Theatre Design & Technology - May 1965 - 25

simultaneous with the establishment of light
levels with subsequent use of the record itself
to re-establish those levels. By making the
record of each cue an accurate representation of
all dimmer levels rather than merely the changes
in setting, these systems have immeasurably
speeded up the lighting rehearsal process and
increased the reliability with which an operator
can be expected to reproduce the lighting for a
producti on.
The recording of cues is essentially a process
of committing information to some device which
will "remember" until the information is needed.
Typically, the dimmer settings, switching and
the gross timing of a cue are "remembered" by
being written down while the precise timing is
remembered by the operator. Using our present
methods, it is not possible for live productions
to be so completely recorded that an operator
skilled in the use of the equipment (but without
previous knowledge of the lighting effects)
can accurately reproduce even the lighting established in rehearsals, much less create an
optimum presentation of the lighting design. Here
again is raised the question of standardization,
not only of control equipment but of cue sheet
notation, which makes possible the substitution
of operators without detriment to the performance.
We must admit that the personality of the operator is evident in each performance and that the
replacement of an operator, just as the replacement of the actor, changes the performance to
some extent. Although some porti on of the ti ming
of cues and operation of the control system must
be left to the memory of the operator, development of recording methods which leave the least
possible routine information to human memory
wi II release the operator's attention from the
mechanics of reproduction and allow him to concentrate on creation of the lighting design.
During the performance, the operator must divide
hi s attention among cue sheet, controls, and performance. The cue sheet must not only correspond as closely as possible to the arrangement
of controls, but to the performance as well.
Placement of the cue sheet so that minimum head
movement is required to shift attention from performance to cues is helpful. Even more helpful
would be superimposition of the cues on the
performance, perhaps by projecting cues on the
control booth window or using a television monitor.

PROTECTION AGAINST ERRORS
Three primary goals for system design have become apparent in the discussion thus far-the refinement of devices for more precise control of
light including properties other than intensity,
flexibility to allow for a reciprocal action of
light with other elements of production, and
simplicity of primary controls to permit concentration on the performance rather than the mechanics of effecting each cue. A fourth goal must
now be considered which generally compromises

MAY, 1965

achievement of the first three: all portions of
the control mechanism must function accurately
and reliably at all times. Although our scale of
values may count the best possible performance
of a dramatic presentation as of less importance
than the correct launching of a rocket, still there
may be a second chan ce for the rocket, but
never for a dramati c performance before a
particular audience. Such dependability is far in
excess of that imposed on virtually any other
control system.
So long as systems are custom made, each to
different specifications, advance estimates of
dependability are difficult to make and impossible to prove. As a result, we often complicate
the equipment with features of questionable desirability without any assessment of the consequences in reduced dependability. The reliability of a multipart system is the product of the
rei iabi Iities of the component parts so that as
systems become more complex, their overall reliability is reduced. Some reduction in reliabi lity may be justified by significant gains in flexibility, control refinement or simplicity of primary controls, but at the same time every effort
must be made to decrease the unreliability of the
individual parts of the system. Since it is not
always practical to do the development work to
increase dependability to optimum levels, it is
essential that the machine include devices to
check automati cally for errors originating either
in the machine or in the operators, for communicating these errors for correction, and for bypassing any portion of the system found to be
defective.
At the present ti me, i Ilumi nated pi lot lights are
virtually the only device used for error checking.
As these are normally installed, however, they
function more as monitors of operator error than
of machine error, since operation of the pilot
light is seldom dependent on functioning of the
electrical circuits or of the lighting instrument.
Dimmer readings may also give an indication of
error, but the use of masters and submasters
makes the interpretation of dimmer readings difficult under performance pressures. If machine
checking is to have opti mum effect, the mon itoring devices must feed back from as close to the
instrument as possible, and must be capable of
indicating the sources of error in switches, dimmers or controllers.
In every system there must be alternative methods
for carrying out the Iight plot in case of fai lure
of the sophisticated system. Change from one
control means to another must be effected simply
and instantly. The secondary control system
must itself be sufficiently complex to permit
practical execution of the lighting changes required of the primary system, the differences being in difficulty of execution or number of operators required. The number and type of standby
controls is dependent on the form of the primary

25
Table of Contents for the Digital Edition of Theatre Design & Technology - May 1965
