[Tig] Tig Digest, Vol 94, Issue 1

Terry Lockhart terry at finishedit.com
Mon Aug 25 19:24:30 BST 2008


Granted, all these issues introduced by the various layers of  
synchronization have their effect, but do not forget that probably  
most significant of all, sprocket driven devices are notoriously  
prone to flutter simply due to the mechanical effects of sprocket  
teeth ticking in and out of holes in the media. Even when free- 
running (not locked to anything). Also the holes themeslves have an  
effect, which is why customarily rollers, guides, heads, sound drums 
(flywheels) have cut-out areas machined under where the sprocket  
holes travel.

-- 
Terry Lockhart
Chief Engineer/IT manager
Finish Editorial
162 Columbus Ave.
Boston, Ma 02116-5222

direct/vm 617 850 6133
main  617 292 0082 or 850 6100
fax   617 292 0083
cel 617 775 3195
<terry at finishedit.com>
<www.finishedit.com>

"What this country needs are more unemployed politicians."
-- Edward Langley



On Aug 25, 2008, at 1:28 PM, tig-request at tig.colorist.org wrote:
> ------------------------------
>
> Message: 11
> Date: Mon, 25 Aug 2008 00:12:52 -0400
> From: Wilf Giovanella <wgiovanella at rogers.com>
> Subject: Re: [Tig] wow + flutter
> To: Graham Collett <grahamcollett at sprockets-telecine.co.uk>
> Cc: 'Group Internet Telecine' <tig at colorist.org>
> Message-ID: <48B23144.3030808 at rogers.com>
> Content-Type: text/plain; charset=us-ascii; format=flowed
>
> Graham Collett wrote:
>
>> 1980 subscribers as of August 2008
>> Sohonet ( http://sohonet.co.uk ) supports the TIG
>> Eric Maurer supports the TIG
>> http://www.colorist.org/wiki3
>>  ====
>>
>>
>> For the same reason that a film can run on a telecine and still be
>> unstable ... Multiplied by 2 for the same problems on the sound  
>> follower
>> ..and then combined with synchronsining slackness/errors and hey  
>> presto.
>> I believe the Magnotech has the tightest sync .. Cintel ferrit even
>> though was very good down to a 1/4 frame sync was only driven by 1ppf
>> ...
>>
>> Graham Collett
>> Sprockets(telecine) Ltd
>> www.sprockets-telecine.co.uk
>>
>>
>>
>> -----Original Message-----
>> From: tig-bounces at tig.colorist.org [mailto:tig- 
>> bounces at tig.colorist.org]
>> On Behalf Of Rob Lingelbach
>> Sent: 24 August 2008 20:04
>> To: Group Internet Telecine
>> Subject: [Tig] wow + flutter
>>
>>
>> 1980 subscribers as of August 2008
>> Sohonet ( http://sohonet.co.uk ) supports the TIG
>> Eric Maurer supports the TIG
>> http://www.colorist.org/forums
>>  ====
>>
>>
>> I've always wondered, if a mag track is locked to a telecine, and the
>> reference is regular, how can audio (noticeable particularly on piano
>> tracks) flutter?
>>
>> Once long ago I think it was Dave Tosh who told me there really is no
>> complete guarantee that the speed is constant.
>>
>> --
>> Rob Lingelbach
>> rob at colorist.org    http://www.colorist.org/robhome.html
>>
>>
>>
>>
>> _______________________________________________
>> http://www.colorist.org/wiki3
>>
>>
>> _______________________________________________
>> http://www.colorist.org/wiki3
>>
>>
> I have found that if the telecine is generating biphase with a  
> sprocket
> drive, then anything in the film path after the capstan can affect the
> mag follower, this includes PTRs.
> If the capstan servo is generating the biphase for the follower, then
> the flutter is a factor of the follower's servo and how tight it is
> locked to the biphase.
> I have seen this on all followers, that are driven by biphase, mag,  
> 1/4"
> and hard disk systems.
> If the telecine uses scan tracking or any such patch shifting to  
> reduce
> burn, then the film is slowly shifting phase, following the patch.   
> You
> can confirm this by comparing the timecode on follower when locked to
> the telecine, with video frame sync.  The sync word will shift as the
> scan track shifts.  Depending where the sync word is relative to the
> video frame, you may see a timecode error.
> Have you ever wondered why sometimes audio durations are off by 1  
> frame?
>
> Wilf Giovanella
> Deluxe Postproduction
> Toronto
>
>




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