What is the Phi Phenomenon?, What is the significance of 12fps?, What is over and under-cranking?, What impact did the introduction of sound have on frame rate?, Give as much rationale as you can for why 24 became the international frame rate standard?, What issues surrounded bandwidth? AND What is interlacing?

1. HISTORY OF FRAME RATE
What is the Phi Phenomenon?
First described by Max Wertheimer (1912), nothing in the movies are real,
from set to actors, even the essence of moving pictures. It is all an optical
illusion. The spinning circle of wheel isn’t actually moving but instead the dots
are taken of one by one and put back again and when the process speeds up it
looks as if the circle is moving around.
What is the significance of 12fps?
The human brain can perceive about 10-12 individual fps. Faster than that
our brains blend the images together into motion. Playing back 12 frames per
second with 12 intermittent period of black as the film advances it will create
an intolerable amount of flicker. In order to make the flicker disappear, and
according to Thomas Edison the magic number is 46 times per second.
What is over and under-cranking?
The inconsistency of silent film frame rates was a hassle for historians and
preservationists. Early cameras and projectors were hand cranked and
cinematographers will under-crank and over-crank the camera for effect.
Under-crank: Recording a slower frame rate than final projection, and over-
crank: recording a faster frame rate than final projection. D.W. Griffith was
notorious for under-cranking his shots, shooting as low as 12fps. Even Edison
ignored his own recommendation.
What impact did the introduction of sound have on frame rate?
The introduction of sound was one of the most drastic technological and artistic changes in all of motion
picture history. Since sound was recorded as an optical track that ran alongside the film strip, recording and
playing back film had to be kept at a very strict and even frame rate. That frame rate would be established
internationally in 1929 as 24 frames per second. However, the need for a consistent24 frames per second
was a major problem in the sound department. The first sound cameras with their whirling electric motors
were very noisy- forcing camera operator to shoot from a soundproof booth through a window.

2. Give as much rationale as you can for why 24 became the international frame rate
standard?
They found that the audio track just didn’t have enough fidelity on a 16 frames per second system. Utilizing
48 projected frames as our goal, they stepped up the next factor, utilizing a 24fps projection utilizing a
double bladed shutter to keep to desired 48 projected frames per second. 24 is a number that can be easily
divided by 2,3,4,6 and 8. So an editor can know right off the bad that half a second is 12 frames, A third is 8
frames, a quarter is 6 frames etc. It isn’t cheap and 24 frames was just the lowest easily divisible number
that would work for sound. It is almost culturally ingrained into what we come to expect from the cinematic
experience.
What issues surrounded bandwidth?
Television had the same problem, flicker issues that plagued motion picture film- yet flashing the same
frame on screen was not an option that was technologically achievable. Engineers were more concerned
about bandwidth, something they were trying to keep hold of over-the-air television broadcast. The solution
was developed solely by German Telefunken engineer Fritz Schroter in 1930 and in the US by RCS
engineer Randall C. Ballard in 1932. To conserve bandwidth and avoid flickering- each frame would be
interlaced.
What is interlacing?
Interlace is summarised into 2 fields- an upper and a lower field. Each field would be created on the screen
one after the other in a comb like patters. After the scan returns to the top and repeats (now scanning the
even lines), the two fields are then woven back together to make a full-frame image, hence the name
interlaced. It is also known as the letter “I” (as in 60i or 1080i), was picked for a lot of technical reasons that
have very little in relation to how we watch and shoot television today. The outcome of this decision left us
with a very crisp image that is laid down in an alternating order. Tis time the lines are scanned 1,3,5,7,9, etc.
into what is called a field. It reaches the bottom of the frame in half the time, meaning that if something is
moving very fast across the screen, interlaced will deliver a crispier picture, very much similar to a fast
shutter speed on a still camera.
BIBLIOGRAPHIES
 The History of Frame Rate for Film. (2015). [film] Directed by J. Hess. Filmmaker IQ.
 Reff,M. (2008). Choosing Your Direction: Progressive or Interlaced. [online] Videomaker.com. Available at:
https://www.videomaker.com/article/f6/13755-choosing-your-direction-progressive-or-interlaced [Accessed
19 May 2017].