At UCLA, in their newly opened Film Department, within the Theater Arts department, the issue was 'how effective is one single frame cut into a film?' It was determined that ONE FRAME within a film could be perceived in the telling of a story. Which is to say, we can (read may be able to . . .) perceive with content recognized one single frame in a film.
This is quite a different situation. An image can be flashed onto a screen for a very short time (a microsecond?) and we can, under certain conditions, have a pretty good idea of what the subject of the image was. Interspersed among a "flowing" series of images (like a movie) a single frame may be noticed or it may not. It depends on many factors I think. But "subliminal" advertising I believe is based in some cases on such an effect.
I seem to recall, in high school, the speed of perception by any person depended on one aspcet of their IQ.
I was never very good at this and I always attributed it at my lack of ability with non-visual or experiential-less activities. I always felt cheated due to
this unknown deficiency. It was, of course, not my fault.
Additionally, there was a day when we called the movies 'the flicks.'
That is because in the early days of movie-making the film makers tried to economize in the amount of film and only showed their creations at 8-12 frames per second and under such conditions humans of the time noticed the dark interval between frames ... the screen going dark for the advance cycle and then lighting up to throw the current frame onto the projection screen.
As things improved and society became more afluent the taking and projection
rates of motion pictures were increased so that the flicker effect was
minimized. This happened around 20 or so frames per second.
BUT, the situation improved even more when someone (smart person) figured out
that film in a projector could be advanced one frame in about 1/3 the time
required for 24fps projection. So, the 360 degree rotating shutter of the
projector was broken up into three dark and three clear spaces (I guess this
would make each of them exactly 60 degrees in size) and the film was advanced
to the next frame every third dark section covered up the gate. The other two
times the film just stood there motionless. So each frame was flashed on the
screen three times and then the film was advanced to the next frame which was
flashed three times and so on. So the frequency of flashing was increased from
24 light or image flashes a second (early technology) to 72 flashes a second
(improved technology). This of course improved further the flickering nature of
motion picture projectors.
The films were still _made_at 24 fps (sound films) while amateur films were
made at 18 fps.
Well, I ran out of ideas. They are around here somewhere but can't find them. BTW, April 1 was some time ago but ...
cheerio, andy
S. Shapiro
----- Original Message ----- From: "ADavidhazy" <andpph@xxxxxxxxxxxxxxxxxx>
To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@xxxxxxxxxxxxxxxxxxxxxx>
Cc: <andpph@xxxxxxxxxxxxxxx>
Sent: Tuesday, April 12, 2005 4:25 AM
Subject: 24 fps in question
k et al, :)
I think from memory the human eye has an effective aperture range from about f5.6 to around f16, we supposedly 'see' at 24 frames per second..
A high school teacher once told me that we see at 24 fps ... I never forgot
this because he was, in my opinion at the time, just wrong.
The fact is I am not bothered much by such minutia anymore but I should like
to note that we see not in intermittent fashion as implied by "fps" but that
our vision, our perception of reality, is continuous. We can be "fooled" into
believing that a stream of images that differ slightly from each other when
presented to our eyes produces the sensation of continuous motion and
"flickerless" presentation when the frequency equals or exceeds 24 fps. But
that does not mean we see at 24 or whatever frames a second.
:)
need some coffee ...
g'day! andy
