Movies for TV - Early Television Foundation

124
FUNDAMENTALS
a further loss occurs. It would seem to be a miracle that a picture
of any kind is obtained! Actually, the losses are so small that they
do not amount to much once the film has been recorded, and in
fact sometimes the actual process of reproducing the film introduces
effects which tend to cancel these losses.
Before describing an actual installation, it would be well to
consider the problems involved in taking a picture of the television
screen. At first sight it might appear that what would be required
is a camera focussed on the kinescope. Most receivers do have a
bright enough picture to enable photographs to be made. But since
the complete picture is on the screen for only one-thirtieth of a
second (remember thirty frames per second) it means that the
maximum lens-opening time is only one-thirtieth of a second. This
at once introduces a fixed constant into the calculations ; the shutter
speed has been determined. Now for the amount of light available.
In home receivers, this would easily become a problem and the
various designers have solved it in two ways. One system, Para-
mount's, involves the use of a standard ten-inch tube producing a
picture about three by four inches. The other uses a small, five-inch
projection tube with a very brilliant blue picture. Each method has
advantages and each provides sufficient light. This gives us two
we know the shutter opening and the amount
figures to work with ;
of light available. From this it is possible to determine the size of
the lens opening / or T value by taking into account the speed
of the emulsion. So we're all set to go or are we? What happens
if we shoot at thirty frames a second?
The television frame and the camera will be in synchronization
because they are running at the same speed, and the program will
be properly recorded. (Yes?) Now, what happens when the film
is processed and sent to station XXXX-TV in the wilds of Wis-
consin? It is placed on the projector and exhibited. But wait a
minute, there is something wrong! What is it? Why, the people
are all very tired, they move so slowly. Perhaps the is
projector
running too slowly? No, that's the proper speed. Ah ! The film was
made at thirty frames a second and projected at twenty-jour, so of
course it is running more slowly than when it was made and the