a. It is necessary to have some way of changing the lenstopaper
distance to provide for different degrees of enlargement or reduction. To
focus the image on the paper, a means to alter the lenstonegative distance
must be provided. A typical projection printer is shown in Figure 24.
Refer to it as you study this material.
b. The major components of a projection printer are as follows:
(1) A tungsten bulb is used as a light source. The lamp is enclosed
in a lighttight housing, which is ventilated to prevent excessive lamp heat
from damaging the negative.
(2) A negative carrier is two metal or plastic plates with an opening
in the center large enough to accommodate the negative. The negative is
placed between these plates and is held in position by its edges.