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Re: Telecine No- Drift !
- To: Telecine User Group <telecine at sun.alegria.com>, Peter Swinson <106005.677 at compuserve.com>
- Subject: Re: Telecine No- Drift !
- From: "Robert Lovejoy" <rlovejoy at bellatlantic.net>
- Date: Wed, 16 Jul 1997 09:07:14 +0000
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Mr. Swinson comments:
> Robert implies that telecines are not stable in terms of their
> representation of transferring film image densities to video levels.
> However modern CRT based digital telecines have built in absolute
> references and drift correction. The earliest version of this was Ursa's
> automatic alignment.
This is indeed good news! Does this mean if a client does a transfer
at facility A he can copy the list to a floppy and take it to
facility B which has the same models of telecine and color correction
devices, and it will look the same? That, to me, would be absolute.
I doubt we have that yet, perhaps in a few years...
> I can assure you
> light bulbs age a lot faster and over a much greater brightness range than
Over 2000 hours on my light bulb and still zero changes. The
compensation circuitry certainly does its job!
> Modern telecines, both CRT & CCD based utilise digital color channels, no
> drift here.
Front ends are still analog.
> Bear in mind that CCDs are analog detectors that do drift quite
> considerably, so while the latest CCD telecines have feedback to help avoid
> the relatively large variations in their light sources, what is done second
> to second or even hour to hour to remove CCD drift ? Maybe something or
> maybe not.
PECs are also analog devices and I've seen them become unstable at
high gain settings (of course this was on an older machine)... As
far as CCD drift, it's a non-issue so I'd hazard a guess something
was being done.
Anyway, I'm glad that telecines in general are more stable now than
they were ten years ago. I wonder if an absolute standard will be
achievable or necessary. The important thing is that in newer
telecines, clients have a better chance of recovering their
corrections than they do with older telecines. As far as the battle
goes between manufacturers and imaging devices, I'm sure there are
strong points and weaker points in each system. I'm glad that there
is variety in the world, that we as facilities have options like
these available to us. It was not my intention to beget a war over
which system is more stable, but to bring my own (limited) experience
to bear to answer a question posed to the list. Peter's reply has
informed me of the increased stability of newer CRT machines, yet I
think we all have a way to go before we have any absolutes in the
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