Leica M6 TTL, Instructions Manual, Page: 29 / 54

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Meter sensitivity
The light metering range begins at 0.03 cd/m
2
.
The working range at ISO 100/21° extends
from -2 to 20 EV (exposure value), i.e. from 4 s
(shutter speed dial position "B") at f/1 to
1/1000s at f/32 (see also diagram on page 29).
Very low light levels
Should the light level fall below the range of
the exposure meter, the left triangular LED
flashes.
Since the meter uses the working aperture, the
LEDs may also flash when the lens is stopped
down.
The exposure meter remains on for approxi-
mately 12 seconds after finger pressure is
removed from the shutter release button, even
if the light level is below the threshold
sensitivity level. If the light level improves
during this time (e.g. if the composition is
changed or the aperture opened), the LEDs
stop flashing and come on permanently.
General information on exposure
metering
Most scenes contain an even distribution of
bright and dark subject details and reflect an
average of 18% of the light falling on them.
This value of 18% corresponds to an average
grey tone to which exposure meters are
calibrated. Very bright subjects, such as snow-
laden winter scenes, sandy beaches, white-
washed walls or a white wedding gown, reflect
more light toward the exposure meter, tending
to result in underexposure.
Predominantly dark subjects such as a black
steam locomotive, dark grey slate roofs, and
navy-blue uniforms reflect much less light, and
meters tend to overexpose. To achieve correct
exposures in these cases, the measured
values must be corrected, unless exposure is
measured selectively by inclusion of only a
portion containing a representative sampling of
dark and light subject details. You would for
example meter on the bride's face and not on
her white gown. A landscape shot with a wide-
angle lens should be metered with the LEICA
M6 TTL pointing downward to exclude the
bright sky.
When no such metering alternative is availa-
ble, a compensation factor of 2x or 4x can be
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