275
Chapter 12 Outdoor Photography
Copyright Goodheart-Willcox Co., Inc.
A further difficulty is the slight difference
between the point of visible-light focus and
the point of infrared focus. Some older lenses
indicate the infrared focus position with a red
dot, Figure 12-27. The image is focused normally,
and the barrel is then rotated slightly to align the
focused distance with the red dot.
Because infrared film is sensitive to such a wide
spectrum, it must be handled in complete darkness
from the time its packaging is opened until it has
been developed and fixed. To avoid possible light
fogging, keep a camera loaded with infrared film
out of direct sunlight as much as practical.
Most digital cameras cannot be used for
infrared photography because the manufacturer has
installed an infrared-blocking filter in front of the
image sensor. Cameras can be modified by having
the blocking filter removed, but the conversion is
costly and must be done by a trained technician.
Jack Klasey/Goodheart-Willcox Publisher
Figure 12-26. The photo at left was taken with panchromatic film; the one at right, with infrared film. Compare the way
each film “sees” the different elements of the scene.
Jack Klasey/Goodheart-Willcox Publisher
Figure 12-27. A red dot marked on the barrel of
older manual-focus lenses is used to correct focus for
infrared film.
IR focus