Re: Another tech question

From: Joost Rekveld (email suppressed)
Date: Sat Mar 25 2006 - 12:23:10 PST

what I tell students is that there are two phenomena:

- the phi phenomenon: the effect that if you show a dot in position
'a', followed by a dot in position 'b', people will see this as one
ball moving from 'a' to 'b', not as two balls appearing and
dissapearing. You could see this as a kind of gestalt phenomenon; our
mind picks the most down-to-earth interpretation to make sense of the
dots shown.

- the phenomenon that used to be called 'persistence of vision': the
idea that light somehow lingers in the eye and that we see rapid
flashes as continuous light. I've once read that 'persistence of
vision' is actually not a proper term: the point is that our visual
system is too slow to detect changes faster than a certain limit speed,
it is not some kind of 'trace' lingering on, not some kind of memory.
I'm still not sure whether that is academic hairsplitting or the most
profound thing i've ever read...

illusion of continuous motion where in fact only discontinous
motion/change exists is entirely due to the phi phenomenon, seeing
immutable existence where there is in fact a rapid succession of dark
and light universes is related to the 'persistence of vision'.
Having a shutter was a technical necessity in the time of a material
film strip, to not spoil the magic of moving its mass through an
aperture. There are many moving image media without
shutter/stroboscopy, as the prism transports mentioned, as video
phosphorous screens, as lcd screens/projectors, but also thaumatropes
(discs flipping quickly to merge the front and back drawing) and flip

hope this helps,


On 24 Mar 2006, at 22:59, Jonathan Walley wrote:

> I've just read an essay that offers yet another ontology of cinema,
> and I believe that it is flawed. The author stipulates that
> stroboscopy is an essential characteristic of cinema, partly on the
> basis that "all movies" (his words) to date have involved stroboscopy,
> because the flicker is necessary for the illusion of motion and/or
> change on screen.


                         Joost Rekveld


"The mystery of the world is the visible, not the invisible"
(Oscar Wilde)


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