Archived posting to the Leica Users Group, 1998/04/07

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Subject: Re: [Leica] Incidence Light Measurements
From: "Martin V. Howard" <marho@ida.liu.se>
Date: Tue, 07 Apr 1998 17:04:28 +0200

Joseph Codispoti wrote:
>
> Incident meters are not panacea for all types of photos.  In portraiture
> one has to consider that adjustments must be made for skin lighter or
> darker than 18% gray if the face is predominant in the photo.

At the risk of starting a heated debate on the subject, isn't the statement
above a bit of a nonsense statement?

Take a bunch of people and let them hold a grey card (18% reflection).
Some people are going to have skin which appears lighter and some are going
to have skin that appears darker than the grey card.  Why shouldn't the
exposure be the same for all of these!?  If we meter of the persons' faces
directly (using a reflective meter), or "adjust" for skin tone using an
incident meter, we're not exposing correctly.

With the argument put forth above, we should expose the film differently
depending upon whether the 18% grey card is shown in the shot or whether
only the person's face takes up the frame.

It makes sense to expose according to the amount of light falling upon a
subject/scene, rather than the reflective properties of the subject/scene.
That way, dark subjects are reproduced as such, and light subjects are
reproduced as such.  Provided that the film can hold the tonal range in 
the scene, from shadow details to highlights, the exposure will be correct.


M.

- -- 
Martin V. Howard, Application Systems Laboratory,     | Now fully
Dept. of Comp. & Info. Sci., Linkoping University,    | Y2K compliant.
SE-581 83 Linkoping, Sweden.  Tel +46 13 282 421,     +----------------+
Fax +46 13 142 231; marho@ida.liu.se; www.ida.liu.se/~marho; ICQ 354739