> Wait a second! How will the camera know if 123, 123, 123 is really a white
> fence in the shade or a grey card in full sunlight? I think you are
> making a mistake here, as RGB seems to be more useful when you are dealing
> with a light source of known intensity (such as a monitor, a
> slide-scanner, or a printer), but if it doesn't have a baseline reference
> for maximum brightness, it will fall on its face.
The F5, (and all cameras with matrix metering) do have a baseline for
absolute, rather than relative brightness.
All AF lenses transmit the lens's maximum aperture to the camera so the
meter "knows" what the absolute brightness of the subject is. I'm certain
that is taken into account when metering.
You are right, the camera still does not know the difference between a white
fence in the shade or a grey card in sunlight (same absolute brightness).
But it does hava some idea of what is before it, and seems to perform very
well usually.
