Jesse Kalin writes:
>The background "flashing" (or flickering of light-darker-lighter...) seems
>ubiquitous in silent films as we see them today, even when well
>remastered. Is this an artifact of the originals, deterioration of the
>film stock, producing copies, ...?
Given that most studio cameras were hand-cranked until the conversion to
sound, there was sometimes a variation in exposure length between each
frame, especially at lower speeds (Griffith films shot by G.W. 'Billy'
Bitzer using the Pathé camera are a case in point). Most visible flicker,
however, is not so much an artifact of the originals but of the way they
are seen, either through a film projector or the telecine (film to video
copying) process. Before going any further we need to get to grips with
how the illusion of movement is created in film projection. Stephen
Herbert's essay at www.grand-illusions.com/percept.htm is a good place to
start, as is Joseph & Barbara Anderson, 'Motion Perception in Motion
Pictures' in Heath & De Lauretis (eds.), 'The Cinematic Apparatus'
(Basingstoke, 1981), pp. 76-95.
That lot having been digested, around 45-50 shutter movements per second is
generally considered about the minimum needed to produce the flicker-free
image of continuous movement using a conventional film projectors. Until
the 1920s most had three-blade shutters, that is to say a disc of metal
with three holes cut in it, between the light source and the screen. Each
time the third blade blocked the light source, the projector's intermittent
mechanism pulled down a frame. 3 x 16 = 48, therefore a shooting rate of
16fps was generally considered the minimum needed for the accurate
reproduction of movement in projector.
During the 1920s projector manufacturers gradually moved from three to two
blade shutters: the former absorbed more light, and the picture palaces
springing up with 1,000 seats or more and a long throw from projector to
screen needed all the light from their projectors they can get. If you
fall below those 45-50 shutter movements per second, you see a flicker. So
projection speeds in cinemas increased because of the two-blade shutters,
as a result of which studios were effectively forced to increase shooting
speeds. When 24fps was standardised for sound on film, the main reason was
that this was what most theatres were doing anyway.
Show a film significantly under 24fps with a two-blade shutter and you'll
see a visible flicker. For this reason arthouse and rep theatres which
regularly screen silent prints normally fit three-bladed shutters to their
projectors. But somewhere which shows the occasional one-off silent, or a
16mm print shown on a portable projector in a classroom, probably won't do.
There were similar problems with video transfers. Telecine equipment
designed for the PAL system (50hz) normally runs at 25fps and simply scans
each frame (both fields) twice. For NTSC (60hz) the so-called 3:2:2
pulldown is used, whereby some fields are scanned more often than others in
order to fit 60hz (which would be 30fps, i.e. too fast to get away with, if
you scanned each frame twice) into 24fps. Nowadays, computer-controlled
telecine and datacine equipment can transfer film at whatever speed and
into whatever system you like, but this wasn't the case until the early
'90s or so: before then, transferring at non-standard speeds also did nasty
things to the resulting image on the tape. For more on this see
Kallenberger & Cvjetnacanin, 'Film into Video: A Guide to Merging the Two
Technologies' (Focal Press).
A monumentally shameless plug: this and other related issues are covered in
my book 'Moving Image Technology: From Zoetrope to Digital', published by
Wallflower Press in April (US distribution from June:
admittedly in nothing like as much depth as in the work cited above.
So the short answer to your question is that in most cases, where flicker
is visible on a silent film viewed today, the equipment used to view it is
usually responsible: but not always or entirely. Until the conversion to
sound there was no standardised shooting or projection speed, with the
result that chaos reigned.
P.S. Many thanks to all who answered my 'Big Sleep' query. Affect it is,
by the looks of things. Having rechecked both definitions in Chambers, I
suspect that the many and often very subtle differences between US and
British English could have had something to do with my confusion.
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