Lens Characteristics and Specifi cations 247
3020
2m
Distortion (%)
Image height (mm)
100
1
0
1
Infinity
3020
Distortion (%)
Image height (mm)
100
2
1
0
1
Figure 14-10 Distortion for HC 150. The distortion for the HC 150 is shown at infi nity at the
right and for a distance of about 7 feet at the left.
@ 1:2
Distortion (%)
1
0
0102030
1
2
@ infinity
Distortion (%)
1
0
0102030
1
Figure 14-11 Distortion of macro lens. Distortion of HC Macro 4/120 mm at infi nity (right) and
at a 1:2 magnifi cation distance.
The ability or inability to record straight lines properly over the entire image area is the
only distortion caused by the lens design. Do not blame the lens for any other distortions that
might appear in your images, especially with wide angle lenses.
Foreshortening
When a subject or part of a subject close to the camera, such as the nose in a portrait or an
arm stretched out toward the lens, appears excessively large in relation to the rest of the
subject or scene we have foreshortening, not distortion. Foreshortening is caused when the
lens is too close to the subject or part of the subject. To avoid foreshortening, photograph at a
longer focal length from further away. Excessively large noses can be avoided if the camera is
at least 3 feet (1 m) away from the person.
Slanted Lines
Slanted vertical lines are frequently referred to as distortion, but again are not created by
the lens but by a tilted camera. Since slanted lines can be straightened by computer manip-
ulations, the need for considering this point when taking the picture is reduced. Trying to
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