Figure 4-23.Front and rear vertical tilt movement.
The front standard swing allows the lens to pivot
horizontally around its optical axis. The swing front is
used to increase the depth of field. When the swing back
is swung, the film is not parallel with the image
produced by the lens. By swinging the lens, you can
bring the image onto the same plane as the film.
2. Vertical tilt. Both the front and rear standards
tilt vertically (fig. 4-23).
The tilt back is used to correct distortion, or
perspective, in the vertical plane. When you angle the
camera up to photograph a subject, such as a building,
the vertical lines on the ground glass appear to converge.
When this distortion is not corrected, the subject appears
smaller at the top and the vertical planes bend toward
the center of the image (fig. 4-24, view A). To correct
this distortion, tilt the tilt back so it is parallel to the
vertical plane of the subject (fig. 4-24, view B).
The tilt front is used to focus and increase the depth
of field. When the tilt back is tilted to correct for vertical
distortion, the film plane is no longer parallel to the
image produced by the lens. By tilting the front standard,
you can bring the image of the lens onto the same plane
as the film.
PHAN M. Lakner
Figure 4-24.Uncorrected and corrected vertical distortion.