This is Cinerama...at the London Casino
The 70mm Newsletter
by: W. G. Altria,
Ideal Kinema, October 7, 1954
is Cinerama...at the London Casino. By W. G. Altria, Ideal Kinema,
October 7, 1954
Architects FRANK BAESSLER in association with T.,P. H., & E. BRADDOCK,
F/ARIBA, M I Struct. E
CINERAMA, which made its British debut in London last week, is a
three-film system of wide-screen presentation.
It is not stereoscopy; but the Cinerama camera exposes three films
simultaneously, and the images are projected in synchronism on to a
deeply curved screen, to give a picture covering a field of vision 146
deg, wide and 55 deg. high, and as this closely approximates to the
field of human vision it creates an illusion of depth and reality which
is enhanced by deep focus photography.
The Cinerama camera has three 27-mm. lenses, set at angles of 48 deg.
apart. Each lens takes one-third of the picture, recording it upon one
of the three standard 35-mm. films. The axes of the lenses converge and
cross at a point 11/16 in. in front; the left lens takes the right
portion of the picture; the middle lens points straight ahead and takes
the centre portion; and the right lens takes the left portion.
The three films must, of course, be projected by three separate but
electrically interlocked projectors, to produce the composite picture,
and the projectors must be carefully orientated to correspond with the
angles of the taking lenses. This necessitates the use of three widely
spaced projection booths, one to the left of the auditorium to project
the right-hand portion of the picture, one in the middle to project the
centre portion and one on the right to project the left-hand portion.
in 70mm reading:
in70mm.com's Cinerama page
image to see enlargement
Absolute mathematical accuracy
must be maintained in positioning the projection rooms in relation to
the screen to obtain accurate registration of the three pictures. To
avoid" keystone effects the projector apertures must be lined up as near
as is possible to the vertical centre of the screen. It is also
essential that the audience should be seated with the eye level as near
as possible directly opposite the screen; in other words, a steep angle
of vision must be avoided.
The London Casino Theatre was selected, after an exhaustive survey, as
the best available in London for the showing of Cinerama. Nevertheless,
considerable difficulties had to be overcome to make it entirely
suitable for the purpose.
of the three Cinerama projection rooms installed at the London Casino.
The British architects in
charge of the installation had to send to their American colleague an
accurate survey of the auditorium and other relevant sections of the
theatre. From this information a set of drawings was prepared in America
exactly setting out the position of the projectors, the size and
curvature of the screen (which in this case is 64 ft. wide by 23 ft.
high) and the ventilation and safety requirements according to American
practice. The British architects then had to bring these into line with
the requirements of the theatres section of the London County Council;
this entailed considerable elaboration of the ventilation system and
In America, air can be drawn from the auditorium into the projection
booths; in London, fresh air has to be trunked in from the outside of
the building, and a mechanical extract system had to be provided with an
outlet to the exterior of the building. The LCC insists upon separate
exits from the projection rooms, each with a ventilated lobby, and
isolated from the auditorium and public. These regulations necessitated
more elaborate arrangements than are needed in America.
whole show is monitored from this control room in the auditorium.
The problems arising from
these requirements have been successfully overcome without a radical change
in the appearance of the auditorium.
It has been possible to retain nearly all the seating in the stalls level,
where the projection booths had been installed; the circle seating remains
unchanged, but part of the upper circle is not being used because of the
steep angle of the sight-lines.
Stereophony is regarded as an essential. A seven-track system is used.
On the production side, five microphones are placed to pick up separate
records of sound emanating from sources within the field of the camera. Up
to three microphones may be used to the sides or rear of the camera position
to record sounds from sources approaching, or leaving, the field of the
soundhead and pre-amplifiers.
The seven tracks are
re-recorded on to a separate magnetically coated film and are reproduced in
the theatre by a soundhead, located in the normal projection room, and
synchronised by an electrical interlock system with the Cinerama projectors.
Five of the sound tracks operate five speaker assemblies behind the screen.
The other two feed the auditorium effects speakers.
The preamplifiers are in juxtaposition to the soundhead. Contrary to normal
practice, the power amplifiers are located as near as possible to the
speaker units-five backstage and the remainder in the projection booths.
The sound system has been made specially to the Cinerama organisation's
specifications. Technical data are not available for publication, but it is
stated that the system is capable of handling a frequency range from 30
cycles up to 18,000 cycles, well into the upper harmonics. This compares
with the 60-8,000 cycles frequency range of standard sound reproduction
systems, and is indicative of the importance which the Cinerama designers
attach to high-fidelity reproduction.
amplifiers for screen speakers.
Although the film used for
Cinerama is of standard 35-mm. gauge the frame is higher than standard,
extending over six sprocket holes instead of four. The three films,
therefore, form a composite picture with an aspect ratio of nearly 3 to 1.
The rate of projection of the images is 26 frames per second instead of the
standard 24 per second.
The projectors, made by the Century
Projector Corp. of New York, a subsidiary of the Westrex Corp., basically
are of standard design modified to the requirements of Cinerama.
The mechanisms are geared, of course, for the appropriate intermittent
motion, and the main drive motors are controlled by differential motors
which provide a fine degree of adjustment so that the speeds of the
projectors can be advanced or retarded to maintain the pictures in
synchronism. An unusual feature is that the drive sprockets and guide
rollers have spring-loaded flanges on one side to reduce the possibility
of film weave in the gate.
of one of the arcs.
To overcome the problem of sharply defined joins between the three pictures
the projector gates are fitted with vibrating saw-toothed masks at the sides
of the aperture plates.
There are three dowsers between the film and the arc lamp instead of the
customary two. The extra dowser is the sync. dowser remotely operated from
the main control console.
In addition, the machines are equipped with water-cooled gates further to
protect the film from over-heating and to reduce expansion of the gate when
the oscillating mask plates are working.
The Exelite arcs have motor-driven
carbon-feed mechanisms, automatically controlled to maintain constant
intensity of light. However, variations in the brilliance of the three
pictures are liable to arise because of differences in the density of the
three prints: even by modern processing standards it is difficult to obtain
prints matched to the accuracy demanded by the Cinerama system. To
compensate for this, metal gratings are interposed between the lamps and the
gates. They are pivoted at the vertical centres, and when the gratings are
moved away from the vertical, the angle of the slats to the axes of the
light beams is changed, and this cuts down the amount of light passing
through to the apertures. The gratings are actuated by servo motors for
architects impression of the auditorium of London Casino. Parts of the three
projection rooms can be seen on the extreme left.
Click image to see enlargement.
To minimise the width of the
projection booths and encroachment upon seating accommodation in the
auditorium, each booth is equipped with only one projector. If standard
2,000-ft. reels were used, seven stops would be required during each
performance of the Cinerama programme, which runs for 110 minutes. To
obviate this, the machines are fitted with magazines for 8,000-ft. reels and
this enables the programme to be run through with only one short interval.
The magazines have conventional fire traps and take-ups, but the spindles
have been increased in size to sustain the additional load, and separate
drive motors are used for take-up drive.
In addition to the projector, each booth is equipped with a rewind machine
capable of handling the 8,000 ft. reels. As the Cinerama films are on
cellulose acetate base (safety stock) rewinding is permitted in the
projection room; but not while the show is in progress. A separate room has
been equipped for maintenance work on the films, including synchronising,
cutting and splicing.
size of the 8000 ft spools can be seen in this picture of the maintenance
room, where any necessary synchronisation, cutting and splicing can be
carried out by the staff.
The Casino's original projection
room has been re-equipped with Westrex British made standard projection and
sound equipment. This is used for the showing of the prologue and for
fill-in items in the event of a breakdown of the Cinerama programme.
Centralised control of the complex array of equipment is absolutely
essential. Provision is made for this in the master control console located
immediately in front of the central projection booth.
From this position the control engineer operates and monitors the entire
deep curvature of the 64ft by 23 ft screen is illustrated in the picture
above, taken from the upper circle, and in the picture below, which shows
the supporting framework and three of the speaker assemblies.
A series of green lights on the
control panel indicates when the three projectors and soundhead are laced-up
and in stationary synchronism. Switches are provided for operating the house
lights and the screen curtain, and for starting and stopping the projectors
and soundhead. A further series of red flashing lights gives a visual
indication that the projectors are running in synchronism or otherwise.
Below are individual controls for advancing or retarding the speed of the
projectors so that they can be brought into step with one another, and the
controls for regulating the brilliance of the three pictures. There is a
master volume control, and facilities for varying the connections of the
auditorium speakers to the effects tracks. Generally, one effects track
operates the speakers on one side of the theatre and the other those on the
opposite side. In certain sequences, however, the sound effects are required
to move from the front to the rear of the auditorium or vice versa, and the
control engineer manipulates the switching accordingly. An inter
communication system is also provided for the transmission of verbal
instructions between the control console and the booths and other points in
the Cinerama projection and sound apparatus was imported from America with
the exception of the speaker units. These are British-made by Westrex.
The vast curved screen is of unusual construction. The centre portion passes
through an arc of 120 degrees, symmetrical about an axis, with tangent
extensions, through an arc of 13 degrees, at each end of the centre portion.
The total arc of the screen equals 146 degrees-the angle of photography of
the Cinerama camera.
The centre portion of the screen is made of a single piece of perforated
material, similar to that used for standard screens, but the extensions at
the sides are made of 7/8 inch strips of perforated material. The angular
displacement and spacing of the strips are adjusted to avoid cross
reflection of light between the side portions of the screen.
steel framework supporting the screen and ancillary equipment is the work of
two companies. Sterling Foundry Specialities, Ltd., supplied the series of
standard Sterling-Safway workstage towers, and the Unistrut metal framing
system marketed in this country by Sankey Sheldon, Ltd., is used to tie the
rowers together, and to support the loudspeaker assemblies, the screen and
the cantilevered frame-work for the screen masking, curtains and control
The Sterling Safway unit frame scaffolding is interchangeable with the
American Safway, which has been a standard form of scaffolding in America
for a number of years. Because of its strength and stability it has been
used for all the Cinerama installations in America.
image to see enlargement
Its advantages lie in itís principles of built-in safety, the ease and speed
with which it can be erected, and its exceptional load-bearing properties.
The Unistrut metal framing system, introduced in 1939 by Mr. C. W. Attwood,
an electrical contractor of Wayne, Michigan, but practically unobtainable
until war-time material shortages ended, consists of a steel channel
section, It in. square, cold rolled from 12 gauge material, available in 10
ft. or 20 ft. standard lengths. The channel is treated with a rustproofing
material, and finished stove enamelled olive green. Hot dip galvanised
finish is also available.
In America the Unistrut system has been used in conjunction with the Safway
towers for Cinerama and exclusively for a large number of CinemaScope screen
Building work and redecorations were carried out by C. E. Wilkinson, Ltd.
For the three projection booths in the stalls reinforced concrete suspended
floors are built on brick foundation walls. Above floor level the booths are
constructed of foam slag block partitions plastered externally. The internal
faces of the new partitions are clad in heavy duty Fibreglass quilt over
which is fixed perforated asbestos sheets on a specially made metal trim.
image to see enlargement
The old ceilings have been removed and new suspended ceilings formed and
covered with Fibreglass quilt and acoustic plaster board. The ventilated
lobbies are constructed of clinker block partitions plastered on both sides.
The company also was responsible for joinery and builders' work in
connection with the ventilation plant.
The Thames Bank Iron Company supplied and installed the ventilation system,
with mechanical inlet and extract, for the three booths.
There is an 18in. by 21in. centrifugal fan, with two ranges of galvanised
ductwork connecting the booths with the outside of the building. The arc
flues are connected to the extract ducts by flexible and lagged trunking.
The electrical installation and wiring was carried out by the Strand
Electric and Engineering Co., which also fitted the neon signs on the front
of the building.
image to see enlargement
From the intake at the rear of the theatre the supply is connected to two
transformers of 400V input and 117V 10KVA single phase and 210V 30KVA
output, respectively. Cables are run from the secondary side of the
transformers to a main intake panel in one of the projection rooms and from
here feeds supply the other projection booths. The supply for the arcs is
obtained from selenium rectifiers, one in each booth.
Ancillary work included wiring for new primary and secondary maintained
lighting systems, ventilation fans, curtain motors, and auditorium speakers.
In addition to the stage speaker systems there are two effects units on
each side wall at front stalls and front circle level. There is also one
unit in each of two theatre boxes at the rear of the stalls, with two
similar units, connected in series, on the circle level.
Ship plain HI rotating 10-mm. positive carbons and 8-mm. negative carbons
are being supplied for the arcs.
The uniforms for the male and female staffs were made by Uniform and General
Services Co., Ltd. The colour scheme is navy blue. The male staff is
supplied with smart tunic-style uniforms trimmed with gold, and the
usherettes are dressed in tailored Eton-type jackets trimmed with gold,
modern full-flared adjustable skirts, and white blousettes with black bow.
The seating and carpets at the Casino supplied by W. W. Turner and Co.
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