ratio between key light and fill light is 100:50 or more simply 2:1. This same
procedure could be used to measure the lighting ratio for all lighting
instruments in the studio.
3. Contrast ratios, on the other hand, are measured quite differently. When
measuring contrast ratios, the important factor is the amount of light
reflecting off the screen, rather than the amount of light falling on it. The
surface brightness method of light measurement is used to measure contrast
ratios. To measure contrast ratio, it is necessary to measure the scene in the
different brightness areas (fig 2-3).
If the lightest area of the scene
reflects 200 footcandles and the darkest area of the scene reflects 20
footcandles, we have a contrast ratio of 200:20 or 10:1, well within the 30:1
contrast limits of today's color television cameras.
4. There are many different makes and models of light meters with varied
options and functions. When working with your light meter for the first time,
read the operating instructions and familiarize yourself with the light meter
prior to taking important light readings.
5. Once familiar with your light meter, a little practice using the different
methods of light measurement should enable you to measure the light levels on
your set precisely and accurately.
6. The beginning lighting technician often becomes a slave to lighting
measurements and ratios.
Usually, a quick check of baselight levels is all
that is needed for most lighting situations.
In especially critical
situations, it may be necessary to check reflectance of faces or bright
objects. Some lighting technicians get so involved in reading the light meter
that they forget to look into the monitor to see if the lighting looks the way
it was intended. If you, as the lighting technician, use your knowledge of how
the camera works and combine that knowledge with artistic sensitivity and
especially common sense, you will not have the light meter tell you how to
light; rather, you will use it as a guide to make your job more efficient.
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