Controls for Creating Effective Images on Film or Digitally 309
arranged in a curved line, everybody from center to the edges can be at the same distance
(see Figure 16-13).
This is not, however, the way lenses are designed nor how they record a subject. Every
lens is designed to record a sharp image on the fl at image plane from a fl at subject in front of
the lens, whether the subject is a building, a fl at document, or a group of people. If this were
not the case, the walls of a building and a document would also have to be curved to ensure
sharpness from left to right and top to bottom. For good overall sharpness, arrange the group
in a straight line. If you prefer a curved arrangement for artistic reasons or for better fl ash illu-
mination, feel free to do so, but be aware that you need more depth-of-fi eld. For this you need
to close down the lens aperture because the people on the outside are now closer to the
camera than those in the center.
Figure 16-13 Photographing groups. When people are arranged in a straight line, the people at the
edges are farther away (here, 14 feet) than the people in the center (9 feet) when measured
from the center of the lens. Arranged in a curve, they all can be at the same 9-foot distance.
Lenses, however, are designed to produce a sharp image from a fl at, not a curved, subject plane.
If the group of people is arranged in a curved line for other reasons, the lens aperture must be
closed down because you need more depth-of-fi eld — from 6 feet to 9 feet in this example.
BACKGROUND SHARPNESS
The lens aperture not only determines the actual depth-of-fi eld range but also the degree of
blur in subjects in front of and beyond the depth of-fi eld range (how sharp or how blurred
backgrounds appear in the photograph). Because backgrounds are a dominant part of many
pictures, the degree of sharpness or unsharpness in the background often determines the
effectiveness of the fi nal picture. Check the degree of sharpness or blur in the background and
possible foreground subjects before you take the picture. To do so view the image with the
aperture closed down to the value that you plan to use for the picture. Blur in backgrounds
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