Theatre Design & Technology - Oct 1967 - 46

The newness of this source creates a dilemma for the user.
The advantages of the source have created a great interest
in its use, but can it be utilized in existing equipment? Are
there advantages in utilizing this source in new equipment?
Is the source sufficiently developed to merit purchasing
equipment which util izes it? Are both this source and the
new equipment developed for it compatible for use when
mixed with existing equipment utilizing conventional lamps?
The first question is the most difficult to answer. Some
tungsten-halogen lamp types have been developed to be
direct replacements for existing lamps. These often have an
increased cost which is directly proportional to the added life
of the lamp and provides no increase in performance until
the maintenance decrease (bulb blackening) in the standard
lamp takes its toll. Adaptors have also been developed
which make it possible to utilize tungsten-halogen lamps in
existing equipment. These adaptors sometimes go so far as
to replace the socket, reflector and lens in a fresnel fixture;
thus only the housing is saved. The adaptors can produce a
change in the character of the light output (such as a
change in uniformity of the beam) which makes their usefulness questionable. While offering improvements, the use of
tungsten-halogen lamps in existing equipment provides few
major advantages.
New equipment designs utilizing tungsten-halogen lamps do
provide major advantages. The small bulb size allows the
development of smaller equipment. This small equipment,
however, will have higher temperatures for the housing when
compared to larger standard equipment of equal wattage.
The tungsten-halogen will generate the same heat as standard incandescent lamps so with a reduction in housing surface area, the heat per unit area must increase. These smaller units can equal the performance of the larger units they
replace and in many cases can out-perform them. If the
equipment size is not reduced, definite performance increases
can be obtained. This is true because the small bulb and.
compact filaments allow the design of new optical systems
which increase the utilization of light from the lamp and,
therefore, the performance of the equipment. Adding the increased lamp life or light output to this increased performance and then holding it constant throughout the life of the
lamp, makes the use of new equipment designs a major
advantage.
The increased temperatures of the small size equipment developed around tungsten-halogen lamps and the newness of
these lamps could prompt a wait-and-see attitude towards
this new development. This is now not justified. The lamp
development has progressed to the point where there are
families of lamps containing variations in lamp life and wattage. These have allowed the development of equ ipment
that is as, if not more, versatile than the equipment they replace. The equipment manufacturers have utilized these
families of lamps to develop new equipment types which
provide the increased performance obtainable from these new
lamps. This equipment has been designed with a recognition
of the high temperature limitations of the lamp and with
materials and methods which allow increased housing temperatures without causing problems. Of course, during the
early developments unexpected problems did occur, but these
have been corrected. The availability of families of lamps
and equipment designs which are debugged eliminates any
further need for a cautious attitude. Since it is unrealistic
to expect that existing equipment will be discarded and replaced with all new equipment, the question of mixing types
must be answered. First it must be stated that an economic
analysis will show that a new unit with a long-life, tungstenhalogen lamp can equal the performance of present shortIife lamp units and pay for itself in a few years through reduced relamping costs. To obtain uniform performance in
mixing types, it is necessary to utilize the new equipment

in one location and the existing equipment from another location. Direct mixing is possible, however, by utilizing differences in wattage and! or lamp life. One procedure for
adding the new equipment is to purchase it in groups to
replace existing units which can then be relegated to specialized occasional uses.
A 50-50 mixture in old and new equipment, the latter providing increased performance through power savings, results in
a more versatile system with no increase in control or operating costs. The dilemma that the user has been in, as the
switch has been made to these lamps and new equipment,
has now been solved. The user can now prove this to himself by evaluating the results obtained with the new equipment versus his present equipment. It is always true that
some manufacturers will make unrealistic claims and not
stand behind their product. This product is, therefore, no
different from any other in that the user should evaluate
what is available, determine what he wants, and then purchase it from a reputable manufacturer.
Just as the tungsten-halogen lamp is replacing the standard
incandescent lamp, there are arc-discharge lamps being developed which will replace carbon-arc sources and for use
in special lighting now using other lamps. The short arc,
high pressure, xenon lamp is one of these. It has already
replaced the carbon-arc in some motion picture projectors,
and it is moving into follow-spot units. It could also be useful for other projection systems, such as scenery or special
effect projectors. These lamps have some potential for dimming; however, this will add additional cost to the ballast
and power supply systems required by these already very
expensive lamps.
Other arc discharge lamps which appear to offer future potential utilize metallic additives to the arc of both highpressure and low-pressure type lamps. These metallic additives provide changes in the color properties of the arc.
Again the required power supplies and ballasts present
limitations to the lamp usage. One major advantage to the
lamps is their ability to produce as much as 100 lumens per
watt output as compared to 18 to 34 lumens per watt for
incandescent lamps. This makes it desirable to utilize these
lamps as a replacement for incandescent lamps; however,
dimming and power supply requirements present another
major concern.
During the next decade the development of arc-discharge
lamps will add to the present tungsten-halogen lamps to replace most present sources utilized in the theatre. New techniques in lighting will undoubtedly result from the use of
these sources. The arc-discharge lamps will probably replace
even the tungsten-halogen lamps in some instances. This
technology advancement need not create a dilemma for the
user so long as the developments are followed closely,
evaluated thoroughly, and the equipment purchased from
proven manufacturers.
Remarks
by Joseph S. Kaming, P.E.
What's new in technology is not solely innovation, but also
admonition. A framework of law and strictures of liability
are finding new application to the theatre. The combining of
creativity and regulation produces explosive type of product.
But with theatre construction expanding, more and more
creativity and regulation are being mixed. I would advise
that those involved in theatre or theatre component construction exercise certain precautions.
As you know, there are such things as professional registration laws and design liabilities. It is better not to use a
courtroom as a seminar to explore the intimacies of those

ruillD

THEATRE DESIGN AND TECHNOLOGY

Table of Contents for the Digital Edition of Theatre Design & Technology - Oct 1967