[Tig] manual framing

Laurence laurence
Tue Mar 25 09:42:11 GMT 2003


Message: 2

From: "Jean-Clement Soret" <jean-c at moving-picture.com>

To: "Marc Wielage" <mfw at musictrax.com>,

      "TIG" <tig at snowball.calarts.edu>

Subject: RE: [Tig] manual framing

 

Date: Mon, 24 Mar 2003 16:02:50 -0000At worst, you could splice in a
foot or two of a sizing chart onto the head of every roll.  That way,
you'd know exactly where you were, North-South. The DaVinci 2K displays
this as a Hex value, but alas, it's not available in any percentage
numbers that I know of.  I gots no idea how it's displayed in
Pogle-land, having only used Pogle Platinum for data correction.

 

Hi, that would be a bit time consuming for my taste. I can deal with
differences due to machines, stock etc but what I can't accept is not to
have the possibility to store the value in your grading list. At least
Davinci gives you a value, Pogle and data Xfer engines gives you
nothing. Regards JC

 

Unfortunately, the physical means of changing framing by advancing or
retarding the film whilst in transit through the gate means that it
could not be applied as a dynamic effect whilst playing out a grading
list, without image distortion, and hence, I suspect the reason for it
being an arbitrary uncalibrated adjustment. (Having said this, anyone
who has used 'DCP blanking' on a Pogle Platinum with Pixi will know that
the figure which appears on the screen does not translate and can
represent two or three video lines within one integer value. And it can
change within these limits when saving/recalling a grading list.)

 

Historically, the Rank Mk3 framing could not be assigned a repeatable
value as the system exhibited a degree of hysteresis. The best method
was to implement a procedure whereby a test film was first framed
against a fixed point of reference (one of those Rank tube faceplate
graticules works quite well) before centering the scans.

 

Another method involves disabling the framing buttons (on Pogle).

 

I believe an idea toyed with by the CRT telecine manufacturers was to
apply picture steadiness correction to the scans with, or instead of the
capstan servo, and such a device could minimize the effect of reframing
whilst running. The issue here of course is that a closed-loop servo
correction applied to the scans would have been rather difficult to
implement, and the result will never be perfect.

 

Laurence Claydon

Bell Theatre Services Ltd

Borehamwood, UK

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