Xref: utzoo comp.graphics:6870 rec.video:7516
Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!ucsd!nprdc!mostelle
From: mostelle@nprdc.arpa (Jim Mosteller)
Newsgroups: comp.graphics,rec.video
Subject: Re: HDTV and ATV Glossary (TN32)
Summary: Showscan, IMAX and OMNIMAX (R) frame rates
Message-ID: <3272@arctic.nprdc.arpa>
Date: 14 Aug 89 18:55:46 GMT
References: <120919@sun.Eng.Sun.COM> <121076@sun.Eng.Sun.COM> <278@bilver.UUCP> <26754@amdcad.AMD.COM>
Sender: news@nprdc.arpa
Reply-To: mostelle@nprdc.navy.mil (Jim Mosteller)
Organization: Navy Personnel R&D Center, San Diego
Lines: 20

In article <26754@amdcad.AMD.COM> phil@diablo.AMD.COM (Phil Ngai) writes:
  (text deleted)
>Does anyone know if IMAX or OMNIMAX use higher frame rates, or just
>more film? 
  (text deleted)

Both IMAX and OMNIMAX pass film at a "normal" 24 FPS, but strobe each
frame twice, giving an effective 48 images per second -- smoother,
less flicker to watch. 

As I remember it, Showscan not only passes film at 60 FPS, but also
double-strobes for an amazing 120 images per second.  At that rate,
the eye never has to try to compensate for any flicker at all --
_very_ smooth; very impressive.

Disclaimer:  It's been a few years since seeing a Showscan demo; my 
memory may be off, or not reflect their current art.

--
Jim Mosteller         mostelle@nprdc.navy.mil