Film speed up.

[ppppenguin]

Silent film was shot at around 16 to 18 fps.  About the lowest they could get away with.  Sound needed 24 fps for the sound track. All this was before  TV. 

Some film for TV was shot at 30 which meant 50 hz  countries would have had serious problems before good standards conversion was readily available.

[DrStrangelove]

I recall being asked the film speed question in an interview at Pontcanna in Cardiff in 1982.

My answer (never having seen a telecine machine) was that the film runs at 25fps: this was deemed incorrect.

Having been on the VR2000 training course, I was offered the job, but decided it wasn't for me & turned them down.

[PerdioPal]

A bit like tape speeds, 30 inches per second form the Americans just after WWII, wish they started at 32IPS.

[colly0410]

Remember when I was a kid being at someone's house & they were showing old Charlie Chaplin & keystone Kops silent films & the flicker was horrid, being 16/18 FPS no wonder. When they were shown on TV in the 1960's they were sped up, I presume to 25 FPS. I thought back than that the speed up was for comedic effect, but more likely aunty Beeb couldn't afford or couldn't be bothered to use frame store gubbins...

[Mike Watterson]

USA got tape recording from Germany after WWII. They used wire or maybe steel tape before that.
https://www.analogsoundware.com/rr/aeg%2...etophon-k2
39.37 ips and first recorder with AC bias. The discovery of AC bias was made when a Magnetophon producing recordings of extraordinary quality was sent 'for repair'. The machine was found to have an oscillating DC bias amplifier. 1941. The quality was better than AM Radio.
AEG engineers made rapid strides in perfecting the system and had practical stereo recorders by 1943. Until 1945, about 250 stereophonic tape recordings were known to exist.
By 1943 quality far exceeded 78s
.
In the final stages of the war in Europe, the Allies' capture of a number of German Magnetophon recorders from Radio Luxembourg aroused great interest. These recorders incorporated all the key technological features of modern analog magnetic recording and were the basis for future developments in the field
https://en.wikipedia.org/wiki/Magnetophon

The 1944 German AEG K7 was stereo and Tape speed 77 cm/s = 30.315 IPS. Probably PVC tape.
The K8 was post war (1947) and 30 ips.
https://www.analogsoundware.com/rr/aeg%2...etophon-k8

Ampex was based on machines taken to USA from Germany.
No USA plastic tape machines before 1945, so 30 ips is based on AEG 77 cm/s
Bing Crosby hated studios & Holywood, hence invested in Ampex audio tape and later Video.

[Mike Watterson]

Film speed of 24 fps is alleged to be because of sound in 1927(?).
But why?
35mm was created by cutting 70mm stock in half and adopted by Lumière brothers. Eventually the US Government cancelled Edison's bogus patent.
Before sound the movie was shot as slow as possible to still give illusion, so 14 to 20 fps.
16 frames of 35mm for standard movie format is 12", so 24 frames is 24 x 1 2/16 = 18 IPS. But initial talkies used 33&1/3 versions of 78s, almost 16" and played from centre. This was for 11 minutes, or 1000 ft of 24 fps 35mm film.

The Jazz Singer in 1927 is often quoted as first "Talkie", though demos as early as 1900 and maybe 1923, they where short movies. The Jazz Singer was the first feature length and was still using sound on disk, though sound on film had been demonstrated years earlier.

It's more likely that the 24 fps is to do with a synchronous motor off AC mains to have a consistent speed or the disc and film would quickly go out of sync. However initially In sound-on-disc technology in the USA the 1920s, a record turntable is connected by a mechanical interlock to a specially modified film projector, allowing for synchronisation. Edit or repair of film was an issue!

Sound on film didn't need a mains-locked projection/camera motor or interlock with disc player.
Public showing in 1922 in Germany of sound on film.

Later film projectors showed each frame twice (rotating shutter?) to reduce flicker.

It's a pity HD wasn't progressive only and 72 or 96 fps at 1024, 1152 or 1280 lines. Having 4K at 24 fps is daft.

My theory is that sound and loads of theatres meant what ever had been chosen was fixed. Variable speed is problematic. They wanted as slow as possible to save film. Almost all was shot outdoors (indoor scenes created on 3 sided boxes on outdoor lots. So lamp flicker at 60 Hz wasn't an issue.
https://en.wikipedia.org/wiki/Sound_film

[Kalee20]

Remember when I was a kid being at someone's house & they were showing old Charlie Chaplin & keystone Kops silent films & the flicker was horrid, being 16/18 FPS no wonder.

It might have been an artefact of the projector used to show the films - if it was basically a sound projector with a 16fps speed included as an afterthought.

'Proper' showing of 16 frames per second film has a shutter giving 48 flicks per second, with the film pulled down every third flick - fewer than 48 inherently gives an unacceptable degree of flicker due to the limits of persistence of vision.

Yes, motion is slightly more jerky than 24 frames per second filming (which also runs at 48 flicks per second - the film gets pulled down every second flick). But it's only noticeable with fast-moving objects.

If you slow down a 24fps projector to 16fps without changing the shutter (such as a 2-blade to a 3-blade) you will get 32 flicks per second which is below the limit of acceptability.

[Kalee20]

Before sound the movie was shot as slow as possible to still give illusion, so 14 to 20 fps.

Don't forget also, the making of the film!

With 16fps, the maximum each frame can possibly be exposed is 62.5 milliseconds - allowing time for the camera shutter to blank off, and the film to be advanced for the next frame, the maximum exposure time in practice is quite a bit less than this.

This was a serious limitation due to film sensitivity. The only solution was to limit the number of frames per second, but in projection, show each frame more than once to reduce flicker.

By the time sound came along in the 1920's, photographic chemistry had advanced, improved film emulsions with more sensitivity were available, to the point that a new standard could be established - hence 24fps to be compatible with projector gearing etc.

[Mike Watterson]

Yes, sensitivity was an issue. Hence the outdoor filming.
Many startups fled New York because of Edison. But they went to bright open spaces. Hence Hollywood.

[ppppenguin]

There was a suggestion that the bbc couldn't be bothered to use frame stores in the 1960s. The first digital frame stores were made in the 1970s and were hugely expensive . Even in the 1980s they were not cheap. 

The bbc did design an analogue frame store in the 1960s. Used in the first electronic 525 to 625 converter. It used quartz delay lines. Right on the limits of technology and again horribly expensive.