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Frequently
Asked Questions
Version 5
31st Jan 1998
| Q01 | Test Card, Test Chart, Test Pattern, what is the correct name for these images? |
| A | In the early days of television, there was a need to test the response of cameras then in operation. This was done by use of a special pattern, drawn on to a large piece of card, which the camera then pointed at. Hence the name "Test Card". In the UK, this name has stuck despite most of the patterns now being produced by other means, either transparencies, monoscope or electronically generated. North America has tended to use the term "Test Pattern". Very early, simple patterns used in Britain were sometimes known as "Test Graphs". Test Cards were often 3ft wide, to enable lots of detail to be drawn in. Later versions used clever photographic techniques to produce the final result. |
| Q02 | What is a monoscope? |
| A | They were popular in the forties and fifties,
particularly in North America. They were a camera tube,
with a fixed image built in to the end. The image was
etched on to a metal plate and could not be changed once
manufactured. The process meant that only black and white
images were possible, no greyscales. By using lots of
alternate black and white lines, an illusion of grey was
possible. They are not used today. |
| Q03 | What is a transparency? |
| A | The use of "opacities", or cards relied on
reflected light being received by a camera. This created
problems as the image varied depending on lighting
conditions and shiny reflections could also appear
depending on the card and camera position. Transparencies
relied on a sheet of film being placed in front of a
light box, in much the same way that X-Ray photographs
are viewed by doctors. This gave a constant image that
could be used as a reference point for testing the other
equipment. Early transparencies were quite large, to
enable high resolution. Modern transparencies are still
used and are typically the same as the 35mm slides that
are in common use. |
| Q04 | What is meant by "Electronically Generated"? |
| A | Most modern day test cards are electronically
generated, using a special box of tricks that produces
the correct video signal without the need for a camera.
This is typically done by storing the desired image in a
professional standard graphics file either in
non-volatile memory or on a CD ROM. This method ensures
that the resulting signal is identical every time. |
| Q05 | What was the first electronically generated test card? |
| A | Older than you may think! In 1937, Baird produced the
"Art Bars" (artificial bars), which consisted
of a thick black cross on a white background. I do not
know what equipment was used to generate this. The BBC
have had an electronically generated test card since
1971, when the Phillips derived Test Card G was
introduced. The BBC switched to the modern electronic
Test Card F in 1984. |
| Q06 | What was the first British Test Card? |
| A | There are several possible answers to this, depending
on your definition of test card. Baird had a simple
circle and line chart for testing picture ratio in 1934.
BBC Test Card A made it debut in the 1940s. Test Card D
was the first test card to be produced to an engineering
specification in 1964. |
| Q07 | When did Test Card F arrive? |
| 1967. It was the BBC's first colour test card. | |
| Q08 | Who is the girl pictured in Test Card F? |
| Carole Hersee, daughter of George Hersee who led the design of the card. | |
| Q09 | Is it true that Carole is left handed? |
| No. Although it has been widely reported that Carole was left handed, this now appears not to be the case. The final picture was reversed, and George Hersee previously stated that this was because Carole was holding the chalk in her left hand. This led to the conclusion that Carole was left handed. However George wrote to the BBC in house magazine, Ariel in March 1997 stating that Carole has never been left handed, and that the reversal of the transparency was to correct an earlier accidental reversal. | |
| Q10 | Why the noughts and crosses board? |
| They wanted a marker to indicate roughly the centre of the card for static convergence tests. The X on the noughts and crosses board is there for that reason. | |
| Q11 | Why was Test Card E dropped so quickly? |
| There is some confusion as to how long Test Card E lasted. George Hersee the BBC expert on Test Cards is reported to have said it was withdrawn on the first afternoon, having been shown in the morning. Other informed sources say it was shown for up to a month before being withdrawn. The objections were from the TV trade and were related to the us of sinusoidal frequency gratings, instead of the previously used "square" wave gratings. The sinusoidal gratings were ideal from an engineering viewpoint, producing a good signal to measure. However they appeared on most sets to be out of focus, leading to complaints. | |
| Q12 | When will the BBC release the next Test Card? |
| Possibly never. Test Card F is now 30 years old and still in use around the world. If / when widescreen TV gets off the ground, possibly as part of digital terrestrial TV, then a widescreen testcard may appear. Philips already have one and it may be that this will be modified. However for standard 4:3 ratio television, there does not appear to be a need for a new test card. Of course the captions will change next time there is an ident change as happened on 4th October 1997. Test Card G still makes an occasional appearance overnight, as can be seen in the Test Card Gallery, and recently an unusual and as yet unidentified test card has appeared on BBC2. | |
| Q13 | When can I see BBC Test Card F? |
| Around the clock television means that the Test Card
cannot be seen very often. Channel 4 and ITV are now 24
hours, which means we have seen the last of the IBA
originated ETP-1. Test Card F is currently broadcast on
BBC2 early on Saturday and Sunday mornings between the
end of the Learning Zone and the beginning of programmes.
It is replaced by Ceefax pages fifteen minutes before
programmes start. The BBC satellite services are also 24
hour, so no test card is shown there. I would like to know where Test Card F has been used abroad, so drop me an email if you have seen TCF in your country. |
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| Q14 | What can you tell me about early test films? |
| "The Home Made Car", "Skyhook", "Boat '66", "Paint", "The North Sea Quest", "Divertimento" are just some of the films made by independent companies and shown on the BBC in the sixties as part of the Trade Test Transmissions. They were shown for a couple of simple reasons. There was a shortage of high quality films (particularly in colour) and they were free to show. I might be able to produce a feature on this subject if you send me your memories. | |
| Q15 | My question was not listed here, where can I find the answer? |
| Email your questions to darren@meldrum.co.uk
and I will try to find the answers! Or join the mhp-chat mailing list where others may be able to help. |
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Last Update 01 Apr 1998