Camera Work: A Photographic Quarterly (1907 (Heft 20))

NOTES
COLOR

RELATING TO
PHOTOGRAPHY.

AMONG the many problems connected with that of taking
photographs in natural colors is one, the solution of which,
though of extreme importance, has received but scant attention
from investigators :
I refer to that peculiarity, that, while certain photographs must represent
the objects in the colors in which they are seen at the time of taking, a great
many others must be made to represent the objects as they would appear if
illuminated by white light.
Reproductions of landscapes and exteriors belong to the first category,
while reproductions of paintings, art objects, etc., belong to the second.
Portraits, also, generally belong to the second, but for reasons to be later
developed, they, as well as mural paintings and frescoes, may, in some cases,
be classed in the first category.
A moment’s reflection will show the reason for this classification. It is
evident, even to the most unobservant person, that the color of a landscape
varies enormously at different hours and on different days. These differences
in color are not only those due to the progressive absorption of the different
light rays by the increasing thickness of the atmospheric stratum as the sun
sinks lower and lower, but are also due to local atmospheric conditions. It is
clear that a color photograph of such a landscape must be a faithful interpre-
tation of the conditions existing at the time of the taking of the photograph.
In the case of color photographs of paintings, art objects, etc., this
interpretation of existing conditions is not desirable.
It is obvious, though the eyes of the great majority of people are not
sufliciently trained to observe it, that the colors of such paintings, etc., vary
with the atmospheric conditions. The colors of a painting in a studio
exposed to the north and illuminated by a blue sky are not the same as those
of the same painting exposed to direct sunlight.
This being admitted, it is clear that the duty of the photographer is, to
either illuminate such objects with white light, or, to so change the relative
exposure for the different colors as to obtain this result.
An idea of how much these relative exposures must be varied in order
to reproduce white as white can be obtained by referring to the results of the
experiments of Messrs. Precht and Stenger, who, on one day, a sunny one,
found the relative exposures necessary to obtain white to be
Blue Green Red
1 3.2 8.8
and on another day, a dull, cloudy one, found that to obtain the same
results, the exposures had to be
Blue Green Red
1 5.1 21.3
Portraits, and by that I mean ordinary portraiture, not genre composi-
tions, obviously come under this class. It would be manifestly unfair to


35