Movies for TV - Early Television Foundation

LIGHTING 163
In setting up stage lights, there are certain rules which have
already been given. In order to implement these rules,
it is neces-
sary to measure in some manner the light which falls on the subject.
There are a number of ways in which this can be done; the oldest
and most useless is by guesswork on the part of the producer. When
emulsions and equipment were cruder, more could be blamed on
them and the laboratory which did the processing. But today, in
spite of the increased latitude of film, much more care is required
both for television and for film work. A preciseness has come into
the field which leaves no room for "guesstimation." Production
costs are so high today that a man who uses that method will soon
find himself without a payroll provider.
Fortunately the requirements are not so exacting
that it is neces-
sary to use laboratory equipment to do a good job. Therefore,
simple photoelectric meters can be used to determine the light
present. This meter works on the same piinciple
as the television
camera tube: that is, it is photosensitive. When light falls on one
of the electrodes in the meter, usually a flat strip
of metal coated
with one of a number of different salts which are affected by light,
it generates a voltage. This voltage is proportional to the intensity
of the light falling on it. Hence, the stronger the light, the greater
the deflection of the needle. The meter may be calibrated in a num-
ber of ways: some show the stop to use for a given film emulsion,
others the American Standard number to be used in further calcula-
tions. Still others give a direct reading of the light intensity in candle
power.
Whatever method is used, the application of the information
is not difficult. For live work, of course,
there is no emulsion to
worry about, only the lens aperture and ratios of one light to
another. The meter itself is quite small about the size of the old-
fashioned "turnip" watch, and perhaps a little thicker. It is usu-
ally suspended around the neck by means of a black cord; it has
the effect of making the wearer look important, if nothing else.
There are two ways to use the standard meter, the direct and
the reflected method. The former is newer and appears to be
coming into favor with more people every day. Its use necessitates