Pages 81 thru 84 of my 6" by 4" OM4T instruction book covers the camera's
highlight and shadow control metering features. The highlight example
features three all white pieces of table crockery against an off white
background and the shadow control features an all black telephone against a
grey background.
As an experiment I took a spot reading with my camera from a distance of
about four feet of the non-polished black leather of an easy chair using 100
ISO film under fairly bright but cloudy lighting conditions. The reading was
1/30 @ f2.8. The same reading was confirmed by a 15 degree spot reading with
a Lunasix 3 hand held meter.
When I re-spot metered with the camera and then pressed the shadow control
button the exposure reading changed to 1/200 @ f2.8 which would result in a
photo of a darker shade of black!
I re-spot metered on the same chair and then pressed the highlight button
and the exposure changed to 1/8 @ f2.8. Now this surprised me because I
would have thought that for the highlight feature to work properly the
camera's meter would have had to have sensed something white or highly light
reflective. The longer exposure of 1/8 resulting from pressing the highlight
button even though the normal spot metering showed 1/30 tells me that the
highlight feature might be mimicking the characteristics of an incident
light meter. However, in actuality, the mimicking in this case is false
because the black leather is absorbing rather than reflecting light.
I guess that my question is this: is the combined spot metering and
highlight control feature an attempt to mimick the results of an incident
light meter reading and if so how close would two sets of readings [one with
an incident meter and the other using the OM4T spot & highlight feature]be
in conditions when a straight reflected meter reading would produce false
results ....... for example off snow or sand in bright sunny conditions
Also, if the spot and shadow control exposure has the effect of mimicking
an incident reading in reverse, so to speak, in cases where the subject
matter absorbs as opposed to reflecting an excessive amount of light [like
the black leather] I wonder whereabouts in the greyscale an off-black
subject would have to be when the spot and shadow control exposure would
match a straight spot reading.
I have taken photographs of dark objects and have relied upon spot metering
with my Lunasix 3 or my OM4T and the results have always been properly
exposed. Now that I have run the spot and shadow control experiment using an
admitedly dark subject [the black leather] and seen a jump in exposure from
1/30 to 1/200 at the same aperture I am wondering just how accurate the
combined spot and shadow exposure feature really is..
John Hudson
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