g. If the image is not of the proper size after focusing, repeat the
procedures in e. and f. above until a sharp image of the desired size is
obtained.
h. Move all four locking handles forward to secure the carriages.
i. Gently lift the press focus lever.
The shutter will close.
1-25. ADJUSTING LIGHT ASSEMBLIES AND DETERMINING EXPOSURE. To adjust the light
assemblies, follow the-procedures in a. below.
To determine the exposure
required for the type of copy and image size used, follow the procedures in b.
below.
a. Adjusting light assemblies.
Adjust the light assemblies as follows:
(1)
Position your head in front of the lens assembly and study the
illumination of the material to be copied.
(2)
Readjust the light assemblies to produce an even illumination
with no glare
b. Determining exposure. The exposure required for the type of copy and
the image size used may be estimated by the operator, based upon experience.
Normally, however, an exposure meter must be used. When an exposure meter is
used, proceed as follows:
(1)
Operate the exposure meter to measure the light from the
material to be copied, and to determine the exposure setting (f/stop and
time) for the light measured and for the film used.
(2)
The exposure setting obtained (b (1) above) is correct for
objects at infinity (a lens operating at a distance from the film equal to
the lens focal length).
However, the lens used with the camera set
operates at a distance from the film much greater (due to the bellows
extension) than its 12-inch focal length.
As a result, a corrected
exposure setting (CES) must be determined (calculated).
(3)
Calculate the corrected exposure setting (CES) as follows:
(a)
Measure the bellows extension (distance from the center
of the lens to the film plane).
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