Movies for TV - Early Television Foundation

174 FUNDAMENTALS
other the tripack, method. The general features of each are simi-
lar, but each is again divided into two minor divisions: the inte-
gral bipack and the bipack magazine; and the integral tripack
and magazine tripack. The magazine tripack will be ignored for
it is used for 35 mm equipment only, is highly complex, expensive,
and completely unnecessary for television work. The integral tri-
pack, on the other hand,
is used all the time it is the well-known
Kodacolor and Kodachrome. Bipack film is used a great deal to-
day; the Cinecolor process uses it. Its only disadvantage is that
it is a two-color process and inevitably lacks some of the realism
of the three-color methods. The bipack processes are not used for
television work, and the integral tripack is the only one in general
use.
It may be of interest to examine the bipack operation. A spe-
cial type of magazine is used to accommodate the two separate
films which are used simultaneously. In most cases, a standard
camera can be used without more than a simple change in the lens
and view finder systems. Two films are fed through the lens gate
simultaneously. The film nearer the lens has an orthochromatic
emulsion which is sensitive to blue and green light, and the second
is panchromatic emulsion which is red- and yellow-sensitive. The
films are inserted with the two emulsions in contact: thus, there is
only a very slight difference in focus between the two images. The
orthochromatic film is coated with a light red varnish or lacquer.
This prevents green or blue light from reaching the panchromatic
film. It is important to use only cameras in good condition for
any play or slackness in the lens gate would at once result in an
out-of-focus frame. The tripack magazine is similar but uses three
films.
Prints are made from bipack film by dye-toning the two nega-
tives and printing them on a special positive film known as
stock. The emulsion is on both sides of the film and
duplitized
contains yellow dye to prevent an exposure on one side from
working through and affecting
the other emulsion. The emulsion
is, as might be expected, blue-sensitive. However, this type of