6.3 What does a negative cutter do? (Film Laboratories)
Description
This article is from the rec.arts.movies.tech FAQ, by Scott E. Norwood snorwood@nyx.nyx.net with numerous contributions by others.
6.3 What does a negative cutter do? (Film Laboratories)
6.3.1 General Information on Negative Conforming
After a workprint (or videotape transfer of camera negatives) is
edited, the original camera negatives must be matched (`conformed')
back to the workprint, so that prints can then be made from the
negatives. This is a job done by a negative cutter, who uses the `edge
numbers' or `keycodes' printed (by the manufacturer of the raw stock)
on the edge of the camera negative and then printed through on the
workprint. These numbers are printed every 20 frames in 16mm and every
16 frames in 35mm, and are the reference points for the negative
cutter. `Keycodes' are simply barcode versions of human-readable edge
numbers, and permit the cutting of negatives to match edited videotape
transfers from negatives (provided that the transfers have `window
burns' in the corner of the picture, showing the proper keycode
numbers for the film being transferred).
6.3.2 A & B (& C) Roll Conforming and Printing
Films in 16mm and sometimes 35mm are cut into so-called `A & B rolls,'
in a `checkerboard' fashion in order to ensure that splices will not
appear on the screen when the prints are projected. This technique is
best described with the following diagram:
------------------------------------------------------------------
'A roll' | <----scene 1----> | <----black leader----> | <----scene 3----> |
------------------------------------------------------------------
------------------------------------------------------------------
'B roll' | <--black leader-> | <-------scene 2------> | <--black leader-> |
------------------------------------------------------------------
The print film is then run through the printer (at the lab.) thrice,
first exposing it to the `A roll,' then rewinding, then exposing it to
the `B roll,' then rewinding, then exposing it to the soundtrack. The
completed print (if printed properly) contains all scenes in order
without visible splices in between, as well as an in-sync soundtrack.
If white titles are needed, then the print film is run through again,
this time being exposed to a `C roll,' containing main or subtitles.
Fades and dissolves (cross-fades between scenes) are made at this time
too, using either a punched paper tape or notches in the edges of the
negatives as cues.
This A & B roll method is not always necessary for 35mm, as enough of
the area around the frameline is masked off in projection to permit
splicing the film negatives into a single strand which can be printed
in one pass through the printer, instead of two. The A & B rolls are
necessary, though, for dissolves between scenes, and for superimposed
images.
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