Re: Projector Adjustments

[P3D John Bercovitz <bercov@xxxxxxxxxx>]

I tried to look up the difference between 5-P and 7-P infinity
separations but so far I haven't had complete success.  Ferwerda 
says the infinity separation for 5-P is 63.4 (and suggests a 
tolerance of +/- 0.3).  I can't find where Ferwerda says anything 
about a standard for 7-P other than to say ISU has one.  My Reel 
3D mounting guide for 5-P has a separation of 63.6 and my Reel 3D 
mounting guide for 7-P has a separation of 63.3.  ISO 515 says the 
mask aperture separation for 5-P is 62.2 and ANSI PH3.11 says the 
mask aperture separation for 5-P is 61.9 +/- 0.1.  IMHO, the latter 
specification would be better in general because then you can have 
more depth in your scene (1.5 vs 1.2 mm) and still maintain 
standard infinity separation for projection.  On the other hand, 
the 62.2 spec is better if you have some real wimps in the 
audience who can't hack the depth.  I personally haven't found 
anyone quite that wimpy; the discovery of such a person may argue 
for eugenics.  8-)  That's pretty cavalier of me I realize; I 
should caution you that conventional wisdom says 1.2 mm is the 
maximum allowable if you want to make sure everyuone can view the 
result.  Measuring a few masks I have laying around, the RBT 
measures 61.9, the Spicer measures 62.0 and the Albion measures 
62.2.  This is for both 5 and 7 perf masks from each maker.
 
John B


------------------------------