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From: chrisl@cbmvax.cbm.commodore.com (Christian Ludwig - CATS)
Message-Id: <9110252002.AA13682@cbmvax.cbm.commodore.com>
Subject: Re: why 30hz flickers and movies don't
To: dstamp@watserv1.uwaterloo.ca (Dave Stampe-Psy+Eng)
Date: Fri, 25 Oct 91 16:02:43 EDT
Cc: glove-list@karazm.math.uh.edu
In-Reply-To: <9110251847.AA19649@watserv1.uwaterloo.ca>; from "Dave Stampe-Psy+Eng" at Oct 25, 91 2:47 pm
X-Mailer: ELM [version 2.2 PL0]
> >Been following the thread on Sega LCD glasses.
> >
> >Why does 30hz to each eye cause a flicker, when 24hz (Film) does not?
> >
> 
> I believe the reason is that the Sega glsses give you 50% duty cycle
> on the images to each eye, and a movie projector gives over 90%.
> This results in 5 times the 24 Hz/30Hz flicker (at least).  You can
> see the flicker in movies if you have a fast-moving white object on
> a dark background-- just look at the edges.
> 

Also...  movies are filmed at 24fps, but when projected, each frame is shown
TWICE in that 1/24sec bit of time.  This approximates the effect of 48fps,
hence, no (or at least far less) flicker.

Chris Ludwig