1-18. DESCRIPTION OF MINOR COMPONENTS.
a. Ground focusing glass.
The 4x5-inch focusing back and the 8x10-inch
focusing back are provided with a 4x5-inch ground focusing glass and an 8x10-
inch ground focusing glass, respectively. When either of the focusing backs is
installed on the camera, the ground focusing glass is positioned in the focal
plate to permit focusing the image from the lens and to define the picture
area.
b. Film holders.
Six 4x5-inch film holders and six 8x10-inch film
holders are furnished with the camera set.
During operation, a loaded film
holder is inserted in the focusing back. The film is positioned in the focal
plane to record the image after it has been sharply focused on the ground
focusing glass (a. above).
c. Filter holder.
The filter holder positions standard 4x4-inch
photographic filters in front of the camera lens. The filter is used when it
is necessary to alter the film spectral response. More on this subject will be
explained in greater detail in a later lesson.
d. Opal glass.
The opal glass provides even illumination when
transparencies, or other materials that are illuminated from the rear, are
being copied.
e. Camel's hair brush. The camel's hair brush is used for removing dust
from the glass parts of the camera set. The brush is contained within its own
metal case.
1-19. CAMERA OPERATION. Before you can confidently operate the 8x10-inch copy
camera, you must know something about the various controls and their functions.
a. Camera controls (fig 1-50).
CONTROL
FUNCTION
Front handwheel......................
Image size adjustment.
Rotating front handwheel
clockwise moves camera
toward easel to increase
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