Hi all, Just following up on the original thread for anyone interested in such things.
The Kodak Super-40 Shutter that Pageants come equipped with, as Dominic and Scott suggested, is a variable shutter; that is, it is two-bladed at sound speed (24 fps) and three-bladed at "silent speed." The clever mechanism that makes this possible uses spring tension to keep it in the three blade position, unless the greater centrifugal force of the shutter rotating at sound speed causes the shutter to overcome the spring tension and move into the two-bladed position, *unless* the projector is started in sound speed and then switched to silent, in which case the shutter cannot return to the three bladed position. The trick is, what is "silent speed?" The "standard" for silent speed on 16mm projectors changed during the 1960s (after the introduction of Super8 in 1965?) to 18 fps, while earlier Kodak Pageant models, such as the AV-126-TR, ran at 16fps for silent speed. So, later model Kodak Pageants, such as the 250s runs at 18 fps for silent speed, while the AV-126-TR runs at 16fps for silent speed, which is why the AV-126-TR would have a more noticeable flicker (if I recall correctly, anything below 50 flashes of light per second is perceptible). 16 fps x 3 = 48 flashes of light per second 18 fps x 3 = 54 flashes of light per second 16fps x 2 = 32 flashes of light per second 18fps x 2 = 36 flashes of light per second Madison Los Angeles On Sun, Feb 24, 2019 at 9:36 AM Madison Brookshire <[email protected]> wrote: > Thank you, Dominic and Scott! > > Scott, may I ask if there is a specific inverter you recommend? They seem > to very greatly in terms of cost with more than few costing more than the > projector itself. > > All the best, > Madison > > On Tue, Jan 29, 2019 at 10:46 AM Scott Dorsey <[email protected]> wrote: > >> I think he means that when you go from sound speed to silent speed, the >> shutter angle changes in order to reduce flicker at the lower speed, by >> means of a little metal clip on each shutter blade that is moved in and >> out by centrifugal force, and that on many of the Pageants that clip >> sticks >> and so it takes a second or so for it to move. And during that second or >> so there is noticeable flicker. >> >> If you run a 60 Hz Pageant at 50 Hz, it will behave differently because >> the >> motor will be running 20% slower. It will probably take less time for the >> clip to move. Pageants designed for 50 Hz will run at the same speeds and >> probably behave similarly, but I have never seen one and can't say for >> sure. >> >> I would suggest if the original poster wants the exact effect that they >> bring their own projector and run it on a a 60 Hz inverter abroad. >> --scott >> >> _______________________________________________ >> FrameWorks mailing list >> [email protected] >> https://mailman-mail5.webfaction.com/listinfo/frameworks >> >
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