Having only been recently (past 6 months) introduced to the marvels of
multi-segmented metering systems (e.g. matrix mode on the N90s), I'm at a
bit of a loss to explain why/how the system chooses an exposure in this
mode. (My comments below are based on contact sheet exposures, not
individual prints. The resulting prints either make the problems better or
worse, but that's another issue!)
My understanding goes something like this....
When using a spot system, it can be argued that the camera doesn't
choose the overall exposure, but tells the photographer how to expose
properly for any portion of the picture. The photographer needs to
understand his film latitude and limitations of his equipment in
setting the exposure.
With an averaging system (my most familiar system), the camera makes
an estimate of the correct exposure and the photographer can then "2nd
guess" the average reading based upon the brightness of the image.
Compensating, for example in a snow scene, is pretty straightforward.
With a multi-segmented system (like my N90s), the camera makes an
estimate of the correct exposure which seems to be based not only on
brightness, but also on the contrast of elements in the image. It can
be imagined that the intent is to combine the best of the average and
spot systems.
The results of using the matrix system have not been as successful as I'd
like. At times, the system seems to correctly compensate and at times will
be off by a stop or more. My attempts at documenting a recent boy scout
camp out in the snow show the default matrix settings to have some shots
perfect and others underexposed.
I'd appreciate any guidance as to how the matrix system "thinks".
Steve MacLeod
N90s in Kalamazoo.
