BBC TV STUDIO OPERATIONS AND ENGINEERING - THE EARLY DAYS - Alexandra Palace and West London Television Studios

[The following is from my personal recollections of BBC Television during my working years on 405-line transmissions. I would like to thank 'Tony' Bridgewater OBE (former Chief Engineer, BBC Television), who has kindly verified the main facts of the story].

In BBC Television Operations and Maintenance department there were two types of jobs. Technical Operations or Maintenance Engineers. Engineers spent about six moths training in each section of Operations & Maintenance departments and usually opted to work mainly in Studio Apparatus and Control areas. After a qualifying period they were promoted to Studio Engineers or Telerecording and Videotape Engineers, eventually becoming specialists in their particular subject. A Technical Operator, however, had the choice of working with studio productions in either sound or camera operations or vision and lighting. This was not so in the early days of Alexandra Palace when nearly everyone was an engineer or technical assistant except the Producers and their Secretaries and the scenic operators.

The amplitude of the vision signal produced by the Emitron and Super-Emitron cameras was not directly proportional to variations in the incident light which formed the image on the photo mosaic plate as was originally thought. When the mosaic was scanned by the high velocity electron beam, large numbers of secondary electrons were displaced which bounced on to a collector electrode. To establish a balance the mosaic took more electrons from the cathode beam and this produced a spurious shading signal called 'fuzz' at the end of each line and at the bottom of each frame (field). This 'fuzz' was corrected by adding a combined sawtooth and parabolic waveform called 'Tilt & Bend'. Engineers who worked at Alexandra Palace told me that sometimes when the 'fuzz' was quite bad and could not be adequately corrected, viewers telephoned to say that "the footlights are showing very bright this evening and are in the bottom of the picture!"

The EMI Emitron camera control apparatus contained large numbers of valves, mounted on various chassis and assembled into racks 19"/20" wide and about 7ft high, with the tilt and bend waveform correction controls on the front panels. The vision engineers sat on fairly high stools and had to walk along the racks to make adjustments. Some of the adjustments at the top of the bays could only be made by standing and reaching up at arms length. As there wee always quite a number of continuing picture corrections, two people per rack (camera) were required. The rack engineers acquired a high degree of skill for judging picture quality as well as an ability to quickly compromise the settings as the picture changed. The engineers were referred to as 'Rack Operators' or simply 'Racks' (due to the racks of equipment they operated), and this name remained in use right through to the late 1950/60's. Another name which came with Alexandra Palace was the use of the term 'Gallery' for the production control areas. This was because the approach to the vision mixing desk and the monitors was by a steep wooden open stairway to a level about 10ft above the apparatus racks.

Although I was not in the BBC during the early days of Alexandra Palace, I did get a change to try out the old Emitron racks and tile and bend controls during breaks in rehearsals for a programme in 1954 to say "Goodbye to Alexandra Palace". The programme was made using cameras from an Outside Broadcast unit (MCR9) parked on the terrace by the side of the tower. A contribution to the programme was an excerpt from a well know play about world ear one, called Journey's End, transmitted live, of course, from Studio A using the Emitron cameras. Then over to the O.B. cameras in the restaurant, where Leslie Mitchell interviewed a number of celebrities who had appeared on television from A.P. in the pre-war days. Although the old Emitrons were at the end of the useful life, and due to be scrapped, the A.P. studios were taken over by BBC Television News and reopened a few weeks later. A BBC news film service had been operating, producing a bi-weekly high quality film newsreel for some years but there was now a change of policy and a live daily newscast with captions and slide inserts was planned to take its place. A small team of newsreaders was recruited and the studios were re-equipped with Pye P.E.S. photicons*

On the occasion of the "Goodbye A.P." programme the camera control units of the O.B. Image Orthicons were operated as usual by engineers. Two senior engineer/rack operators were responsible for the line up of and transmission picture quality of three or sometimes four camera channels whilst supervising an assistant. This was a normal procedure for O.B. working and allowed trainee engineers (like myself) the chance to gain valuable operating experience.

Due to variations in the sensitivity of early Image Orthicon tubes the 'f' stop of the lenses, for optimum picture exposure, were often very different from camera to camera. Two senior BBC engineers, Don Brothers and Ben Palmer, headed a small team who researched and devised a camera line-up procedure and test slide so that the standard sensitivity of all cameras would be within ½ 'f' stop and require only 5% adjustment of lift and gain. A special slide which contained a relevant part of test card C was made for the camera diascopes and if the cameras did not reach the required specification the Image Orthicon tubes were sent back to the manufacturers. (The Image Orthicon's were valued at and insured for £500 to £1000 each - quite a sum in 1950 - and hired and paid for per hour used). The standard Brother/Palmer method of lining up the camera channels was followed by all London television studios in the late 1950's and used with all the new Image Orthicon 4 ½" camera channels.

The television technical operations department was also re-organised in the mid 1950's with a number of new jobs called Vision Operator, Vision Supervisor, and Lighting Supervisor. The production department realised that studio lighting was a very important contribution to the success of a programme and the Head of Programmes encouraged the idea of a separate control area for lighting, with a control console operated by the lighting supervisor. The intensity of the studio lamps could be adjusted whilst observing the picture on the studio monitors. The Camera Control Units and operators were separated from the lighting control at this stage in a cubicle alongside. BBC Riverside studios control areas were designed in this way and it was found by experience that, although satisfactory, some 3 to 4 engineers/operators were required. In the early 1950's the matching of pictures from different cameras was achieved by adjustment of controls such as Lift and Gain, and lens Iris. However, only the very latest types of camera had remote control of the Iris. With a fixed 'f' stop the adjustment of lift and gain was insufficient to deal with many of the wide variations in the lighting contrast and as a next step all camera channels were modified and rewired to allow the operation of the lens iris and the CCU Lift and Gain (5%) by remote control. These controls were grouped on a panel in front of high grade monitors (usually 14" Pye 2780), in the Lighting control gallery. This was also tried out at BBC Riverside studios, Hammersmith, and proved so successful that the ideas were incorporated into the new studios installations at Television Centre. After the Television Centre opening programme from Studio 3 in 1960, the vision operational set up became known as "One Man Vision Control". Although only one operator was needed to operate the remove controls of Iris/Lift/Gain for all four or five cameras, (4 cameras were normal with five for the larger studios), two engineers were constantly checking settings of pre-set 'pots' (electrical focus and dynode volts etc.), on the CCU's in the apparatus room.

The success of this standard camera line-up and the 'one man vision control' operation soon spread to all BBC studio centres and was tried with all 4 ½" Image Orthicon cameras. As a result the quality of pictures from Image Orthicons was much more satisfactory and consistent. Control of the settings of studio lighting was another major factor which helped towards the improved quality of pictures. The high standard of black and white picture quality with a contrast and grey scale close to that of photographic prints and cinema film was maintained and continued well into the late 1960's. 'One man vision control' became firmly established for operation of cameras for the BBC 2, 625-line service, but with the coming of colour television, a standard camera line-up could not be devised for the 3 and 4 tube plumbicon camera channels for some time. The correct spectral response of the prism used for splitting the colour image into the primary red, green and blue, and luminance signals had to be carefully examined first, and an investigation into this was referred to the BBC Research Department. In the case of the later EMI 2001 colour camera it meant that many of the colour camera colour prism wedges were returned to the factory for modifications.

[First published in '405 Alive', an independent, not-for-profit magazine, devoted to the study of old television technology and programming. ISSN 0969-8884].

Larry Coalston