Leo Enticknap's eloquent essay on flicker reminded me of the problem of 50 Hertz v. 60 Hertz and some unanswered questions. I first became aware of the significance of the incompatibility thirty years ago when I was showing a Ken Loach film at the New School in New York. The film really dragged during the first screening. Then we realized it was a made-for-TV film shot at 25 fps instead of 24 fps. The 4 percent difference was not noticeable in terms of the action or dialogue but it really destroyed the rhythms. When we projected at 25 fps the film came alive again. The difference was striking, most significantly because you couldn't perceive that the film was being projected at the wrong speed at 24 fps. (It wasn't like the rushed motions we are all familiar with when silent 16 fps is projected at 24 fps.) Musicians would understand this phenomenon. In that pre-digital age, as I understood it, the practice in the UK (at least) was to do a frame-for-frame transfer of 24 fps cinema to 25 fps PAL for TV. To my mind, based on the Loach experiment, this would have seriously altered the experience. I have very little personal experience with non-NTSC TV. First, because when I'm outside the US about the last thing I want to do is watch TV. But also because for me PAL was painful to watch: it flickered! And the increased resolution only seemed to emphasize the flicker. Curiously, I don't have the same reaction to SECAM in France even though that also runs at 50 Hertz. So here are my questions: 1. Is it really possible that frame-for-frame transfers of 24 fps were the norm in 50 Hertz countries at one time? 2. Has anyone written about the psychological or social effects of this practice? How does it relate to ADHD, for example? 3. When did the practice stop? 4. Do PAL cathode ray tubes still flicker? Or has the refresh rate been increased? 5. Is there a technical difference between PAL and SECAM that reduces the perception of flicker at 50 Hz? There's an old anecdote about Ingmar Bergman suffering pangs of guilt because his audiences were watching a blank screen most of the time. He should have concentrated on video. I'll buy your book, Leo! One more thought: As Leo points out, 24 fps (doubled by the shutter to 48 fps) is the least you can get away with--and we've been stuck with it for 75 years. (Showscan never took off, although IMAX HD might still.) I think this is the mosty salient example of what we might call the Lincoln Rule of Perception: you only have to fool most of the people most of the time. A more recent example is CD audio standards (significantly inferior to the vinyl it replaced). There has been a lot of interesting work done in perceptual psychology in the last 20 years, but it seems most of it has been devoted to extending the Lincoln Rule. =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- James Monaco Harbor Electronic Publishing 80 East 11th St New York NY 10003 212 777 5463 sales: 800 269 6422 http://HEPDigital.com ---- Screen-L is sponsored by the Telecommunication & Film Dept., the University of Alabama: http://www.tcf.ua.edu