General Notes On Exposure Metering - Leica MP Bedienungsanleitung

General notes on exposure metering

Most subjects normally have even distribution
of dark and light subject details. This kind of
normal subjects reflect 18 % of the incident light,
corresponding to a grey scale value to which all
exposure meters are calibrated.
If the subject actually reflects more light, e.g. a
snowy winter landscape, a bright sandy beach,
white house walls or a white wedding dress, a
shutter speed and aperture setting in accor-
dance with the exposure meter display would
result in underexposure.
By contrast, subjects with predominantly dark
details, e.g. a black steam engine, dark grey slate
roofs or a dark blue captain's uniform, reflect
less light and a shutter speed and aperture
setting in accordance with the exposure meter
display would result in overexposure.
In this kind of cases, the exposure meter value
has to be corrected, if you are aiming for opti-
mum exposure results. This is not the case if you
use selective metering and take the measure-
ment from part of the subject with a good distri-
bution of light and dark details.
For example, in a wedding photo you can take
the measurement from the bride's face and not
the white wedding dress. For landscape photo-
graphs using a wide angle lens, the camera can
be tilted until the LEICA MP's selective metering
field does not record the bright sections of the
sky.
If there is no suitable section of the subject to
measure in this way, it is necessary to use a
compensation factor, i.e. the shutter speed is
extended by 2 to 4 times or the aperture is
opened by 1 to 2 stops.
For sunlit snowy ground, for example, the com-
pensation factor is 4, i.e. instead of the metered
shutter speed of 1/1000 s at f/8, the exposure
uses either 1/250 s at f/8 or 1/1000 s at f/4.
For less bright subjects, e.g. a bright beach, an
compensation factor of 1.5 is sufficient. The
reverse procedure is used for dark subjects.
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