Monday 27 March 2023

Countdown to 60: Colour Separation Overload


No.19 sees us finally reach the 1970's, and the arrival of colour episodes...
Throughout the 1960's monochrome years, one particular effect that was used many times on Doctor Who was that of inlay. This was first seen in only the fifth ever episode - when the time travellers observe the Dalek city on the horizon. Two cameras were employed - one looking at a model, and the other at the actors on a practical set. This set would feature a section of black drapes. This would be masked off, and the model scene inlaid in its place. As such, the two elements had to be carefully positioned on either side of the screen. If you watch The Keys of Marinus, you will see that characters stand off to the side against a black background before disappearing with their travel dials.

With the advent of colour television, new techniques could be employed. Chief of these was a process known as Chroma Key - or Colour Separation Overlay as the BBC specifically termed it.
It's a similar process to inlay in that it employs the merging of the output of two cameras. Again, one is concentrated on a practical set, whilst the other is pointed at a set covered in a particular colour material. Initially this was blue, but when director Paul Bernard worked for the BBC after a spell with ITV he recommended yellow. (These days the process is known as green screen, as that is the usual colour).
A person or object placed on the coloured set could then be superimposed onto the practical set - the camera being keyed to ignore the CSO colour. The process wasn't perfect. CSO artefacts would often have a halo of the CSO colour around them. If the CSO colour featured anywhere on the practical set it would be rendered invisible. Reflective objects (like Giant Robots) would pick up the CSO colour and so have parts of them go invisible.

Despite the complexities and problems, CSO was embraced by some at the BBC - and one of its biggest advocates was Barry Letts, recently appointed producer of Doctor Who. He actually produced a training video to demonstrate its benefits. With the very first colour Doctor Who being produced on film due to industrial action, CSO first featured in the series in the second story - The Silurians.
In this we get a couple of sequences where the Silurians employ a scanner device which has images projected onto it - an Orangutan, the Silurian city and Major Baker.
One scene of note is when the Doctor and Liz Shaw encounter a dinosaur in the Silurian shelter. A full size costume was created, occupied by Bertram Caldicott of the VFX Dept, who usually ran the stores. (The dinosaur was nicknamed "Bertram the Friendly Monster"). 
This costume was so bulky and heavy that it had to have a metal ring attached to the head, so that it could be held upright by a chain connected to the gantry above. Pertwee and Caroline John stood on one set, which had a blue screen set up in a doorway. Caldicott was on another set depicting a cavern in his dinosaur costume. He was then superimposed onto the blue screen, resulting in the Doctor and Liz seeing a massive monster beyond the doorway.
It was only later that Barry Letts realised that they hadn't needed to go to the trouble and expense of making the full size costume and employing someone to fill it. A small puppet would have done the trick just as well for less time and money. Such was the learning curve with this new technology.

Another champion of CSO was director Michael Ferguson, who was due to direct the next story - The Ambassadors of Death. He and Letts ran an experimental session, looking at what CSO could do. One trick, which didn't really work out, was to slowly cover someone in blue polystyrene pellets, so that it looked as if they gradually vanished. 
A CSO sequence of note in this story was the arrival of the Doctor inside the alien spaceship. One camera was trained on the Perspex model interior, whilst the other covered Pertwee and the Recovery capsule on a blue set, accompanied by a forklift truck which had also been painted blue and thus rendered invisible. Pertwee stepped onto the forklift and appeared to float to the ground in the composite image. It is notable that there is no dialogue in this scene, as the forklift made too much noise.

Barry Letts then got to direct a story of his own - Terror of the Autons - and he basically went CSO-crazy. 
Not only did he use it for scenes similar to those mentioned above, but he dispensed with whole sets in order to CSO characters onto photographic backgrounds - a museum guard, the Master creating the Autons, and Mrs Farrell in her cavernous kitchen. The technique failed to work as there were problems of scale or perspective or both.
Used sparingly, CSO could be effective - but there are many instances throughout 1970's Doctor Who where it is very hard to suspend disbelief. Graham Williams decided to start filming models in the video studio then using CSO to place them on their backgrounds, which was far inferior to the old proper filming of model work. Things reached their nadir when rampant inflation meant that the cavern sets for Underworld could no longer be afforded - and a decision was made to use CSO and model caves.
The alternative was to cancel the production. Maybe that ought to have been the right decision...

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