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P3D Re: IMAX 3D projection
Tony Alderson <aifxtony@xxxxxxxxxxxxx> wrote:
> Andrew Woods wrote:
> >IMAX projectors are fitted with an alignment adjuster which can be
> >dynamically controlled by a computer. It is probably this system which was
> >malfunctioning in the Arizona system. The system allows alignment errors
> >(which may occur during filming, printing, etc) to be trimmed out at the
> >projector end during the screening. <
>
> Wow! Really? I guess it ISN'T "obviously impractical to adjust the
> alignment shot-to-shot during projection of the movie."
>
> I have considered the possibility, but decided the engineering wouldn't be
> worth the trouble. I stand corrected on that, anyway. How much time lag is
> there for the corrections? Can the system keep up with quick cuts? I think
> I'll have to dig out my stuff on IMAX and recheck things.
I was told this by the Manager of Film Technology at IMAX several years ago.
I guess there have been many changes to the design of their projectors
since then, but with the enormity of the IMAX screen I don't think
you'd be able to do without it.
I don't know how fast it operates.
Tony Alderson <aifxtony@xxxxxxxxxxxxx> also wrote:
> Boris Starosta (digest 2758) Reviewed: Into the Deep
> >I did not perceive any flicker at first, though later I saw a little
> >"jumpiness" in bright objects moving rapidly across screen.<
>
> I suspect this was strobing from the frame rate, not stereo ghosting. You
> can see this artifact in horizontally (rapidly) moving objects in most
> movies.
Agreed.
> You need to get up to Showscan frame rates to eliminate this.
Or IMAX HD which runs at true 48 frames per second unlike standard
IMAX which is 24 frames per second double shuttered.
Andrew Woods. http://info.curtin.edu.au/~iwoodsa
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