While modern cameras routinely have fully automated
exposure control, older cameras offer a variey of metering solutions
ranging from no metering at all through to automated metering.
This piece attempts to explain some of the terms
used when describing older metering systems but please note, it is
only concerned with cameras with built-in meters.
Types of meters
Most older cameras have either a selenium cell meter
or a CdS meter. The CdS metering system requires a battery - check
that a suitable battery is still available. A few cameras have an
extinction meter which requires no batteries but is difficult to use
and possibly less accurate. For more about extinction meters, see
extinction meter instructions, which give a good explanation of
how one is used.
The majority of older cameras with meters have a
match-needle meter. This will have either a display window on the
top plate or a viewfinder display, and sometimes both. The display
will show a notch or needle and a moving pointer. Match the pointer
to the fixed marker to get the correct exposure or a correct exposure
An uncoupled exposure meter means that the meter
reading has to be transferred from the meter display to the camera
aperture ring and shutter manually. On some cameras the meter reads
in exposure values (also called light values), which are set on the
A coupled meter has a linkage between the meter and
the camera apertures and/or shutter speeds so that when the meter
is set, the settings are automatically transferred. For an example
of how to use a camera with a coupled meter, see Voigtlander
Vito CLR instructions.
Exposure Values were an idea which appeared on many
cameras of the mid-fifties and after.
A camera with an exposure value shutter has a linkage
between the aperture ring and the shutter speed ring and a new scale,
the exposure value scale. The linkage can be disengaged, usually by
pulling one ring gently away from the other, to set a new exposure
reading. This is done using the EV scale.
After that, as long as the light stays constant,
all that is required is for the desired shutter speed or aperture
to be selected; an increase in shutter speed will automatically bring
about a reduction in aperture so that the amount of light falling
on the film remains constant. Similarly, increasing the aperture causes
a reduction in shutter speed.