So on a cloudy bright day an exposure for ASA 125 f/11 at 1/125 sec
yield 125 foot candles per square foot.
In a message dated 6/29/2007 5:44:24 P.M. Eastern Daylight Time,
elgenper@xxxxxxxxxxxx writes:
Andy,
unless I misunderstand you, it sounds as if you´re looking for
Ansel
Adams´ famous "Exposure Formula". Here it is, directly from
his book "The Negative": First compute the f/stop value
corresponding to the square root of the film speed in ASA (e.g., for
ASA 125, you get f/11).
Then, the luminance (in candles per square
foot) of a surface read by
a correctly calibrated exposure meter is
just the reciprocal of the
shutter speed for the above f/stop and
film speed.
I haven´t tried it in practice, but these are the words
direct from
the holy scriptures of St. Ansel himself, so they must
be true...
Good luck!
Per
|
