Some photographers
prefer to use a spot meter which only reads the intensity
of light from a very narrow angle. This allows the reading
to be taken from a very specific tonal area of the subject.
In fact, the photographer can take a series of readings
and know exactly where the tonal details of both the highlights
and the shadows will fall on the film. The ASA film speed
is dialed in and the reading transposed to a scale that
gives the appropriate camera shutter speed and aperture.
The subject is observed through a telescopic eyepiece
and a superimposed circle shows the small area being measured.
The meter is switched on by pulling a trigger and the
correct f-number is lit up as a digital display.
