[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: transferring super tv




Darren --

If we went all the way to .980 x .735 with the TV Transmitted, i.e.,
telecine scanned area, there would be no allowance at all left for
mechanical tolerances and thermal expansion/contraction, shrinkage
of the film, etc.  As a result, black unexposed edges would creep
in all the time.  Using .945 x .709 leaves thirteen thousandths top
and bottom, which should be a comfortable margin.  (It'll also hide
small amounts of dust in the camera aperture.)

The other issue is that the larger scanned area requires you to
abandon the use of many lenses that were designed for the Academy
aperture, and don't cover the larger frame with image.  That's why
we're using .832 x .624 for Super 35 shot for TV.  I'm not sure where
.900 x .676 came from, but my guess is it might be a compromise that
allows the use of some more lenses than .945 x .709

These numbers are for the full scan, not for the safe action area.
The reason for safe areas is that CRT based TV sets are cheap and
sloppy, and they rely on overscan to hide edge artifacts.  The amount
of overscan is not well controlled, but on 90% of TV sets, the plastic
around the picture tube should land somewhere between the full scan and
a frame that's nine tenths as big in both directions.  For instance,
for .900 x .676, the safe area would be .810 x .608.  Landing somewhere
between doesn't mean that it lands centered, either.  A TV set could
match the telecine extraction area on the left side, and TV safe on the
right, and still be considered OK.  The good news for the future is that
things like DLP and LCD are precise to the pixel, so this p.i.a. will go
away with CRT's.  The bad news is that such displays (plasma, too) are
now being designed to land somewhere in between, to match CRT sloppiness.

-- J.S.




---
Thanks to Manny Cervantes for support in 1999
No advertising/marketing allowed on the main TIG.  Contact rob at alegria.com
anonymous messaging now at http://www.alegria.com/HyperNews/get/ubique.html
1052 subscribers in 41 countries on Thu Jul 22 03:01:09 CDT 1999 
subscribe/unsubscribe with that Subject: to telecine-request at alegria.com
complete information on the TIG website http://www.alegria.com/tig3/