c. Most cameras permit the viewfinder to be used as a playback monitor
for the VR. The advantage of having all these controls is that you do not
need any additional equipment to set up the camera.
11. Camera lens. One type of lens can give you a wide vista, although you
may be relatively close to the scene, another type may give you a close view
of an object that is quite far away from the camera.
Different types of
lenses also determine the basic perspective, whether you see the object
distorted or whether you perceive more or less distance between the objects
than there really is. Because the lens determines what the camera can see,
you need to know the basic optical characteristics of the lens and the chief
operating controls.
a. All broadcast-type cameras are equipped with a zoom lens, or as they
are sometimes called, variable focal length lenses.
Some of the older
monochrome cameras used individual, fixed focal length lenses, which were
mounted on a lens turret so the camera operator could quickly flip to one of
four lenses. Each of the four lenses performs its specific function. The
focal length of a lens determines how wide or narrow a vista a particular
camera has, and how much and in what ways objects appear magnified. Lenses
are identified by their focal length, such as:
(1) wide angle, or short focal length;
(2) normal, or medium focal length;
(3) narrow angle, or long focal length.
b. The wide angle or narrow angle refers to the field of view, the
relative vista of the lens. The short and long refers to the actual focal
length, the distance from the optical center of the lens (often the midpoint
between the front and back lens elements) to the point where the distant
image as seen by the lens is in focus.
(1) With a wide angle, or short, lens, you can see more, you have a
wider vista. Objects very close to the lens appear quite magnified, but the
ones just a little further back look rather small. A short lens creates an
effect similar to looking through binoculars the wrong way.
(2) With a narrow angle, or long, lens, you have a narrow vista. But
what you see, even the distant object, is greatly magnified. A long lens is
similar to binoculars used correctly.
(3) The normal lens gives you approximately the view of normal human
vision.
c. Contrary to the fixed focal lenses, the zoom lens can assume all
focal lengths from the wide angle position to the narrow angle position.
This is why it is called a variable focus length lens. You will learn more
about the zoom lens in Lesson 2, Learning Events 1 and 2.
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