A printer failure which is disconcerting and often difficult
to trouble shoot is a flash in the matchline at a scene change. Usually the
matchline starts dark and a very short period of time later it corrects itself.
This is usually caused by a solenoid releasing too slowly. It is difficult at
times to note this in checking the printer operation since the time involved is
so short. As the condition progresses and the flash becomes longer it is easier
to locate the faulty solenoid. If lubrication with a dry lubricant such as
molybdenum disulfide or Molycote (a liquid lubricant must never be used) does
not correct the trouble, the plunger should be checked for burrs, otherwise the
solenoid should be replaced.
The feather step schedule should be checked with the
microscope occasionally and corrections accurate to at least ¼ scale division
should be made. Due to the symmetry of operation the sum of the readings for
steps 1 and 6, 2 and 5, 3 and 4 should be a constant to insure proper blending
for all feather schedules.
It should be noted that for the six focus steps there are
only three feather schedules available, so that each feather schedule must
handle two focus steps. It should be noted that it is impossible to locate any
feather schedule so that it does not give trouble (show the camera vignette)
for some camera focus positions. (Fig.9). In fact some of the final feather
schedules do not even look like they are best compromise positions when
compared to the overlap schedules for final camera alignment. These changes
become necessary when a schedule based on the data was tried out and it was
found that too many of the scenes showed camera vignette for various reasons.
As a result, the final schedule was gradually adjusted to improve the bulk of
the scenes as much as possible while harming the remaining scenes as little as