When the copy work done in your lab is considerable and includes many large originals, the type of copy setup used by the graphic arts shops may be needed.

The type of camera used in graphic arts photography is called a process camera. Although larger than other types of cameras, it is similar in principle. Since the process camera is built for copying, it has a copyboard and other features not associated with the average camera. There are two types of process cameras: horizontal and vertical.

Most horizontal process cameras are known as darkroom cameras because the camera back is built into the darkroom wall. Because the back of the camera extends into the darkroom and the front is housed in a separate room, you can load the film, focus the camera, make the exposure, and develop the film without leaving the darkroom. Of course, it is necessary for you or a helper to go outside to place copy in the copyboard before the exposure is made.

In recent years, vertical process cameras have become more popular because they take up much less

floor space. This makes them especially useful aboard ship.

CAMERA ADJUSTMENTS. Each copy camera has slightly different adjustments. You should consult the operating manual of your copy system to learn the proper operation and controls of your particular system. Only the minimum basic components of a copy system are discussed in this chapter.

GROUND GLASS FOCUSING. Ground glass focusing is essential for exacting copy work The image of a document viewed on the ground glass of a copy camera provides a means of monitoring all aspects of the image as it will appear in the reproduction. This includes image placement, image size, and any apparent unwanted reflections.

BELLOWS EXTENSION. A copy camera should be capable of a bellows extension of at least two, and preferably three times or more the focal length of the lens being used. With a 3-inch lens and a bellows extension of two focal lengths (6 inches) and the original is positioned four focal lengths (12 inches) from the film plane, a 1:1 ratio of the original size to reproduction size is obtained. A reproduction with a 1:1 ratio can be referred to as life size. A bellows extension that is less than two focal lengths cannot produce an image as large or larger than the original. A bellows that can be extended more than two focal lengths can produce an image larger than the original.