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of energy radiated by tungsten in the region between
600 and 700 mp.
The reflecting power values of colors, as measured
on a specified photographic material and with a
definite quality of illumination, should be of great
value in motion picture work. These values show
definitely at what point on the tonal scale the color
in question will be rendered. In the past a great
deal of confusion has been caused by the fact that
the photographic process did not render colored objects
at the same point on the tonal scale as that at
which they are seen by the eye, and it was necessary
for the photographic technician to learn by experience
just how a given color would be rendered.
The advent of Panchromatic film and light sources
relatively rich in long-wave radiation obviates this
difficulty to a great extent since a fairly close approximation
to orthochromatic rendering is obtained.
Carefully determined photographic reflecting power
values, however, for the colored objects to be used
in a set should be very useful. It is well known
that it is difficult for the eye to estimate the correct
tone value of color under all conditions, especially
in the presence of contrasting juxtaposed colors. Although
the photographic technique used may give
orthochromatic rendering, it is quite possible that
the observer in judging the scene may be somewhat
misled as to the point on the tone scale where certain
colors will be rendered. If photographic reflection
factors have been measured and are available,
it is possible to adjust the tonal composition of
the set definitely and thus assure the desired result.
It should be remembered, however, that photographic
reflection {actor depends not only upon the
colored object but also upon the quality of the illumination
and the spectral sensitivity of the photographic
material. While it is probably impracticable
to measure the photographic reflection factor
of every object used in a set, it does seem entirely
feasible to standardize, to a certain extent, the use
of color in set decoration. In any large studio, it
should be possible to establish a certain number of
standard colors (such, {or instance, as wall paints)
and to predetermine their photographic reflection
factors. These reflection factors at once establish
the positions of the colors on the gray scale in terms
of which they must be reproduced. The end members
of the gray scale are, o{ course, black and white
with intermediate gray between. Practically, the
blackest black available reflects from 2 to 4 per cent,
while the whitest white reflects {rom 85 to 90 per
cent. In establishing the gray scale, however, it
should embrace the entire theoretical limits extending
from 0 to 100 per cent. This gives a scale from
0 to 100 and the position of any object can be 1ocated
on the scale directly by its reflection {actor.
It should be remembered that the visual sensation
produced is proportional to the logarithm of the
stimulus and not to the stimulus itself. This means
that il we wish to establish a gray scale having uniform
sensation steps, the increment from step to
step must be in geometrical progression rather than
arithmetical. For instance, a brightness scale of 1,
t 38l
2, 4, B, 16, etc., units gives a series of equal sensation
steps, while the gray tone scale mentioned above
as defined in terms of reflection factor, extending
from 0 to 100 is entirely satisfactory and of practical
utility. This logarithmic characteristic of our
visual response should not be forgotten in applying
the results to studio problems.
DISCUSSION ON
MR. JONES' PAPER
Mn. Vorcr: We are greatly indebted to Mr.
Loyd A. Jones for the paper he has given, and we
'wanr to express a debt o{ gratitude to the Eastman
Kodak Company, the General Electric Co., and all
the other great corporations that have so generously
sent their famous engineers and scientists out here to
the coast. Mr. Jones is Past President of the Society
of Motion Picture Engineers, which Society
has contributed so largely to the scientific results
that have been obtained in the industry. About a
year ago I had the pleasure of entertaining Mr.
Jones and saw a great deal of him out at the studio.
When he talked to rne on various subjects like he
has talked to you he would end by saying: "It's all
very simple," and I said: "No, I don't see how
simple it is-now will you please say it all over
again so I can understand," and then he would back
.rp and tell it to me in what he called A, B, C,
and I was then able to get about 10 per cent of it
and then he told me in still simpler A, B, C, and
then I would get a little more. So, ladies and gentlemen,
do not be frightened by Mr. Jones' mysterious
words and curves, for he can tell it so even
I can understand, and will, I know, be pleased to
answer any questions.
Mn. Nrcror-eus: I am afraid Mr. Jones and
myself cannot get into an argument because I agree
with him. I don't know in what way I can elaborate
on his talk as he {ully ccvers the subject.
I enter this discussion as a sort of a sympathetic
representative of our cameramen'
This discussion tonight should be very fruitful
and I hope it will result in studio color technique
going to one color or monotone.
The discussion of color for sets has gone on at
studios for years and one can see the reason for not
mixing colors when as Mr. Jones has just said,
there are about one hundred and fifty thousand
different shades of color. Imagine a set painted in
difierent shades of different colors, such as many
sets are painted. Who could tell just how the different
tones will photograph ? This is of ten responsible
for bad photography and wh5r do this when any
one color can be split into eight shades with white
on one end and black on the other. This I have
called monotone and is now the vogue at most
studios.
I was very giad to hear Mr. Max Factor. He
was very kind to come here and talk about make-up
and that we will have monotone make-up. There
is no reason why there should be eight colors on