128 THREE-DIMENSIONAL PHOTOGRAPHYadjustable in width, and a pair of filters, one red and one blue.
A plunger in the bottom serves to change the filters in the aper-
ture.
The attachment has a rectangular window which fits the G.E.
exposure meter when the hood is removed. To use it, the attach-
ment is placed upon the meter and the incident light allowed to
fall upon the filter. The diaphragm is closed until the meter reads
either ‘‘10’’ or ‘‘20.” Then the plunger is released to change filters
and the meter reading taken. A scale attached to the filter case
then indicates the color temperature which corresponds to the
second meter reading.
As meter cells may vary a little in color sensitivity, the filters
of the attachment are graduated in density and may be balanced
to correspond to the meter sensitivity by moving one or both
sidewise. The meter is quite satisfactory, and appeals to many
because it is inexpensive and because it permits the use of only
one meter unit for both exposure and CT reading.
Another type of meter is one designed and built for just one
purpose, that of reading color temperature. The Guild labora-
tory uses the Rebikoff, a Swiss meter of more than two percent
accuracy. This meter, instead of the usual scale, has an arc made
up of a blue sector, a red sector and a heart-shaped black zero
point set in a transparent housing so the needle position may be
seen from either side.
A dial is set upon one side of the meter in a position similar
to that occupied by the dial of most exposure meters. However
this dial is transparent, and beneath it are located the two cells
with their filters. The dial itself carries a semicircular black mask
so that, as the dial is turned, the areas of red and blue exposed
to the light, constantly vary. Because this dial must be exposed
to the incident light it is convenient at times to hold the meter
in the palm and look down upon it and at other times to hold it
up before the face, directed away from you. The transparent case
makes the needle position easily visible in either position.
The dial carries an index point which directly indicates the
color temperature of the light. It also carries a symbol of the sun
and of an incandescent bulb. When either of the two latter sym-
bols lie opposite a fixed index mark on the case, no filter is neces-