Who writes these standards, anyway, and why don't they document
these things better? What do they get paid for? :)

The real question is what do you have to smoke to devise standards whether
the ratio of pixels in the horizontal and vertical directions is neither
4:3
nor 16:9? Does it not make eminent sense to have the same resolution
(pixels/mm) in both directions at least for *one* of 4:3 and 16:9?


I think it already is the same resolution in both directions if you take
into account the Kell factor due to interlace.
The effective number of active lines in 625 analogue is more than a field
(287½) but less than a frame (575), because fine detail at the full 575 line
resolution flickers violently as it is only refreshed at 25 Hz. The
effective vertical resolution is 575 lines times the Kell factor, which is
usually taken as about 0.7, making it almost exactly 400 lines. Multiply
this by 4/3 and you need 533 pixels horizontally, that is 267 cycles in 52
microseconds, which works out at 5.1 MHz. This was how the vision bandwidth
for the original 625 line monochrome System B was arrived at. (It was
rounded down to 5 MHz.) Taking the Kell factor into account, the pixels are
squa 400 x 533. The only trouble is that these square pixels do not exist
in any still picture, field or frame. The pixels are virtually square when
you take an average between field resolution and frame resolution, as the
eye does when watching an interlaced TV picture.

In article , Mat
Overton writes
It's so long since I've seen a non-Imax 70mm print in the cinema, I've
no idea if they've successfully adopted an optical audio format for 70mm
or not, digital or otherwise.

Apart from DTS timecode no. Although Dolby did patent it's sprocket hole
spaces, but then they did the same for the opposite side of 35mm film, but
that was just to protect their interests.
Mind you who needs it - When you've seen a brand new mag striped print of
2001 on the Cinerama screen in Bradford you wonder what they'd bother with
anything else. (Apart from the envoronmental issues of mag striping, the
wearing out of the track, the degrading over time, the-...... etc, etc.!)

I agree that it's stunning.

It's a shame though that the vast majority of film production is on
35mm. printed up to 70. You don't get the full benefit.

IIRC, making a 70mm print is a 3-stage process: Make the optical print,
stripe it, record the sound. In consequence, 35mm showprint = around
100UKP, 70mm showprint = 10,000UKP.

That and (as you mention), the fact that they wear out much faster than
comopt (of whatever sort), are why you never see 70mm in the cinema
normally over here - it's just uneconomic to fly prints across the
Atlantic.


Regards,

Simonm.

--
simonm|at|muircom|dot|demon|.|c|oh|dot|u|kay
SIMON MUIR, UK INDEPENDENCE PARTY, BRISTOL www.ukip.org
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It's a shame though that the vast majority of film production is on
35mm. printed up to 70. You don't get the full benefit.

IIRC, making a 70mm print is a 3-stage process: Make the optical print,
stripe it, record the sound. In consequence, 35mm showprint = around
100UKP, 70mm showprint = 10,000UKP.

That and (as you mention), the fact that they wear out much faster than
comopt (of whatever sort), are why you never see 70mm in the cinema
normally over here - it's just uneconomic to fly prints across the
Atlantic.


ISTR there is now only one European company who can print mag striping due
to the serious environmental issues involved (waste chemicals etc). Of
course America doesn't give a damn about that and many labs over there will
happily print 70mm mags when they are (rarely) needed. Some 70mm prints
where made are now DTS only. It's also fortunate that the extra sprocket
hole per frame means that the timecode is much larger, and therefore much
more reliable than the (still very reliable) 35mm version. Unless Dolby used
the opposite side as a 100% back up track, I couldn't see DD ever appearing
on a 70mm print.

Without wanting to get too off topic. There has been the recent change to
remove silver from optical print soundtracks, which makes film printing more
environmentally friendly, however I bet that was more to do with the price
of silver and the cost of the chemicals.....

http://palimpsest.stanford.edu/byfor.../msg00050.html