LESSON 2
area of the negative. This use of the test strip will greatly reduce the
waste of valuable paper.
6. Distortion control. Many cameras have no means of perspective control.
As a result of these limitations, many negatives are made which show the
bottom of buildings as being very wide and the tops of the buildings as
being very narrow. This is not the normal view as we would see it. This
places the burden of correcting perspective on you and your lab knowledge.
a. Certain kinds of perspective can be corrected through the use of a
projection printer. This control is based on the fact that the farther the
easel is from the lens, the larger the image will be. If the image is
projected on a tilted plane, that portion of the image farthest from the
negative will have the largest image size. If the negative consisting of
parallel lines were to be projected onto a tilted plane, all portions of the
negative would converge, or not be recorded as parallel. By the same token,
a negative that has lines which are not parallel (within limits) could be
projected so that the print will show them as parallel. As an example,
suppose you must print a photograph of a tall building and, because of a
lack of controls on the camera, it was necessary for the photographer to
point the camera upward. This will cause the building to appear wider at
the bottom than at the top, or make the building look as though it were
leaning backwards.
b. This can be corrected in projection printing by tilting the easel so
the top part of the building is farther from the printer lens than the
bottom of the building, as shown in Figure 212, thus restoring the vertical
lines to their correct position. Figure 213 illustrates a building as it
would appear before correction, and the effects of tilting the easel during
printing.
c. When a projection printer is used with a tilted easel, use a very
small f/stop to maintain sufficient depth of field and keep the entire image
in focus. For best results, focus for the center portion of the picture,
and then stop down the diaphragm until the sides of the picture are brought
into focus.
You should now be familiar with the procedures used to obtain quality
projection prints. If there is any area that you are not sure of, go over
it again. If you feel competent in your knowledge of the material go to
Learning Event 3.
69
Previous Page
