Aspect ratio

An aspect ratio is the ratio between the dimensions of an image. The history of Doctor Who and its related properties features a variety of examples, drawn from different formats used to produce the visual components of its stories.
From inception, the show used both film stock and videotape to obtain footage for broadcast. At the time, each medium was widely employed to produce images of a 4:3 (1.3':1, sometimes known as fullscreen) ratio, as it was natively supported by the standard formats of the respective media. This material could then be broadcast to view on television sets which also followed this industry standard.
An exception came in the form of the 1960s Amicus Productions movies, which utilised a format called Techniscope. This method used 35mm film stock at a different perforation interval, allowing for a naturally wider, if considerably smaller, image for each frame. The resultant aspect ratio of 2.33:1 was then resized by optically warping the image to the cinema standard of 2.35:1.
Until the beginnings of the BBC Wales series, no material for the show had ever been shot, much less broadcast, in a form outside the standard fullscreen. However, with the growing presence of digital video photography and broadcast, and the now distant practices of filmmaking, the industry standard for television had undergone significant change while the show had been off air. With its return, a new period began, dominated by digital video acquisition produced in the increasingly popular 16:9 (1.7':1, often termed ) ratio and broadcast to screens much the same. This practice was preserved across several spin-offs and throughout a great many shifts in the technical dimensions of production, seeing out a variety of cameras and video formats.
In 2018, a new normal was established. With use of anamorphic lenses for the first time in the show's history, the programme adopted a 2:1 aspect ratio (often branded Univisium, after a related industry proposal) for its image. While it is possible that some corresponding shift in screens was on the horizon, the diversity of means of media consumption that had obtained contemporaneously offered an alternative approach to making the change, following suit with the emergent practices of many s of the time.