On Fri, 31 Jul 1998, Dan Lau wrote:
> Now I am a little confused by the "terminology". If your hand is 1 stop
> "brighter" than 18 0rey, then shouldn't you "close" down one stop to
> compensate (i.e., get back to the 18 0rey measurement) instead of "open"
> up one stop? It seems to me that if you measure against your hand which
> is 1 stop brighter AND you open up one stop from that measurement, you
> will be over exposing (by 2 stops).
No, and here's why. The hand's tones values are interpreted into a
reading by the meter that reads 18 0ray, but the hand,in effect, is +1
f/stops brighter than that, so the meter's suggestion would put the hand
at 18 0ray, which is -1 f/stop from its tonal value
(as opposed to the 18 ard). Foxy simply gives it a +1 correction
so as to get back to the 18%, and thus have an accurate idea of the
intensity of the light falling on the scene. It is imperative that when
you do this "hand-jive" metering, that the light falling on your hand be
the same that is falling on the subject. You do not have to walk up,
the sun's 93 million miles away, a few feet or hundred miles, for that
matter, won't make much of a difference. The angle of your hand is also
important, and must resemble the surface plane of your subject in relation
to the light. The surface of your hand must also fill the frame when you
take your reading, unless you're spot metering off of it. This works for
backlit subjects or those in shade.
A hand-held meter's more convenient, IMHO, but this works.
Do not assume all hands are equally reflective. Buy or borrow an 18 ard
and calibrate your hand, so you know what the correction is.
*= Doris Fang =*
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