THE LENS
The anamorphic lenses supplied with the CinemaScope
Package have been designed as frontal attachments to the regular
projection lenses, and represent an approximate 6 1/2" of extension
beyond such projection lenses in installations using projection
lenses of a diameter of 225/32", and an approximate 9 1/2" in
installations using projection lenses of a diameter of 4".
At the present time, projection lenses of focal lengths of
5.00" or less are furnished in barrel diameters of 225/32", and
projection lenses in focal lengths of 5.25" and over are furnished
in barrel diameters of 4.00", though in older types these longer
focal length lenses appear in the smaller diameter barrels. It is
recommended, however, that this latter type be replaced by new,
higher quality, highspeed lenses.
Should the surveyed projection heads be fitted with a
shutter in front of the projection lens, some modification of that
arrangement may be necessary.
Some present projection lenses may not be of sufficiently
high quality to permit the undistorted projection of the
CinemaScope picture and replacement of such projection lenses
is desirable, and may be essential.
Should the survey indicate a change in picture height
outside of the range set forth in THE APERTURE,
then additional projection lenses are required in any event, and these in all cases
should be of high quality and should have a flat field.
The aperture and the anamorphic lens have been designed
to produce a picture of an aspect ratio of 2.55 to 1; that is, the
width is 2.55 times the height.
THE APERTURE
The aperture dimension for the CinemaScope picture is
.715" x .912", resulting in an increase in height of the present
picture by about onesixth if the present projection lenses are
retained. In practice, this dimension is entirely actual only in the
case of headon projection.

In angular projection, that is at greater angles of projection
throw than zero degrees, the aperture plate, being, delivered with
a lesser opening than its nominal dimension, may be filed to the
opening required by the individual situation as a correction for
keystoning.
This, as at present, is an onthejob operation.
Accompanying these instructions are two charts being (a)
a chart of the CinemaScope picture sizes resulting from the use of
various focal length lenses at various throws at intervals of 10',
and (b) a similar chart of picture sizes for the present
conventional aperture of .600" x .825", obtained from the use of
various focal length lenses at various throws, also in the intervals
of 10'.
An examination of the chart indicates that for the same
picture height, different size projection lenses will be required for
the CinemaScope picture and for the present conventional
picture.
Since heights increase somewhat with the angle of the
throw, some account must be taken of this
difference.
The actual picture widths given in the CinemaScope
tables are figured upon the chord of the screen and not upon the
arc.
For definitions of the terms chord, arc, rise and radius as
they apply to the CinemaScope picture, see the chart and
diagrams covering these terms and fixing these dimensions.
THE PORTS
(Not included in CinemaScope Package)
Since the beam from the anamorphic lens diverges
immediately it leaves the lens, and the width of the beam is,
generally speaking, more than double the width of the present
beam, the present beam should be measured at the port and at
any enframement of the port to determine the width required for
the CinemaScope beam, and where necessary, ports must be
enlarged and enframement of the ports cut away.
