101
Switching off the exposure meter
If the camera will not be used for a long period, or
is stored in a bag, it should always be turned off at
the main switch. This stops any power consump-
tion, including the slight consumption that contin-
ues in Standby mode after the exposure meter has
turned off automatically and the displays have
gone out. This also prevents accidental expo-
sures.
Metering diagram (see also p.103)
The metering diagram applies to both exposure
modes, aperture priority mode and manual set-
ting.
Details of the measuring range of the exposure
meter can be found on the right-hand side of the
diagram, while details of the working range of the
focal plane shutter can be seen on the left. The ex-
posure values (EV) are shown in the middle.
The metering range of the exposure meter is indi-
cated on the right-hand side of the diagram, in
cd/m
2
(candela per square meter).
The ISO film speed values (Sv) are shown at the
top of the diagram.
The different exposure speeds in seconds (Tv=
Time value) are shown on the left-hand side of the
diagram.
The working range of the LEICA M7 focal plane
shutter is represented schematically by the shad-
ed area in the adjacent column. With the "B” set-
ting, the upper section is unrestricted.
The aperture values (Av) are shown on the lower
left-hand side.
Example A shows the correlation between the film
speed, luminance (brightness), exposure and
aperture.
First follow the vertical line from the film speed
(ISO 100/21°) down to the intersection on the
horizontal line representing the corresponding
luminance.
In example A, this is 4000 cd/m
2
, i.e. a typical
value for bright sunlight. The line now runs diago-
nally to the vertical line indicating the aperture
(11), and from there horizontally to the required
speed (1/250s). In the course of this diagonal
line, the exposure value (15) can also be found.
Example B shows that in candlelight and with a
film speed of ISO 400/27° (cd/m
2
), photographs
should be taken with an aperture of f/1.4 and a
shutter speed of 1/15s. An aperture of f/11, for
example, can no longer be used as the corres-
ponding shutter speed of 4s is not available
To Next Page
