From: amanda christie (email suppressed)
Date: Thu Jul 31 2008 - 23:03:26 PDT
something to consider when choosing a projection speed is flicker.
you're right in saying that at 18fps the image will be on the screen longer... but the flicker will also be more visible... because the screen will be black longer.
24fps was accepted as a standard frame rate when sound was introduced because that was how sound sounded best at that time....
but later on, as technology advanced, it was realized that for the eyes and the brain... something like 60fps was best (someone can correct me with the exact number if they know it... it's 2:30 am here, and i have no reference books handy)..... so basically... at anything slower than 60 fps, the human mind tends to drift and wander in between frames, and therefore we are more easily distracted... ( our minds are speedy little things)
so to compensate for this, projectors have multiple blades... so for instance, in a two blade projector, each image is projected twice, as the two blades rotate one cycle per frame... this creates a flicker of 48fps... better than 24fps, but still less than 60fps, so the mind still wanders....but not as much....
enter cinemascope.... apparently, the human eye can take in 1:85 in peripheral vision... but the human mind wanders between the frames at the 48fps of a double blade projector (which projects 24 images, 2 times per second)... so they came up with the super wide screen of greater than 2:1 ratio (there were various ratios used as the formats progressed) because it covers more than peripheral vision can cover... therefore... when your mind wanders between frames, it wanders and explores the rest of the projected image that it cannot take in during the peripheral glance.
at least that's what i've been told... or that's what i've understood when i've been told.
someone please correct me if i'm wrong.
if i were you... i would create for 24fps... and if you're up for it... make or modify your own projector to suit your desired needs and effects, by playing with belt placement and shutter design.
with a pounding headache,
amanda dawn christie
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