St. Paul daily globe., 1894-04-23
COLOR PHOTOGRAPHY.
Il Further Advance by the Use of
Green and Yellow Screens.

Il Further Advance by the Use of
Green and Yellow Screens.
Baltimore Sun.
We recently described a method of
trIcolor photography, invented by an
American optician, Mr.. Gray, of New
York, by means of which the colors OF
nature may be reproduced in pictures
thrown upon screen. By using three
coiored pos ltlveS ana three lenses im-
ages are supermpOSed, one upon all
other. with admirable result. 1t is not
exactly photographing in cOlors, but the
desired effect is secured.
MIR. Arthur Burchett, of England, has
invented an analogous process of great
commercial! Importance for ''tranSlat-
lng' the colOrS Of nature into correct
monochrome values. An ordinary pho
tograph does not render colorS in due
proportion. Certain colorS have greater
effect upon the sensitive plate than
others. The actinism of blue rays and
of the sky, for instance, is so great
that 1t is extremely difficult to prevent
their action from being buried during
development.befo the effect of less ac-
tinic rays can be brought out. On this
account the prevalent usage is TO en-
pioy TWO negatives i'll order to produce
Scape. Objects of a yellow color, it is we'll
known, appear in photograph in tone
much lower than is proper to them, if
regard be had to their relative value III
the natural scale. The imperfection of
the whole system of tOne-renderlng in
photographs has long been considered
by painters as reproach to photog-
raphy. 1t has been impracticable, in
TACT, to photograph landscape, or paint
ng of anv kind. correctly. Certain colors
could net be given their proper value,
some taking too dark, others too light,
Commercially this was a serious mat.
tAr. as the illustration of books is
ffected at present chiefly through pho.
geography. The reproductions of the
works OF great painters would be vastly
more useful and acceptable if originals
could be translated correctly from color
to monochrome. The industry of max
Ing illustrations is large one, and the
demand for better method is very
great.
Mr.. Burchett's invention consists
simply of Interposing screens of green
and yellow glass between the combina-
tionS of the lens of the camera. A spe-
cial kind of green glass is necessary, and
the yellow glass must be placed behind
the green. The exposure has to be in
creased slightly, but nc special plate or
treatment i'll development is required.
An unexpected result is decided in
crease of the quality of the definition. A
lens with an aperture of "f22, for ex-
ample, will, with the help of the screens
OF colored glass, give the effect of using
an aperture of "f40." The practical
results are most happy The landscapes
produced by Mr.. Burchett reproduced
m n rIn fit,fc 1F -, IL
in their true relations of tone. The full
disk of the sun appears lis in nature. not,
as by ordinary methods, a black body.
Snow landscapes and the mists and the
greens and yellows of ferns, etc., are
properly given. The effect of ''atmos.
phere' is well secured. AS respects
paintings. it is enough to say that the
painters themselves are satisfied. The
public must, it appears. thank the in
ventor for valuable step of progress
in most interesting art.