Chapter 3 The Video Camera and Support Equipment
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Imagine that you are standing in the front of the classroom,
facing the other students. From this vantage point, some of the
students in the third row of desks, are not completely visible.
Parts of their bodies, such as arms or hands, are blocked by students in
the first and second rows. From your perspective, Rachel’s left arm and
hand are hidden. If you take a few steps down the aisle to stand even
with the second row, you can see Rachel’s arm on her desktop without
a problem. As the camera (your eyes) moves into the set, the viewing
perspective changes. Your body’s movement is a dolly move. Another result
of the dolly move is that Rachel gets larger in the picture because you are
closer to her. This movement will “feel” realistic to the viewer.
Move back to the front of the class to examine this situation with a
camera zoom. Rachel’s left arm is blocked from view again because Bill, in
the second row, is obstructing your view. Do not take a single step toward
Rachel. Instead, pick up a pair of binoculars and view Rachel through
them. She is larger in the picture, just like in the dolly shot, but you are
still unable to see her arm. This is because Bill is larger now as well, and
is still blocking your view. This movement is like a zoom shot with a video
camera because it does not change the visual perspective. You will not see
Rachel’s left arm until either you move, Bill moves, or Rachel moves. This
shot “feels” flat and unrealistic to the viewer.
Visualize This
When an image passes through a zoom lens, it is turned upside down, or
is inverted. The physical location within the lens assembly where the inversion
occurs is called the focal point, also commonly known as the optical center.
The focal point, or optical center, may not be in the center of the lens assembly
as measured in inches, Figure 3-13. For example, the center is 3″ on a lens that
measures 6″ long from front to back. The focal point is the point where the
image is inverted, regardless of the physical location inside the lens assembly
or the distance from the front or back of the lens assembly.
As mentioned above, when the outside ring of a zoom lens assembly
is rotated, one or more of the individual lenses inside the lens assembly
moves backward or forward. You can see this movement by looking into
a zoom lens as it is manipulated. As this piece of glass moves forward
focal point: The physical
location within the lens
assembly where an image
is inverted. Also commonly
called the optical center.
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Focal point
6 inches
3 inches
(geographic center)
Figure 3-13. The optical
center of a lens is not
always in the physical
center of the lens
assembly.