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Cyhist Feb 15 1997 B
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Date: Sat, 15 Feb 1997 20:11:30 -0800
Reply-To: les@cs.stanford.edu
Sender: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> From: Les Earnest <les@STEAM.STANFORD.EDU>
Subject: CM> Rapid arm movements
X-cc: keith reid-green <kreid-green@ETS.ORG>
In-Reply-To: keith reid-green's message of Fri, 14 Feb 1997 08:18:16 EST
<199702141614.IAA13411@Steam.Stanford.EDU>
______________________________________________________________________
Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
Keith S. Reid-Green writes:
[. . .]
But I digress. Regarding Chris's arm-waving, when we got the TV I noticed that if I moved my hand quickly in front of the set I could detect the screen blanking. This was because I would see two or three silhouettes of my hand. My brother and I had contests to see who could move a yardstick the fastest, as measured by the number of yardsticks we could count as the real one passed across the screen. For the record, each instance represented 1/30 second.
More likely each silhouette represented a 1/60 second interval -- the time between successive fields on NTSC television. Remember that two fields are interlaced to make a 1/30 second frame, but the flicker rate on any given part of the picture is 1/60 second.
-Les Earnest
______________________________________________________________________
Reply-To: les@cs.stanford.edu
Sender: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> From: Les Earnest <les@STEAM.STANFORD.EDU>
Subject: CM> Rapid arm movements
X-cc: keith reid-green <kreid-green@ETS.ORG>
In-Reply-To: keith reid-green's message of Fri, 14 Feb 1997 08:18:16 EST
<199702141614.IAA13411@Steam.Stanford.EDU>
______________________________________________________________________
Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
Keith S. Reid-Green writes:
[. . .]
But I digress. Regarding Chris's arm-waving, when we got the TV I noticed that if I moved my hand quickly in front of the set I could detect the screen blanking. This was because I would see two or three silhouettes of my hand. My brother and I had contests to see who could move a yardstick the fastest, as measured by the number of yardsticks we could count as the real one passed across the screen. For the record, each instance represented 1/30 second.
More likely each silhouette represented a 1/60 second interval -- the time between successive fields on NTSC television. Remember that two fields are interlaced to make a 1/30 second frame, but the flicker rate on any given part of the picture is 1/60 second.
-Les Earnest
______________________________________________________________________
