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RE: Pin Registration (was Re: Kepping)

On Mon, 10 Mar 1997 13:55:56, Christopher Bacon wrote
>The dimensional stability of film, when subject to humidity changes, is
>actually quite poor.  Consequently, it is altogether improbable that any pin
>registration system would ever duplicate exactly what took place in a camera
>once a piece of film has been processed, since film inevitably comes out of
>processing a different size and "stiffness" than when it went in.  In fact,
>unless the telecine and its pin-reg gate live in an environment where
>temerature and humidity are very accurately controlled, and the film is given
>ample time to acclimate to that environment, it would be most unlikely that
>you could pin-reg the same frames on the same machine (without changing
>anything) an hour later and come up with the same pixels both times.

Unless the dimension of the perf hole itself changes, the photographed image
relative to the perf hole dimension will remain intact.  The pin/perf
interface is the dimemsional reference, isn't it?  I will not argue against
the fact that film dimension changes upon processing and subsequent handling.  

The more I've thought about this whole real vs. non real registration thing,
the more I'm inclined to believe that, (for one), the MetaSpeed/RTS system
is extremely repeatable and stabile based on tests done here at FWC.  But
I've also done tests elsewhere where the SteadiFilm (for one) did the job
better, that is, creating a difference matte from several random passes of
the exact same film frames rendered a perfectly registered (null) image.  I
also have to say that these tests on the ADAM II where highly controlled.
That is, the film was freshly shot, subject to ultrasonic cleaning and
allowed to stabilize overnight in the same room as the scanner.  The test
was performed once (10 passes) then repeated, (another 10 passes).