Method of making large pictures from small negatives.
[Illustration: TN: The Enlarging Camera.] [p204]
The prevalent use of the Detective Camera, and other cameras, for
making pictures on small plates, has caused a demand for an
apparatus whereby large pictures may be produced from such
negatives.
This demand has been met by the production of Anthony's New
Enlarging Camera in connection with the Gelatino bromide papers.
This enlarging box is at once simple and effective. It consists of a
black wooden box containing a good kerosene lamp. The sides of the
box have a number of grooves that carry a slide holding a large
condensing lens, O, while another slide holds the negative, N, that
is to be printed.
[Illustration: TN: Schematic of the Enlarging Box.]
To the outside of one end of the box is attached a sliding bellows,
and an objective, E, by which the picture is enlarged and thrown
upon any white surface. In a few words, the enlarging box is a small
solar camera, but using artificial light instead of the sun's rays;
or it is a magic lantern so arranged that no light can come out of
it except that which passes through the objective. [p205]
The use of the instrument is as simple as its construction. The lamp
is lighted, and then adjusted in the box so that a shadowless circle
of light is projected upon a white wall or other surface, all the
light being utilized by means of the reflectors situated back of the
lamp. This adjustment is effected by moving the condensing lens and
the lamp nearer or farther apart. It is perhaps best to place the
condenser in a groove near the objective, but sufficiently far from
the end of the box to allow the slide containing the negative to be
inserted. Having obtained a good circle of light, now place the
negative in the slide and adjust the slide in the box so that it is
between the condensing lens and the objective, and as close to
former as may be. By means of the objective a good focus is now
obtained, and we are ready for an enlargement.
With this apparatus and an artificial light, of course rapid
printing paper is necessary. The cap is placed on the objective, and
by the aid of red light a piece of the gelatino bromide paper is
adjusted on the surface where the image was projected from the
enlarging box. This part of the operation maybe assisted by removing
the cap from the objective and placing a piece of ruby glass before
it, allowing the image to fall on the paper through the ruby glass.
A simple and effective way of holding the paper is to tack two
common wooden laths upon a board in such a way that they will serve
to hold the paper along two of its longer sides, in which case the
board must be used to focus upon.
The exposure necessary will depend upon the density and character of
the negative. With a medium density in a portrait negative, one
minute appears sufficient, but something also depends upon the
paper [p206] used, those of English manufacture being rather
slow. With a little care and this little contrivance much pleasure
and success are attainable in enlarging pictures from small
negatives.
The use of the new "tooth" surface printing paper admits of the
application of crayons to the enlargements.
By substituting the lime or the magnesium light for the kerosene
lamps, pictures may be printed by the collodio chloride process upon
a variety of uneven surfaces, such as plaques, plate, saucers, pots,
etc., etc.
In fact, this instrument might very easily be converted into a solar
camera by fixing it in a window and adjusting a mirror outside that
would reflect the sun's rays into the condenser within the box.