IN less than nine months the old Wembley Film Studios have been transformed into the Wembley Television Studio Centre, headquarters for the ITA programme-making activities of Associated-Rediffusion, Ltd.

Only last January work was still in progress at the old Wembley on the film “The Ship That Died of Shame,” but by September 22, the new Wembley was ready for the start of commercial television.

In that comparatively short period the original building has been virtually demolished, one large stage has been converted into four (which are, incidentally, about half as high again as the original), with their complementary multiplicity of control rooms and electronic equipment, involving the installation of close on 20 miles of sound, vision and control cables.

What can best be described as the “technical area” is partly a two and partly a three-storey structure within the main building. On the first floor are the operational control rooms for the stages, and on the second floor is the master control room and the remote control of the lighting equipment. The telecine room is a separate building, but immediately adjacent.

Floor Accommodation

Apart from the studios themselves, the ground floor is occupied by viewing rooms, camera and lighting control rooms, technical stores and work- shops. First floor accommodation includes further control rooms and announcer’s quarters.

The four stages so far completed (a fifth is planned for a later date) are rather smaller in superficial area than is normal in a film studio, and one, No. 3, is really no more than an insert stage.

All, however, are equipped with spot-rails and the flooring is of a special hard grade of rubber, which, it is hoped, will obviate the dangers of buckling and consequent bumping during movement by cranes and dolleys.

As it is common for a television studio to be made more acoustically “live” than the equivalent film studio, a large area of the original acoustic treatment of the walls has been covered by perforated hardboard.

An innovation that might well commend itself to film studios is the addition of visitors’ galleries. These glass-fronted compartments provide an adequate view of what is happening on the stages, but are so well sound-proofed that it will be possible to fit them with low-level amplifiers so that onlookers may hear as well as see what is going on.

Such an arrangement could be a boon to harassed film directors, especially those allergic to sightseers while they are working!

Marconi Mark III cameras, with 44 in. pick-up tubes are being used for studio operations, and similar cameras, but with 3 in. tubes are employed on outside broadcast work, for which there are two magnificently equipped self-contained vans that will, when necessary, have a micro-wave link with the studio. Altogether 21 cameras will be in operation or on call when programmes are going out.

The vision-mixers are of the Marconi relay-operated type, which handle eight inputs. All the sound-control equipment has been supplied by Marconi’s, with optical groove-locator turntables that allow the pick-up to be dropped on the precise required point on the record by an optical plotting system.

The telecine apparatus, made by EMI, is of the 16- or 35-mm. “flying spot” type, and a control system, claimed as unique in this country, has been devised so that the machines (once they have been loaded) can be operated from a remote position.

In addition, there are some RCA Vidicon apparatus similarly available for remote control. In this equipment, the projectors throw their outputs on to a small camera, via an optical multiplexing unit. It enables miniature slides and small opaques to be shown rather after the fashion of the epidiascope.

The master control equipment supplied by Marconi’s provides for the simultaneous switching of sound and vision from eight input channels to two transmission channels, with adequate pre-viewing facilities. Two monoscope cameras provide the setting-up signals.

Lighting Equipment

Of particular interest is the fully remote-controlled lighting equipment supplied by Strand Electric. The control console, a remarkably compact piece of apparatus, allows the whole of the studio lighting set-ups and changes to be operated by one man.

Lighting plans are pre-set and single buttons on the console control a maximum of 10 lamps each, so that changes are achieved with the great flexibility and almost infinite variety required for the televising of continuous live shows.

Dimming is also dealt with from the same console, again on a pre-set system. Lamps (with the exception, of course, of the fluorescents) can be dimmed either individually or in combinations on an infinitely variable period change ranging from 2 secs. to 45 secs.

The control also has a “memory,” which means that lighting plans can be repeated as required.

Because of the sensitivity of the Image Orthicon cameras less lighting can be used than is common in film studios. The lamps themselves are mainly Mole-Richardson incandescents. There are, also, at present in use a number of banks of fluorescents, but it is planned to eliminate these as soon as possible because their narrow spectrum is inclined to give a “noisy” picture.

As the studio is being used for a combination of film and live TV, conventional cameras are necessary as well. To date, most of the film work has been shot on Cameflex, but this is to be supplemented by Mitchells.

Other equipment includes Vinter Pathfinders, Mole-Richardson and Debrie dolleys and M-R booms.

The programmes from the studio go by Post Office land lines to Associated Rediffusion’s headquarters at Television House, Kingsway, and thence to the ITA transmitter at Croydon.

The post In Nine Months TV Transforms Wembley Studios appeared first on THIS IS REDIFFUSION from Transdiffusion.

“Television is the art of instantaneously producing at a distance a transient visible image of an actual or recorded scene by means of an electrical system of telecommunication.”

The wording of the British Standards Institution’s definition of our work, gives a somewhat unimaginative description of an art form that has, perhaps, a most complex method of construction to produce small black- and-white shadows, yet also has a high degree of human attraction.

The first process in any television system the creation of an optical image of the scene to be transmitted. This optical image is formed in the case of cameras by the camera lens, and is focused by it on to the face of the pick-up tube inside the camera. It is then the function of the pick-up tube to convert the light image into an electrical current which varies in magnitude, in proportion to the amount of light reaching the tube from each part of the scene at any given time.

The exchange of light for an electrical current is the principle upon which a photographic exposure meter works. The tiny light-sensitive cell in an exposure-meter gives a small electrical current in direct proportion to the average light value of the subject which it is seeing and registers this visually on a scale.

This device, invaluable for photographers, is useless for television because it cannot convey information about the detailed structure of the scene. In the past many methods were tried, using the light-sensitive or ‘photo-cell’ as it is called, to break up the picture into small parts and to allow the photo-cell to look at one part at a time in strict sequence and to register a separate value of current for each. This is similar to the way in which the eye ‘scans’ a printed page, gleaning different information word by word and line by line.

Baird scanned his scene by means of an opaque rotating disc containing a series of holes in the form of a spiral placed in front of his photo-cell. The spiral was arranged so that, as the disc revolved, each hole in turn swept across the picture, allowing the photo-cell to see a small, continuously varying part of the scene. When the last hole had completed its scan across the bottom of the picture, the first appeared and started the operation at the top again. The current from the photo-cell was proportional at any instant to the amount of light reflected through the hole from the scene.

Another method reflected light from the scene by means of a revolving drum containing mirrors set on the outside in a staggered formation. When the drum revolved at high speed, each mirror reflected into the photo-cell light from a slightly different part of the scene each time.

These mechanical methods, however, suffered from extreme clumsiness of operation and poor definition because of their inability to scan the scene in small enough elements. A ‘major break-through’, as the popular press would now call it, was the innovation of a vacuum tube with electrical scanning.

This tube, rather like a large valve, was developed in this country in the early 1930’s and brought the first high- definition television system in the world into operation in 1936. The tube was called an Emitron or Iconoscope and was cumbersome, insensitive and, by today’s standards, somewhat crude in operation, but was in fact the parent of most present-day camera tubes.

In appearance it consisted of a cylindrical glass tube about 14 inches in diameter, one end of which blossomed into a bulb about 7 inches in diameter. The bulb had a flat window on one side and inside, parallel to the window, was mounted a ‘target’ upon which the optical image of the scene formed by the lens was focused. The tube joined the bulb at a slight angle and contained a device like a gun, which in effect fired a tiny stream of electrically-charged particles at the target.

This fine beam of charged particles called ‘electrons’, was made to sweep over the target in straight lines one below. the other, starting from top left of the picture through to bottom right and back to top left again. This sweeping or scanning could be achieved electrically at enormous speed and in fine detail because electrons are so small that they are almost weightless. At first sight this may appear to be unconnected with our original problem, which was the inability of the photo-cell to distinguish between the brightness details of a picture. In order to see in what way this can be useful, we must consider more closely the function of the target.

The target (so called because the optical image lands there as well as the electron beam) is made up of a sheet of mica covered on the front with a mosaic of many thousands of tiny photo-cells, each one insulated from each other and able to work independently. The mica sheet is then backed by a metal plate.

The situation is now that the optical image projected on to the target by the lens is not falling on one photo-cell but on many thousands so that each one is receiving an amount of light in proportion to the brightness of that particular element of the original scene. Part of our problem has, therefore, been solved, as the scene can now be divided into many small elements and each photo-cell can give a separate value of current.

As always, of course, there is a snag. What was an advantage at first sight now becomes a problem, because as soon as light falls on to the mosaic all the photo-cells merrily start to produce a current which they store rather like a battery. This current is not all required at once, and this is where the beam of electrons comes into its own.

As it scans the mosaic, it acts like a switch and touches each photo-cell in turn, causing them to discharge their stored current to the metal plate at the back of the target.

This current can be collected and forms the signal output of the tube representing at any given instant the discharged current of one photo-cell and, therefore, the electrical equivalent of one picture element. As this is changing extremely quickly there is a continuous output from the tube which is called the ‘video signal’. This signal is amplified and processed in many ways to become the transmitted picture, which when re-created by the receiver builds ‘a visual image of an actual or recorded scene…’ as in the definition.

This then was the first attempt at high definition tele- vision and many improvements followed fairly rapidly. Perhaps the most significant was the separation, in the pick-up tube, of the two functions performed by the target of electrical image creation and scanning. This was achieved by placing in front of the target a semi-transparent sheet having photo-electric properties which gave an electrical magnification and greater sensitivity. This type of tube was called an image iconoscope. The construction of the target was also modified to have a greater electrical storage, i.e. a larger battery, which was then scanned in much the same way as before.

These tubes were in use for a number of years and were in fact still used after the war.

Still further increases in sensitivity have been made and more efficient and complex tubes are now used by most television broadcasting organisations. The ‘image orthicon’ which is used for television broadcasting cameras, is perhaps the most versatile and widely used tube today. It has such sensitivity that in certain cases it will give a reasonable picture by moonlight. Its method of signal production does, however, differ from the image iconoscope but the same basic principles apply to both.

Another new tube, the ‘Vidicon’, is used extensively in telecine machines and industrial cameras and indeed some of the most significant developments of recent years have been in the field of vidicon tubes which, because of their small physical size and relative cheapness (£25 as against £450 approximately for an image orthicon), have been much favoured and will doubtless become increasingly useful in a wider field when certain fundamental snags are overcome.

Television cameras have many uses in fields other than broadcasting and one of the most significant has been their introduction into the field of medicine. Here, their use is obvious as a means of allowing many hundreds of students and nurses to view on closed circuit a major surgical operation, often in colour, which only a few at a time could normally watch in an operating theatre.

Additionally, because of their sensitivity under certain modified conditions of working, television cameras can be used to intensify an X-ray image in order to keep the ‘dosage’ of X-rays to a minimum for the patient while still providing a satisfactory picture under deep penetration conditions.

The use of television cameras in space-satellites is only just beginning and recent developments have been rapid indeed, as has been similar progress for the armed forces. So, from the humble photo-electric cell and Baird’s scanning disc of the 1920’s, has grown a world-wide industry employing many hundreds of thousands of people of varying skills which, I think it is fair to say, can give pleasure, entertainment, instruction and a means of research on a scale quite undreamed of even 30 years ago.

Of the future we can only make an intelligent estimate based on the rate of growth to date and the present state of the art and science.
That international exchanges of vision and sound will take place on a day-to-day basis and that trans-Continental networks will be available for world events is obvious from present indications.

That many future transmissions will be in colour and possibly stereoscopic as well would be a natural extension to the reality of today’s programming.

That more and more use of closed circuit viewing will be likely perhaps for specific programmes on a wired ‘pay as you view’ service, and eventually as an added facility to the telephone service.

Whether television could be made cheap enough for domestic use ‘See if junior is asleep in the nursery’ type of thing is debatable at present. Certainly a flat picture-frame type of viewing tube is possible and indeed in development at present.

That we shall explore, remotely at first, the outer edges of space and the depths of the oceans is again highly likely. In all these projects, however, the television camera tube has played and will continue to play a vital part in what is, perhaps, the most exciting medium of communications of our age.

The post How it works… Camera Pick-up Tubes appeared first on THIS IS REDIFFUSION from Transdiffusion.

John McMillan, general manager, was born in Sydney, Australia on January 29, 1915. He was educated at Scots College, Sydney, in which city he began work after leaving school.

He has successively been engineering draughtsman, magazine publisher, author, radio announcer, salesman, radio programme producer, gramophone record manager, film producer, soldier, sound broadcasting executive, television producer, programme controller and general manager. His first broadcasting job was on Station 2GB in Sydney. He emigrated from Australia to England in 1934 and joined the International Broadcasting Company Limited as a sales executive and later managed its programme production subsidiary – Universal Programmes Corporation Limited. After leaving that company he managed a gramophone recording subsidiary of Electrical and Musical Industries Limited and produced a film for Warner Bros. He joined the horse cavalry as a trooper and was later commissioned as an infantry officer in the 2nd Battalion The South Wales Borderers. In 1944 he was transferred to the War Office as a staff officer (Broadcasting). Subsequently he planned, mobilised and commanded No. 1 Field Broadcasting Unit which operated in north-west Europe and eventually established the British Forces Network in Germany.

On being demobilised in 1946 he joined the BBC as an assistant to the controller of the light programme and then became chief assistant until he resigned in 1952. He spent some time in American television and has been with independent television in this country from the beginning. He was general manager elect of Kemsley-Winnick Television and joined Rediffusion late in 1955. He became controller of programmes early in 1956, and general manager on January 1, 1964. He is now a citizen of the United Kingdom.

The post John McMillan appeared first on THIS IS REDIFFUSION from Transdiffusion.