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 designa- 

 tions by the printer, i. e., 24, 18, 12, 10, 8 and 6 point type. 



In the lower half are shown 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., 3^ 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 1 8 cm. (7 in.) in diameter; fora negative 125 x 175 mm. (5x7 in.), 

 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- 



