378 PHOTOGRAPHIC ENLARGEMENTS [Ch. X
Fig. 216. Gothic Type to Use on Drawings and the Appearance
when Reduced.
In the upper half are shown letters and figures of full size with their désigna*
tions by the printer, i. e., 24, 18, 12, 10, 8 and 6 point type.
In the lower half are showni the same reduced to one-half the length, and
reduced to one-fourth the length.
shown by the numerals and letters in fig. 216, if the drawing is
not to be reduced at all one can use 6, 8, or possibly 10 point type.
For one-half reduction (one-half off), the lettering should be
with 10 or 12 point type. For one-fourth size off), then the
lettering should be with 12 or preferably with 18 point type.
Projection Apparatus for Photographic Enlargements
§ 532. Enlarged prints of negatives.—There is great advantage
in making pictures of large objects at a considerable distance so that
the perspective will be correct and all levels in focus. It is also
advantageous to make pictures of microscopic objects without
undue enlargement, then there is greater sharpness of the object
as a whole.
If now one wishes a large picture, any good negative can be
printed by the aid of a photographic objective at almost any
desired enlargement. This can be done with projection apparatus
in a dark room by the following method : The management of the
projection apparatus is as for drawing. The negative is placed in
some kind of a holder and put in the cone of light from the main
condenser where the part to be enlarged will be fully illuminated
(fig. 132, 185). Care must be taken to so place the negative that
an erect image will appear on the printing paper (§ 512).
§ 533. Condenser required with negatives of different sizes.—
Remember that the diameter of the condenser must be somewhat
greater than the diagonal of the part of the negative to be enlarged
(§314 and fig. 114). For example, to use the whole of a lantern-
slide negative (85 x 100 mm., 3X x 4 in.) the condenser should
have a diameter of 14 cm. (5^ in.).
For a negative 100 x 125 mm. (4x5 in.), the condenser should
be 18cm. (7in.)indiameter; fora negative 125 x 175 mm. (5x7m.),
the condenser should be 23 cm. (9 in.) in diameter and for a nega¬
tive 200 x 250 mm. (8 x 10 in.), the condenser should be 35 centi-