The Camden chronicle. (Camden, Tenn.) 1890-current, 1891-08-14
PHOToGRAPHlNG STARS.
interesting Information Concerning
the Art.


California, gave an interesting lecture
ut the rooms Of the Camera. Club in New
York the other evening upon astronom-
zeal photography. He said, observes
a Pittsburgh Dispatch writer, that as
Economical photography presented few
difficulties, and that more knowledge
of astronomy was required than of
photography by the observer; in other
words, that the ratio between the two
was about three parts of astronomy TO
one part of photography,
if, however, a photographer should
attempt to photograph "a star he would
find that his image would be blurred,
owing to the movement of the object
during the exposure; therefore it was
necessary that the instrument must be
kept in motion in keeping with the mo-
ton OF the star, and the apparatus for
photographing stars, therefore, adjusted
10 meet these difficulties. The usual
method of keeping the star on the plate
in photographing was by moving the
telescope, but owing to the size of the
instrument at the Lick Observatory this
was impossible, as the telescope weighed
seven tons. The plan adopted, there
fore, was to make the plate movable by
means of turning screws.
When the photographer wished to do
some OF his work the thing first to be
done was to move the big telescope SO
that lens could be capped over the
end. 1t is necessary to put on
a different lens for Photographic
purposes, and it happens that
a different focus is obtained in
the big telescope. The dry plate
is therefore placed in the tube nine
feet from the eye piece, hole having
been cut in it for that purpose A seed
twenty six-plate is used and for develop
ment an ordinary pyro and potash. The
developer is used very weak and plenty
of time given to bring out the image.
When the plate is developed the opera
tor has to go at it in a blind sort Of fash
ion, as the smaller star images will
not appear till the developing work is
done.
The photographs of the planets are
more difficult to secure, owing to the
refraction in the atmosphere. Some
fairly good pictures have, however, been
made of Jupiter and Saturn, and pic
lures of Mars will be taken. Prof.
Keller showed pictures of the planets
and the moon, as well as drawings to
Illustrate the difference between the
two. The outer ring of Saturn, which
was not discovered till the big Lick tel
escope was turned on the planet, does
not show in the photograph. The pic
lures Of the Milky Way which Prof.
Keller has in his collection of lantern
slides are most excellent, and are the
best ever taken. The hundreds of stars
shown on the picture are none of them
visible to the naked eye.
The photographs of the planet Jupiter
showed plainly the different positions OF
the spots and bands on the surface Oh
the planet, which demonstrate that they
are constantly changing, and that prob
ably the surface of Jupiter is mass OF
changing matter.
1t is well-known fact that better
photos are obtained through the smaller
telescopes than through the big ones
Photographing the stars, especially the
small ones, is tedious work, as in some
cases the exposure must last for severa
hours. During all shat time the plate
or telescope must be moved so that tho
image of the star will continue in ono
place. The exposure for Il star Of thC
sixteenth magnitude is two hours, anC
only one at time can be secured un
less the stars happen to be of the same
magnitude, SO that getting clusters il
particularly long and tedious in It's ope
ration.
In procuring the Photographic sta
pictures, often what is known as tn,
trailing process is followcd-that is, tn,
plate is exposed to the star, ana then II,
attempt is made to fix the image in on
place, but it passes along oyer tla plate
making trail. A number of trails can
of course, be got on one plate, and thel
studied out and measured aftcrward.
The exposures for planets are short
that of sun spot taken in Paris wa
abont as nghtnlng-llke as possible, tn
shutter being attached to the stronges
kind of spring. The exposure Tor tn
moon takes about quarter Of a SECOND
and that for Jupiter about four seconds
People who visit the Lick Observator
often ask very remarkable questions i
regard to the telescope as well as to tn
methods of photographing the stars
The covering of the observatory is mad
of three-inch steel plates, and of eours,
is arranged so that a plate can b
moved to allow the telescope to point t
any part of the heavens. A visitor VIII
happened into the observatory when a
the plates were closed asked most ca
nestly if the steel plates were transpa
ent. A frequent question asked in r.
gard to star photographing is il flasl
light is not used to make the eXposur
There is an old saying that intelligel