The Ketchum keystone. [volume] (Ketchum, Idaho) 1885-1899, 1894-03-10
GREAT PHOTOGRAPHY.
A Picture OF Mont Blanc Taken
nom . Distance OF Eight Miles.
The Marvellous Outcome OF -Four Months'
experimenting Of . Noted Sw7ss
Sciantist-A Delicate and Dif-
dcult Process.

A truly marvellous development IN
camera work is what has been termed
telephotography, whereby. pictures of
distant objects can be made with the
same clearness and sharpness of detail
as if they were close at hand. But to
secure q successful picture by this
process many difficulties have usu-
ally to be contended with, and accord
ing to the St. Louis Globe e-Democrat it
is comparatively seldom that the most
favorable conditions occur. The main
difficulty is the presence in the air Of
minute particles of dust. In large
towns, and even in their neighbor-
hood. the air is filled with an incon-
ceivable quantity of such particles,
and the result is grayness of the at
mosphere, which, on the Photographic
negative, blurs the outline of remote
objects. Where these conditions OBJ
tain it is possible to procure a good
proof only in the morning after noe
turnal shower has cleared the air.
Such is the absorbent power of dusty
air that all attempts at taking long
distance photographs in the vicinity
of Paris, where much experiment
ing was done, resulted unsatisfac-
torily beyond range of thirty-two
hundred yards, even when the occasion
was apparently propitious. In the
neighborhood of the sea and of the
mountains, where the air is much
purer, photographs can be made at
much greater distances; but here
single obstacle presents itself in the
unequal density of the various strata
O. air. Especially in hot weather, GER
tain beds of air, heated by the rays of
the sun, will be actuated by an up
ward movement and this imparts q
trembling appearance to the land
scape. The presence of rivers or
marshes, or land much exposed to the
solar rays, is likely to give rise to ver-
tical currents of vapor OF great absorp-
tive power. Again the humid vapors
of the atmosphere clothe far distance
with blush haze, which confuses the
lines of the picture and obscures the
effects of light and shade. This is rem
edied by employing orthochromatic
lenses and yellow glass to neutralize
the blue tint. The camera must be
absolutely still, the most minute vibra-
ton being multiplied indefinitely and
causing hopeless confusion in the neg
ative.
It will thus be seen that telephotog-
raphy is both a difficult and deli
cate process A most remarkable illus
tration of its possibilities has been
achieved by NJ. Boissonnas, of Geneva,
in a photograph of Mont Blanc, taken
at a distance of eight and one-half
miles. The proof has been published
by Nj. Fourier, who also shows, in
order to suggest more strongly the
nature of the achievement,
the size the picture would be If
taken by an ordinary object glass.
The latter measures nine and one
sixteenth inches by three-eighths
inches, and the telephotograph is five
and three-fourths inches by three and
inches. The lines of the
massive, far-off mountain stand out in
bold relief, and the details of the in
country are distinctly
shown. Such a picture, however. is
not made without almost unlimited
pains and perseverance,. It cost M.
Boissonnas four months of expert
before he could determine on
the best place and the best time at
which to take it. For the benefit OF
those who may have to tread wearily
over the same ground, he tells the
condition that obtained at the event |
full moment. It was six o'clock in the
evening. about twenty minutes before
the sun sank behind the mountains.
From experience he found that this
was the most favorable moment to OBJ |
tain a harmonious proof, and the dis
tinctness of outline and details in the !
clouds was greatly increased from the
fact that they were tinged first with q
pale yellow and then with orange.