P3D keystoning

[Richard Twichell <rmt@xxxxxxxxxxxxxxx>]

Tony Alderson writes:

>IMHO, this practice is common in stereo cinematography for economic
>reasons. It is easier to adapt existing monoscopic equipment by using
>toe-in than to build stereo movie cameras.

Wouldn't the keystoning inherent in toeing in the cameras be cancelled 
to some extent by the keystoning produced in the projection booths?  
50's 2-strip 3-d films were projected by adapting the existing 2-machine 
rigs (larger magazines; selsyn or mechanical synchronization).  These 
machines were by necessity toed in as they had to be located at least 5 
or 6 feet apart to allow them to be worked on and operated. Larger 
theatres tended to have more separation between machines, just because 
there was more room available.  It would be interesting if someone with 
access to technical literature (SMPTE?) could check and see if there was 
a convention concerning projecting the "right" image from the "left" 
machine, and vice-versa.

Dick Twichell


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