Tele-snaps

A telesnap — or tele-snap — was a photograph taken by John Cura from the transmission of a televised programme. It was essentially a primitive form of recording transmissions in the days when the price of videotape was still prohibitive. Telesnaps allowed a cheap and portable way for actors, directors and other interested individuals to have a record of their work. In many cases, they became the only surviving visual record of monochromatic episodes that went missing from the British Broadcasting Corporation's archives.

Definition
Though John Cura didn't patent the process or trademark the term, the word "telesnap" specifically describes the work done by him, largely because his camera was unique, and his service of providing contact sheets of entire episodes was also unusual amongst people who provided a similar service at the time. Key to the difference between Cura's work and others was the fact that his camera took images at the speed of 1/25th of a second — the standard PAL framerate. Thus he was able to capture individual frames of programmes with each click, whereas his rivals, at least initially, couldn't. Thus their waste rate was much higher than his, meaning that he got a much higher percentage of "good" images of each show.

Beyond that, it is somewhat easier to further define the term in terms of what it is not:
 * It is not any off-air recording.  Thus, although images of the transmission of "The Feast of Steven" exist, telesnaps do not.
 * It is not a publicity still. Though Radio Times were known to have used telesnaps for publicity purposes, and this usage arguably turned John Cura into a kind of "accidental still photographer", they aren't what are generally thought of as publicity stills.  They were records of transmission, not stills taken during production for the express purpose of publicity.
 * It is not the same as a casual photograph taken by cast or crew members. Thus telesnaps are not images derived from, for example, the several 8mm home movies made of location filming.  Nor are they on-set images taken from a vantage point other than the one the recording video camera would have had.
 * In terms of Doctor Who, a telesnap is never in colour, as Cura died just before the beginning of the show's colour age.

History
In 1947 John Cura, a self taught man with a passion for electronics, sent a letter to the BBC offering his services of tele-snaps, still photographs taken at various intervals during the program's broadcast. His method was simple – a 35mm camera of his own design, pointed at a television screen, could take up to 80 such images during the broadcasting of the programme. Normally, Cura would take around 60 photographs for a half-hour episode and provide these on a contact sheet to the BBC. Cura stopped taking telesnaps with the fifth production block (which ended with The Mind Robber), which is why no telesnaps exist of the missing episodes of Season 6. No telesnaps exist from John Wiles's producership of Doctor Who (effectively from Galaxy 4 to The Ark), since Wiles was not enlisting Cura's services at the time.

Availability
Several of the groups of telesnaps have been published as blocks of episodes in Doctor Who Magazine, or been released in a compilation form with audio soundtrack on video, DVD or CD by the BBC.

Missing episodes with no telesnaps existing

 * Marco Polo episode 4
 * The Reign of Terror episodes 4 & 5
 * Galaxy 4 - all episodes
 * Mission to the Unknown
 * The Myth Makers - all episodes
 * The Daleks' Master Plan - episodes 1, 3-4, 6, 8-9 and 11-12. Twenty low quality and mostly very blurry images exist of "The Feast of Steven" thanks to the amateur efforts of actor  Robert Jewell — a Dalek operator who worked on The Daleks' Master Plan.  But these aren't quite the same as telesnaps. Jewell was apparently just pointing his off-the-shelf camera at the television screen and clicking. Consequently, all are blurry to one degree or another, and in no way rival Cura's work.
 * The Massacre of St. Bartholomew's Eve - all episodes
 * The Celestial Toymaker episodes 1-3
 * The Enemy of the World episode 4
 * The Invasion episodes 1 & 4
 * The Space Pirates episodes 1, 3-6