[tig] stability of scanning-telecine

john.pytlak at kodak.com john.pytlak
Mon Aug 30 13:22:06 BST 2004


One thing to bear in mind is the principle of "cancellation" --- film 
systems should ideally be designed so that the film is positioned in the 
same way during both exposure and printing, such that the effect of any 
dimensional variables are "cancelled" or minimized.

Most 35mm cameras use a full-fitting registration pin to precisely 
position the film, both vertically and horizontally.  So optimum 
steadiness is achieved by positioning it during printing or transfer using 
a full-fitting pin in the same perforation that the camera did, relative 
to each frame.  So for 35mm film, edge-guided systems (continuous contact 
printing or continuous motion telecines) can provide excellent lateral 
steadiness, but not as good as a pin-registered system.

In 16mm cameras, the film normally is pulled into position by a claw, and 
vertically positioned by a positioning pin.  But lateral positioning in 
the camera is normally done by an edge guide against the reference edge of 
the film (the perforation side of film perforated 1R-2994).  So optimum 
lateral steadiness (minimum weave) is theoretically achieved in an 
edge-guided system that positions the processed film in the same way the 
camera positioned the same piece of unprocessed film -- edge guiding the 
reference edge.  Hence, excellent lateral steadiness is achievable for 
16mm film on edge-guided machines.

Kodak published an excellent technical paper on the subject:  "Challenges 
to the Concept of Cancellation", by Roland J. Zavada, SMPTE Journal, 
December 1981, Volume 90, p1173.

John
(signed by:)
John P. Pytlak
Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, New York 14650-1922  USA
Telephone: +1 585 477 5325
Cell: +1 585 781 4036
Fax: +1 585 722 7243
e-mail: john.pytlak at kodak.com
website: http://www.kodak.com/go/motion



--

On Mon, Aug 30, 2004 at 12:44:05AM -0700, Marc Wielage wrote:

> The reality is that I think 16mm is steady enough on a Spirit or 
C-Reality
> that I've never heard any complaints about image steadiness on these
> machines. 









More information about the Tig mailing list