The Houston daily post. [volume] (Houston, Tex.) 1886-1903, 1900-05-04

placed as 10 De perfectly STEADY Inc peSt
way to secure the most desirable results
aud at the same time have the tripod so
that it will not interfere with the move
ments of the operator in focusing Is to set
up the tripod SO that one leg of it points di-
rectly toward the object to be photo
graphed. By this means the remaining
two legs will be in such a position that
one may stand between them in arranging
the camera,
After the camera is IN position and the
screw OF the tripod which holds the camera
has been tightly set. the cap is taken from
the lens the shutter opened by using the
time exposure and we are ready to
focus our picture on the ground glass
screen at the back of the camera.
The Opaque focusing cloth is then
thrown over the back OF the camera and
brought closely down over the head in
such a manner as to shut out all possible
daylight from the back of the camera.
The only light we want is that which
comes through the lens at the front.
Focusing is generally done by means of
screw at the front OF the camera, which
racks out or in, as the case may be, thus
increasing or decreasing the distance Of
the lens from the screen. This focuses
the ray OF light passing from the object
through the lens 10 the screen, making
the picture clear and distinct upon the
glass. AS the picture becomes sharply TO-
cused upon the screen We notice hrst that
ut is reversed. or upside down. (The rea-
son for this Is given in the chapter oil
lenses.) We soon get accustomed to see
ing cur pictures and focusing them in this
upside down position.
While focusing We have opened the lens
wide, and having now focused the image
on the ground glass as sharply as possible
paying particular attention to point
about one-third the length of the plate.
we must make use of the daphragms, or
stops
II our camera has a shutter the dia-
phragms are fixed in the shutter aud
either represent revolving disk with diff
icrent sized openings or open and close
by means OF little wings piyoted together,
called iris diaphragms
II the camera has no shutter, what are
termed waterhouse diaphragms are used.
Theso are SETS of metal plates with OPEN
lngs OF different diamete:G. ANY partic-
uiar plate or diaphragm may be placed in
me IL. diaphragm slot which Is cut in
the lens for the purpose
one reason for selecting a house or
building for first trial of focusing the
image correctly on the plate is to demon
etrate the use Of the sliding front and
the swing back. If the camera is set up
perfectly level we will probably find that
we nave quite an expanse of foreground,
put only one half or three-quarters of the
mouse Tor height on the ground glass.
rms Is caused by the house being so much
higher than the camera. If one cauld
ascend platform that would place the
camera on level with the center of the
mouse this trouble would be avoided but
TINS OF course, is impossible. The diff
Guilty is overcome by having the front Of
the camera so that it can be raised or
lowered. There is a thumbscrew on the
side OF the front Of the camera. This
needs only to be loosened, when the Who'll.
front can be raised to the height re-
CURED. The screw should then be tight
ened. thus holding the front in place I,
sometimes happens that even by raising
the Siding front to its greatest height
me entire building can not be focused
upon the ground glass, a portion OF tho
upper part OF the building still being cut
on, In this case We have to resort to lift-
ing the camera upward e.. pointing the
iens signify toward the top Of the build
lhg-as one Of the fundamental rules az