From: Jonathan Walley (email suppressed)
Date: Tue Oct 30 2007 - 15:04:03 PDT
That's an excellent essay that I've recommended to many students and
colleagues. I also endore:
Both essays demonstrate - pretty convincingly, I think - that
persistence of vision cannot account for the appearance of continuous
light in film.
It's important not to conflate two illusions: the illusion of a
consistent light source when it is in fact flickering (I understand
this illusion to be called "critical flicker fusion"), and the illusion
of movement on the screen, which I refer to as "apparent motion" when I
teach it - I've heard people call it the "phi phenomenon," but this
names a different kind of illusory motion perception than the one
produced by tiny increments of change in "normal" cinema, which
produces the illusion, for instance, of someone walking from one end of
the frame to another.
(Embarrassingly, I just published an essay in which I used the term
"phi phenomenon" when I really meant simply "apparent motion," which
might also be called "partial movement" - this is described in the
essay Todd cited).
Granville, Ohio 43023
On Oct 30, 2007, at 4:59 PM, Todd Eacrett wrote:
> The myth of persistence of vision was first debunked 30 years ago:
> Todd Eacrett
> ----- Original Message -----
> From: Flick Harrison <email suppressed>
> Date: Tuesday, October 30, 2007 1:28 pm
> Subject: Re: how much of what we see is black?
>> Hate to be a splitter.
>> We don't actually "see" any blackness at all. From our point of
>> view, there is no blackness.
>> Aside from the witty comment on here that you can't see
>> is the absence of an image, so it's more like not-seeing).
>> Persistence of Vision is the phenomena wherein your optic nerve
>> whatever) takes time to "reset" i.e. cool down and stop
>> the last image you saw.
>> Frame rates which create the optical illusion of continuous
>> are using this phenomena.
>> The image stays in your optic nerve while the shutter closes,
>> advances the frame, then re-opens just in time for your optic
>> to absorb a new image.
>> Your eye / mind never notices the blackness because it's not fast
>> enough to see it.
>> I.o.w., your eye is fooled into thinking there is no darkness. The
>> darkness is too short for you eye's mechanism to register.
>> It;s not like the optical illusion of a bunch of dots becoming a
>> straight line as you pull back. That is simply perceptual / mental
>> illusion, at least until you get back so far that the dots fall
>> the resolution of your eyeballs.
>> It's more like an optical override.
>> To be clear - continuous motion on screen is an optical illusion,
>> created by a series of still pictures. Continuous brightness on
>> screen is a neurological illusion, not an optical one - though
>> splitting optic nerve-hairs.
>> * FLICK's WEBSITE:
>> * FACEBOOK
>> * BLOG / NEWS:
>> * MYSPACE:
>> On 30-Oct-07, at 6:53 AM, Yoel Meranda wrote:
>>> A question I'm curious about...
>>> When a film projector is running, what is the percentage of
> time the
>>> light is interrupted by the shutter? In other words, what
>>> of what we see is darkness?
>>> I realize that this question will have different answers for each
>>> I am mostly curious about 35mm projectors but any clue on
> any other
>>> projector would be great. Even guesses would be fine if no one
>>> concrete answers.
>>> For info on FrameWorks, contact Pip Chodorov at
> <email suppressed>.
>> For info on FrameWorks, contact Pip Chodorov at
> <email suppressed>.
> For info on FrameWorks, contact Pip Chodorov at <email suppressed>.
For info on FrameWorks, contact Pip Chodorov at <email suppressed>.