Movies for TV - Early Television Foundation

LENSES 143
duces some spherical aberration at the sides, but this is kept to a
minimum by careful design.
In addition to the magnification and field variations in the
lenses, there is another property which changes with change of
lens and is most pronounced in telephoto lenses; this is perspective.
Everyone must have noticed with amusement sometimes
those race track shots made with a telephoto lens in which the
horses gallop away for dear life and never seem to grow any
closer to the camera. This is caused by the apparent perspective,
which will not be gone into here since it is somewhat beyond the
scope of this book, but anyone interested in technicalities can find
many good reference books at the local library.
Insofar as wide-angle lenses, and keeping objects in focus as
they approach the camera, are concerned, the effects are somewhat
different. With a wide-angle lens some highly interesting
effects can be obtained; although there is some distortion around
the edges, the rest of the picture is well in focus. For instance,
any object moving toward or away from the lens changes size
much more rapidly than it actually appears to, to the naked eye.
Some extremely interesting effects can be obtained by the judi-
cious use of the wide-angle lens. If it is desired to achieve a psychological
effect by a sudden pan shot of some horrible object with
the climax at the end of the pan, it can be done by arranging the
camera at the end of a row of gargoyles, or whatever is required,
and slowly panning up this row until the last one, at the end near-
est the camera, is framed. The last few images will grow rapidly
and by increasing the speed of pan, or decreasing the film speed,
a very sudden growth can be shown. This type of lens is invaluable
when there is little depth of set in which to work.
The standard one-inch lens, i.e., short focal length type of
lens, makes close objects larger and pushes the background fur-
ther away. A long focal length, such as a telephoto type of lens
on the other hand, will tend to show less linear difference between
distant objects and will push them closer together. If due care is
used in the choice of lenses for each scene, a considerable saving
in scenery costs can often be made.