COLOR IN STEREO 127Thus seven, nine or 11 pairs will meet most needs, while the.
addition of B8, Bi and B%, respectively, adapts the three films to
ordinary home lighting. I would suggest the extra pair for late
daylight and an extra one for blue sky light, plus the mazda home
light, making a total of ten pairs of filters, or less than half the
full set. Such a series of ten pairs should meet 98 percent of the
requirements as long as you stick to one film type.
Incidentally never expose any film out of doors without a filter
because of the ultra-violet exposure which will result. When day-
light film calls for “0” filter, use a haze filter.
Color Temperature (CT) Meter.-There have been a number
of CT meters offered from time to time. One of the earliest was
the Eastman which we are told is no longer available. Of the
more recent models, the first was the visual meter of H&H. This
is a disc-shaped black plastic case with a graded series of visual
filters around the edges. The filters range in color from definite
blue to an equally pronounced purple. A shield over the side of
the meter obscures all but three of these filters, although by ro-
tating the body of the meter, the full sequence passes behind this
triple mask.
A white reflecting sheet of controlled color is used as a stand-
ard. It seems strange to speak of the color of white, but there
are a great many colors ranging from pale cream to very pale
blue which pass ordinarily as “white.” This reflecting sheet is
of a white color which reflects red and blue equally.
The reflector is held so it is illuminated by the light which
falls upon the object. The disc is then rotated while looking
through the filters at the reflector. There will be one set of three
adjacent filers; one appears blue, one seems to be a blue-gray and
the third shows a distinct tinge of purple. This is the end point,
and the reading of the scale at that point indicates the color tem-
perature of the light.
This meter is good, as far as the instrument is concerned, but
most people do not have the sensitivity to color which makes it
possible to arrive at a positive end point, and even those who do
have sensitive color perception, are often unsure and so may be
off one full point of the scale.
To overcome this difficulty H&H brought out their color at-
tachment. This is a square case which contains a slit diaphragm,