Re: NuOptix Pulfrich

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

Gregory J. Wageman writes

>This isn't quite accurate.  Increasing the frame rate of motion picture
>film doesn't necessarily result in less *motion blur*.  While the frame
>rate necessarily limits the *maximum* exposure time (since the film
>is moving it can only be in the gate for so long), even at three times
>the normal 24FPS frame rate, you can still get about 1/80th second
>exposure, which as we know from our still work isn't a particularly
>"fast" shutter speed.  Depending on your degree of pickiness, speeds
>of 1/500th or above are necessary for *really* sharp work if the camera
>is hand-held; you can get away with less if a sturdy tripod is used.

You mention that you can still get about 1/80 second exposure which is
still pretty slow to capture hi speed but nonetheless...Given all things
are equal, going 3 times, from 24fps to 72fps does decrease the exposure
time from 1/24th of a second to 1/72 of a second. Yes it's true it still
doesn't exactly freeze the motion for "still" camera work but does make for
sharper "moving" picture film work. In any case the NuOptix Pulfrich movie
was done at 5 times the normal frame rate.
Another point is that at 1/500th would kind of be impractical since the
FOD would be reduced and since the pulfrich effect relies on the background
and foreground to great extent this wouldn't help. Also since the scenes
and objects are in constant motion it's not necessary to actually "freeze"
the motion but rather the intent is to reduce the blurriness of the 
captured motion somewhat. To actually freeze the motion even higher frame
rates would be required. Plus for motion picture "freezing" it still
requires hi frame rates even if high speed shutters are used because for
example if a slow frame rate was used with a fast shutter speed what you
would get if you were trying to capture a bullet ((Just got an idea. Wasn't
that famous shot of a bullet thru a card also captured as a moving picture.
If yes as I remember then with our special ;-) pulfrich glasses it might be
able to be viewed in 3d. Of course only 2 planes of depth would be
discernable in this case if it works.)) would be a frozen shot as the 
bullet was coming out of the barrel and then maybe of it after it passed the
playing card. This wouldn't really be motion picture freezing. At the hi
frame rate you would see a smoother transition of the bullet going thru
the air. Finally as Marvin Jones mentions, strictly speaking the
shutter speed is faster than quoted because the shutter blades cover the
film as it advances to the next frame which means at 24 fps a portion of
the total 1/24 sec time is used for advancing the film.

Gabriel  


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