98
Example A highlights the relationships between
the film speed, light intensity (brightness), shutter
speed and aperture.
From the film speed value (ISO 100/21°), first
trace the vertical line to its intersection with the
horizontal line for the given light intensity. In this
example, this is 4000cd/m
2
, which corresponds
to the brightness in bright sunshine. The line then
runs diagonally as far as the vertical line for the
set aperture (11) and from there horizontally to the
left until it reaches the necessary shutter speed
(1/250s). The exposure value (EV15) can also be
read off in the diagonal course of the line.
Example B shows that in candlelight and with a
film speed of ISO 400/27° (1cd/m
2
) it is neces-
sary to use aperture 1.4 and a shutter speed of
1/15s. Aperture values beyond f/5.6 cannot be
used as they call for longer shutter speeds than
the longest, i.e. 1s, available on the shutter speed
dial. Due to this, direct metering is no longer pos-
sible. Conversion or reading the correct shutter
speed from this diagram is therefore essential.
Metering field size in the viewfinder
(Graphics see p.100-101)
The diameter of the circular metering field is
12mm. This corresponds to
1
/
2
of the format
height,
1
/
3
of the format width, and approx. 23% of
the format area. However, in the viewfinder image,
the metering field size varies slightly depending
on the lens being used and the distance set.
This also applies for lenses with a viewfinder
attachment, such as the former LEICA ELMARIT-M
135mm f/2.8.
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