Please note that this website is still a ‘work in progress’ and that a definitive version will not be available until the end of 2020. Until then all posts should be regarded as provisional and subject to correction or development.
Film types and gauges
Film speed and duration
Film speed in the silent cinema era is the subject of an excellent article by Kevin Brownlow (1980)
- a) film speed in the camera
- b) film speed on projection
- c) the change from 16-18fps to 24-25fps
- d) the relationship between physical length and duration
- e) adjusting for frame rate when transferring to video
- f) ‘la remise à cadence’ – adjustment for speed when calculating duration in video
A website providing a very useful table for converting physical length into duration can be accessed here
There are various useful discussions on the web of issues related to frame rate, including this one.
From the 1920s, cameras driven either by spring-wound clockwork mechanisms or even by electric motors began to appear. However, cameras with electric motors were not only very expensive, but they also required a power source. In remote locations, this usually meant a very heavy battery as well as a generator to charge it.
While some commercial travelogue film-makers started to use cameras with electric motors as early as the 1920s, most ethnographic film-makers went on using clockwork-driven cameras until the 1950s, when batteries eventually became light and stable enough to be easily portable.
Although the clockwork motors represented a considerable improvement on hand-cranking, they also had their own problems. One of these was that the maximum duration of a shot was limited to 20-25 seconds, which was the time that it took for the spring to unwind. Also, as the spring came towards the end of its unwinding, the film began to move through the gate more slowly, which in effect speeded up the movements when the film was projected.
Even if the effect was relatively minor, it was this incapacity of the clockwork-driven motor to maintain an absolutely constant speed that undermined early attempts to achieve perfect lip synchronicity.
The early years of the sound recording industry in the last quarter of the nineteen century were characterised by fierce competition between two competing technologies, one of which was based on recording onto wax-coated cylinders, the other onto flat discs.
By the early years of the twentieth century, this competition had largely been resolved in favour of discs. Although the quality of the recording may have been higher on cylinders, the maximum length of the recording time on discs was significantly greater and they were more easily reproduced and stored. By this time also, ‘gramophone’ was starting to replace ‘phonograph’ as the most commonly used term to describe a machine capable of reproducing sound.
While some early ethnographic film-makers used cylinder-based recorders others, used disc-based models. In 1929, the Photophone optical sound system, which involved recording sound, via a mixer, onto the same film negative onto which the images were being captured, was launched by RCA Victor (see below). But this system was complex and very expensive and used only by commercial travelogue film-makers.
- a) wax-cylinder phonographs
- b) the disc-based Archiv-phonograph
- c) Photophone system
- d) wire recorders
- e) tape recorders
Specialist Technical Terms