a very long exposure of months or years would be very
difficult or nearly impossible to meter for. When you meter for a shot you are
basing the characteristics of the film on the straight-line portion of the
characteristic curve - meaning that the film has a more-or-less linear
relationship between exposure and density.
If you were to expose for months, you would be exposing in the "shoulder" area
of the curve, that area where an increase in exposure results in an ever
decreasing ratio of exposure to density. Essentially, you are working with a
situation where most of the possible silver-halide has been activated, and the
film no longer has linear, predictable results.
Now that that's out of the way, I would propose making your own pin-hole
aperture (f64 ? smaller?) and centering this on the back of the lens to lower
the amount of light getting to the lens. Also, use a very slow film...and test,
test, test. Don't expect a doubling of exposure time to result in a stop of
increase in density (it won't be nearly that much). It would seem the easiest
option would be to rig a cable release on an SLR camera so that you can leave it
open, on a tripod, for a very long time...vary your exposure, and take good
notes.
-Jason Halprin
________________________________
From: Aditya Mandayam <email suppressed>
To: email suppressed
Sent: Tue, November 2, 2010 6:40:11 AM
Subject: [Frameworks] Extremely Long Exposures - for Months and Years
Hello, I am interested in making extremely long exposures: of the
order of many months, perhaps a few years.
E.g: http://photoslaves.com/open-shutter-by-michael-wesely/
I asked this question on photo.net as well:
http://photo.net/black-and-white-photo-film-processing-forum/00XKLr
I would like to know how to meter for such long exposures. What amount
of light does one assume? Average brightness of a day over a year?
Thank you.
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