[time-nuts] Hi Power LED Light power supply...

[Tom Knox]

I remember reading that Hollywood played with faster frame rates and found a substantial number of people experience motion sickness.

Thomas Knox



> Date: Tue, 18 Sep 2012 10:51:07 -0700
> From: jimlux at earthlink.net
> To: time-nuts at febo.com
> Subject: Re: [time-nuts] Hi Power LED Light power supply...
> 
> On 9/18/12 6:54 AM, Bob Camp wrote:
> > Hi
> >
> > The shutter on a conventional movie projector is very much an on / off
> > device. They run well below 120Hz.
> 
> Actually, the typical movie projector uses a rotary shutter which runs 
> at twice the frame rate (e.g. 48 flashes/second) and is hardly a fast 
> transition.
> 
> The actual waveform is more like a trapezoid (imagine a narrow beam of 
> light going through a rotating disk with two sectors in it..)
> 
> There's also noticeable movement of the film as the shutter is opening 
> and closing, however, your eye/brain is pretty immune to overall image 
> shifts, particularly when it fills the field of view: it's not much 
> different than handling the saccades of your normal eye movements.
> 
> 24 fps is quite visible to most people (hence interlace on TVs to get 50 
> or 60 fields/second)
> 
> 
> 
> 
> 
> The phosphors in a white LED are at least
> > as long persistence as those in a TV set. There are a *lot* of TV's out
> > there that refresh at 60 Hz or less.
> >
> > Bob
> >
> > -----Original Message-----
> > From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> > Behalf Of Poul-Henning Kamp
> > Sent: Tuesday, September 18, 2012 9:05 AM
> > To: Discussion of precise time and frequency measurement
> > Subject: Re: [time-nuts] Hi Power LED Light power supply...
> >
> > In message <AC9E4C92327746D4A521FACD35D9D654 at vectron.com>, "Bob Camp"
> > writes:
> >
> >> I suspect those same 120Hz sensitive people would not be able to watch TV
> > or
> >> a movie :)....
> >
> > I suggest you either carry out a couple of experiments yourself, or
> > go a little easy on the irony.
> >
> > CRTs, and LCDs go out of their way to avoid flickering using physical
> > or electronic persistence, whereas a naked LED wil happily flash
> > up to several hundred kHz if you ask it to.
> >
> 
> 
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