Consideration has been given so far to errors within a
single panel only. Taken alone these errors have been present all along in
single panel systems and, great as they are, the pictures have been adequate.
Taken in a multipanel system we have already seen how some previously minor
defects now appear as disturbing hot spots or scalloped edges which disturb the
continuity of the picture as a whole. Now it is necessary to consider these
errors which make one panel different from another. Here the same three pieces
of equipment are the major contributors to error. The negative and positive
film strips and the processing can also be included, except that the procedures
employed in selecting, storing, handling and processing these strips has
minimized these sources of error to a point where they are such minor
contributors that they need not be considered until very great improvement is
made in the other pieces of equipment.
Negative material is selected and used in groups of three
adjacent strips taken from the wide master roll. They are kept together at all
times and are processed in the order A B C so that processing time between
panels is kept below ten minutes. A group is never separated and processed at
different times, processing is begun only after control shows that the
processing is quite stable. The same general procedure is used in the print,
with the additional step of pretesting each individual roll, ruthlessly
rejecting rolls and returning them to general supply for slightest reason.