[tig] RE: Tig digest, Vol 1 #1019 - 1 msg

Laurence Claydon laurence
Thu Oct 7 18:29:47 BST 2004


One of the issues of running older material with red light (notably reverse scan) is that thesedays the HF equalisation is set using pink noise on colour stock. This therefore compensates for both the HF rolloff of the reader AND the stock AND the recording process. This is fine with a new track in Dolby SR on new stock. Get a slightly worn early A-Type and crackle and hiss encroach! (I once discovered this doing a service visit for a 'Star Trek' day a few years back with prints ranging from 1979 A-type through to Dolby Digital). This is compounded with density tracks.

Dolby used to provide (combined with tone on the other side- CAT 69) pink noise on black and white stock which was recorded at half speed. This provides EQ only for the replay chain due to its HF content which is flatter to higher frequencies than normally recorded. The difference between the two is less noticeable on white light readers which have a wider slit and therefore only flat to about 12kHz after Eq. The Reverse Scan red LED units can be Eq's flat to 14-16kHz, with more 5-6dB more HF compensation being seen when aligning with CAT 69P. Hence the noise on older material!

Try lining up with older CAT 69 and let the HF content of the source material roll-off as nature intended. For older mono material, make sure you use a decent 8kHz rolloff Academy filter at some stage in the process (although this can be applied after the initial transfer)

Hope this helps!

Laurence Claydon
Bell Theatre Services Ltd
London, UK

Today's Topics:

   1. Re: FW: Tig digest - red LEDs (Mikko Kuutti)


Message: 1
From: Mikko Kuutti <mikko.kuutti at sea.fi>
Subject: Re: [tig] FW: Tig digest - red LEDs
Date: Wed, 6 Oct 2004 14:52:53 +0300
To: Telecine Internet Group <tig at colorist.org>

Hi folks,

a slight warning from the world of film archives. We are investigating 
the different possibilities of equipping our projectors with red light 
readers, but have been warned by many fellow archives that there are 
real world problems with reading silver sound tracks with red light - 
despite their advertized omnipotence.

The norm in cinematheques now seems to keep the old lamphouse and to 
add a new red light reader. We must be able to properly read everything 
from nitrate prints with intensity sound to the new cyan prints as they 
start to appear.

Best regards,


-- Mikko Kuutti
-- Deputy Director
-- Suomen elokuva-arkisto / Finnish Film Archive
-- P.O. Box 177, FIN-00151 Helsinki, Finland
-- Pursimiehenkatu 29-31 A, 00150 Helsinki, Finland
-- tel. +358 9 6154 0254, fax +358 9 6154 0242, mobile +358 40 900 0455
-- mikko.kuutti at sea.fi

On 4.10.2004, at 23:13, Schnuelle, Dave wrote:
> Gentlemen,
> Clint Koch at USL, one of the makers of red LEDs for film projectors, 
> is
> interested in your problem.  His approach is to replace the quartz lamp
> with a red LED illuminator, as he has done for film projectors.  There
> is no reason this should not work, as Dave suggests below.  In our
> experience, a red LED with a cyan dye track gives the same levels as
> white light with silver sound tracks.  The issue is the mechanical 
> mount
> to ensure the LED light is focused on the film sound track.  I've given
> him your names as possible contacts who may be able to recommend 
> someone
> to work with at Thomson and Cintel to get red lamps for the telecines.
> Sam Chavez is another good prospect, as Craig suggests.  I'd contact 
> him
> also to see if he wants to work on this.
> Best regards,
> Dave
> Dave Schnuelle
> Director, Image Technology
> Dolby Laboratories, Inc.
> 3601 West Alameda Ave.
> Burbank, CA  91505
> Tel:  (818) 823-2800
> Fax: (818) 557-0890
> Email:  dls at dolby.com


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