a. Sheets of plastic are excellent for protecting an original from physical damage and for
keeping the original flat during handling. However, do not use plastic coverings on originals when
copying because they:
(1) are seldom optically pure
(2) are hard to hold flat
(3) distort the copy
(4) reflect light, causing hot spots
(5) reflect images of other objects in the room
b. If possible, a piece of optically pure flat glass should be used to flatten your original when
copying. Window glass is not optically flat.
Figure 3-2. Horizontal copying
c. Be sure to mount the original so it can be uniformly illuminated.
2.
How to place the lights.
a. Natural light (sunlight) is excellent for copying. House lamps, however, are poor for copy
work because the light is seldom uniform. If you are working outdoors, find an open shade area to work
in. The shade side of a building is best. When using tungsten light, place the original so that it gets light
from both sides, or use reflectors so the original is illuminated as uniformly as possible.
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