The EMI

EMI

The EMI Group, also known as EMI Music or simply EMI, is a multinational music company headquartered in London, United Kingdom. It is the fourth-largest business group and family of record labels in the recording industry and one of the "big four" record companies. EMI Group also has a major...

 2001 Broadcast studio camera was an early, very successful British made Plumbicon studio

Television studio

A television studio is an installation in which a video productions take place, either for the recording of live television to video tape, or for the acquisition of raw footage for post-production. The design of a studio is similar to, and derived from, movie studios, with a few amendments for the...

 camera

Camera

A camera is a device that records and stores images. These images may be still photographs or moving images such as videos or movies. The term camera comes from the camera obscura , an early mechanism for projecting images...

 that included the lens

Photographic lens

A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.While in principle a simple convex lens will suffice, in...

 within the body of the camera. Four 30mm tubes allowed one tube to be dedicated solely to producing a relatively high resolution monochrome signal, with the other three tubes providing red, green and blue signals. Even though semiconductors were used in most of the camera, the highly sensitive head amplifiers still used thermionic valves

Vacuum tube

In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

 in the first generation of the design.

Integrating the lens within the body of the camera had both positive and negative effects. On the positive side, it meant the optical nodal point of the camera was close to the centre of gravity, which could make operation easier and more instinctive when used on movable camera mounts such as pedestals. The downside was that lens manufacturers were limited to which lenses they could adapt to fit to the camera. This made the 2001 less attractive for outside broadcasts.

The 2001 was both heavy and large. The pull-out handles at each corner needed four people to safely move the camera with the lens in place. It also required a separate remote camera control unit and the cable connecting the two was over 2 inches thick. The standard servo

Servomechanism

thumb|right|200px|Industrial servomotorThe grey/green cylinder is the [[Brush |brush-type]] [[DC motor]]. The black section at the bottom contains the [[Epicyclic gearing|planetary]] [[Reduction drive|reduction gear]], and the black object on top of the motor is the optical [[rotary encoder]] for...

 controlled studio zoom lens

Zoom lens

A zoom lens is a mechanical assembly of lens elements for which the focal length can be varied, as opposed to a fixed focal length lens...

 had a 5 to 50 degree horizontal angle of view, with a minimum focus distance of either 36 inches (J type) or 18 inches (K type)

First produced in 1966, by the early 1970s almost all of BBC Television

BBC Television

BBC Television is a service of the British Broadcasting Corporation. The corporation, which has operated in the United Kingdom under the terms of a Royal Charter since 1927, has produced television programmes from its own studios since 1932, although the start of its regular service of television...

's studios and many outside broadcast (OB) units were equipped with the 2001. Several ITV companies purchased or leased the camera including Thames

Thames Television

Thames Television was a licensee of the British ITV television network, covering London and parts of the surrounding counties on weekdays from 30 July 1968 until 31 December 1992....

, Yorkshire Television

Yorkshire Television

Yorkshire Television, now officially known as ITV Yorkshire and sometimes unofficially abbreviated to YTV, is a British television broadcaster and the contractor for the Yorkshire franchise area on the ITV network...

, ATV

Associated TeleVision

Associated Television, often referred to as ATV, was a British television company, holder of various licences to broadcast on the ITV network from 24 September 1955 until 00:34 on 1 January 1982...

, Granada

Granada Television

Granada Television is the ITV contractor for North West England. Based in Manchester since its inception, it is the only surviving original ITA franchisee from 1954 and is ITV's most successful....

, HTV

HTV

HTV, now legally known as ITV Wales & West, is the ITV contractor for Wales and the West of England, which operated from studios in Cardiff and Bristol. The company provided commercial television for the dual-region 'Wales and West' franchise, which it won from TWW in 1968...

, Anglia

Anglia Television

Anglia Television is the ITV franchise holder for the East Anglia franchise region. Although Anglia Television takes its name from East Anglia, its transmission coverage extends beyond the generally accepted boundaries of that region. The station is based at Anglia House in Norwich, with regional...

 and LWT

London Weekend Television

London Weekend Television was the name of the ITV network franchise holder for Greater London and the Home Counties including south Suffolk, middle and east Hampshire, Oxfordshire, south Bedfordshire, south Northamptonshire, parts of Herefordshire & Worcestershire, Warwickshire, east Dorset and...

. Independent outfits such as the early cable television

Cable television

Cable television is a system of providing television programs to consumers via radio frequency signals transmitted to televisions through coaxial cables or digital light pulses through fixed optical fibers located on the subscriber's property, much like the over-the-air method used in traditional...

 stations Rediffusion Cablevision, Sheffield Cablevision

Sheffield Cablevision

Sheffield Cablevision was a cable television community channel in Sheffield, England which launched on 29 August 1973. The channel was one of five community cable television experiments were authorised by the UK's Minister for Posts and Telecommunications in 1972. It was on the air every night from...

  and the educational television arm of the Inner London Education Authority

Inner London Education Authority

The Inner London Education Authority was the education authority for the 12 inner London boroughs from 1965 until its abolition in 1990.-History:...

 also purchased the camera.

Although there was no predicted lifespan for the camera, the heavy hot-running four-tube design was considered somewhat outdated even when it was new, which contributed to the camera's near-total failure to sell to broadcasters outside the UK. Several ITV companies had begun replacing them in the late-1970s with the last commercial operator (Yorkshire) phasing them out in 1982. However the BBC kept a number of such cameras in operation at their Elstree Studios

Elstree Studios

"Elstree Studios" refers to any of several film studios that were based in the towns of Borehamwood and Elstree in Hertfordshire, England, since film production begun in 1927.-Name:...

 until 1991; they were kept going by cannibalising identical cameras left behind by ATV when the BBC purchased Elstree from them.

The EMI 2000 (as it was originally called) that was originally tried and tested by the BBC in 1967 used 30 mm integral mesh lead-oxide vidicons (vidicons are the tubes made by RCA

RCA

RCA Corporation, founded as the Radio Corporation of America, was an American electronics company in existence from 1919 to 1986. The RCA trademark is currently owned by the French conglomerate Technicolor SA through RCA Trademark Management S.A., a company owned by Technicolor...

) They were re-released a year latter using Plumbicons (Plumbicon is the trade mark for Philips lead-oxide tubes) It also used a themionic valve for the first stage of the video head amplifier. Unfortunately, the BBC technicians were disappointed by the picture results produced by the original testing model supplied to them in 1967. So disappointed in fact that they hesitantly bought 17 Marconi

Marconi Company

The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...

 Mk VIIs in order to commence colour broadcasting on BBC2 on 1 July 1967 as the redesigned and re-named EMI 2001 would not be ready for the colour launch date on BBC2. EMI re-released the re-named 2001 (now with the option of separate mesh tubes, either Plumbicon or Leddicon (tubes made by EEV

English Electric Valve Company

The English Electric Valve Company or EEV, is a specialist component and sub-system designer, developer and manufacturer. As e2v it has 6 European and US manufacturing facilities and its HQ in Essex, England....

) and solid state (FET

Fet

Fet is a municipality in Akershus county, Norway. It is part of the Romerike traditional region. The administrative centre of the municipality is the village of Fetsund.Fet was established as a municipality on 1 January 1838...

) head amplifiers) in early 1968 and the BBC moved their Marconi

Marconi Company

The Marconi Company Ltd. was founded by Guglielmo Marconi in 1897 as The Wireless Telegraph & Signal Company...

 Mk VIIs to the weather, news and presentation studios from TC7 and TC8 in Television Centre

BBC Television Centre

BBC Television Centre at White City in West London is the headquarters of BBC Television. Officially opened on 29 June 1960, it remains one of the largest to this day; having featured over the years as backdrop to many BBC programmes, it is one of the most readily recognisable such facilities...

.

When sold abroad, the EMI 2001 was carried under the Thomson SA

Thomson SA

Technicolor SA , formerly Thomson SA and Thomson Multimedia, is a French international provider of solutions for the creation, management, post-production, delivery and access of video, for the Communication, Media and Entertainment industries. Technicolor’s headquarters are located in Issy les...

 brand - hence "Thomson 2001". How this came about is unknown as EMI and Thomson SA did not have business links. The Thomson 2001's, like the EMI's, also used Plumbicons; however, due to a brochure which was printed in French

French language

French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

, it was presumed that they used Vidicon tubes. But, apart from the silver viewfinder squares (instead of white) and the brand name change on the front and sides, the cameras were the same. In the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, the cameras were marketed by International Video Corporation

International Video Corporation

International Video Corporation, or IVC, was a California company that manufactured several models of low to middle-end videotape recorders, or VTRs, for industrial and professional use. Their products were quite popular in the industrial and institutional markets.- IVC 800 series 1 Inch VTR :IVC...

as the IVC/EMI 2001-B (four tubes), with another version, the IVC/EMI 2001-C, consisting of three tubes.

Generating the image

Unlike most colour tube cameras of the period, which combined the output from three colour tubes at the same stage before the signals left the camera and made white light by combining the output from all three colour tubes, and the Marconi MkVII, which added the output of the three colour tubes to the output from the luminance (black and white) tube, the EMI 2001 took the output of the green tube as a starting point for the picture, added the colour from the red and blue tubes and then added the output from the luminance tube. Unlike the others, the luminance tube in an EMI 2001 wasn't used for taking white light, but it was used for the sharpness and fine picture detail of whatever object was the subject to be taken.

This image was electronically added on top after the output from the red and blue tubes was electronically added to the green one.

This was the part of the camera's design that was designed by BBC engineers, as they realised that the most natural colour could be achieved this way.

Comet tails

A very common artifact of early vacuum-tube cameras was a "comet tail". This is where a bright light or anything white builds up so much charge on the imaging surface of the camera tube that the charge cannot be removed in one "field" (1/25 of a second, the rate at which television pictures are made on PAL and SECAM broadcast TV systems). So when the camera is moved, the object causing the overload is moved, or something moves between the camera and the bright light source it causes a bright streak of where the source of the image flaw was. This is because that particular picture element on the camera tube's imaging surface is supposed to be imaging a dark surface, but it still has electric charge on that picture element and is read by the camera circuitry as light instead.

Most models of colour television camera had ACT (Anti-Comet tail) circuits for each individual camera tube and if they are not matched precisely, the comet tails appear to be coloured rather than white. The EMI 2001s didn't have ACT circuits. This means it is often very easy to tell if a programme used EMI 2001s (or any other first-generation PAL colour camera) to capture the images as the comet tails would often be coloured "blobs" or "splodges" (usually caused by a light source or light reflecting off a highly reflective or polished surface) simply because the camera did not have ACT circuits, but some were later modified to include ACT circuits. The ACT circuits were adjusted so that the Comet Tail doesn't appear to be a "blob".

Another artefact about the comet tails produced by the 2001s was that sometimes the comet tails would either be a mix of two separate colours, one colour inside the other (e.g. a comet tail that is red with a smaller comet tail inside that one that may be green). This is where both of the (in this example) red and green ACT circuits are not to the same adjustment of the other two tubes, but are adjusted at different levels themselves. In other cases, comet tails have been produced by 2001s that are not primary colours of light, e.g. pink. This is where the adjustments of both of the (in this example) red and white tubes are not adjusted to the same adjustment of the blue and green tubes, but are both themselves placed at the same adjustment.

ACT and the EMI 2001/1. As supplied by EMI the 2001 and the later 2001/1 did not have any form of ACT (anti-comet tail) or HOP (highlight overload protection). This is why its performance was poor, in this respect, when compared with the next generation of cameras supplied in the 1970s. None of the first generation of true broadcast cameras in the middle to late 1960s had ACT, so the EMI 2001 was not unusual.

While some broadcasters may have modified their cameras to have ACT, retro fitting ACT/HOP was not an easy modification as 4 new HOP camera tubes would be needed, the tube bases, wiring harness, 4 head amplifiers and 4 video amplifiers and the tube beam current boards would all have needed work done to them. ACT and HOP works by using an extra electrode in the tube to 'flood discharge' the target during the flyback period. Great care was needed in setting up the HOP voltages as damage to the tube’s emission could occur.

There was another method, ABO or DBO (Dynamic Beam Optimisation) that worked by measuring the tubes output and if it is more than a pre-set level above peak white, increasing the beam current in proportion. This DBO method could be used with standard tubes. If this is not implemented well it can lead to positive feedback, with loss of picture and damage to the tubes.

External links

• BBC Tech Ops History Site
• Museum of the Broadcast Television Camera
• The website of Martin Kempton on London television studios contains much on the industries use of various cameras over the decades, including the EMI 2001.