i. Projection lens sets (figure 210). Three projection lens sets,
having focal lengths of 2, 3 1/2, and 5 3/8 inches, are supplied with the
printer. Each lens board has been cut off at two diametrically opposed
sides of the top to permit bayonettype mounting, and each is equipped with
a bracket on which the red filter assembly can be mounted by a knurled
FIGURE 210. Projection lens sets.