Theatre Design & Technology - Oct 1966 - 46

single-ended lamp, which also has other applications in
other units. It allows us, without increasing the size of
the fixture to a great extent, to "wrap" the fixture around
the filament more efficiently and to increase the efficiency by gathering more Iight in the reflector where it is
controlled. We might like to do away with all direct
emanation and have all the light controlled, as in any
lighting unit, by means of lens and/or reflector. By eliminating as much as possible of the direct emanation
in this kind of an unit, you can preserve the softness of
the shadow.
It is a soft shadow: this is a frosted lamp. With a clear
lamp naturally it is not quite as soft, but it is much softer
than if we had a great proportion of the emanation from
the filament coming out directly, rather than being reflected off a large surface.
The basic philosophy of fixture design (no matter what
the unit, whether a scoop, a fresnel lens unit, or any new
unit that may come up tomorrow morning) is controloptical control, in any unit. By putting as much of the
reflector or any other optical component around the filament and controlling the light, we get more efficient
use.
Where you have a reflector and a filament in this relative
position, you have control of a much greater proportion

of Iight by means of the reflector. This is our approach
in this kind of unit: to the most light into the reflector
and then out.
We have accompl ished another objective with the singleended lamps of this type (not to mention others that
are available now, and hopefully many more in the near
future, of a wider rangel. This same lamp (not the frosted, but the clear glass version) is interchangeable in
certain existing equipment which gives immediately, without obsoleting equipment, the advantages of the quartz
lamp.
One of these advantages is approximately four times as
many lumen hours. That figure varies from lamp to lamp;
but it seems to be a kind of a rough guide, looking at
several representative lamps: approximately four times the
lumen hours of conventional lamps.
There is no great mystery about a scoop. The thing that
I want to stress at this time is the application of a single-ended quartz lamp in this type of unit and in other
units where we are making a more efficient use of the
output of the filament in an optical system. The means
are there to wrap the controlling element (in this case
the reflector) around the filament and use wholly-controlled
light coming out, rather than having some partly-controlled with a large proportion of direct emanation.

Sodium Iodide Lighting Equipment
Robert Benson

I.R. CODE: equipment - lighting - instrument

For several years, Kliegl has been working with quartziodine lamps in striplights and cyclorama lighting. As
the compact-source lamps became available, we began designing fresnel spotlights and ellipsoidals around the new
units. Aside from the known advantages of the new lamps
(longer Iife, smaller size, lower cost, unrestricted burning
position, etc.l, important advances were made in equipment design and performance as well.
For theatrical applications we designed the new six inch
fresnel spotlight (No. 3506 series) that uses single"nded lamps in the 2 50 watt, 500 watt, and 750 watt
sizes. For those applications (in television) where color
temperature is a special consideration, the units can be
provided with different socket arrangements to take doubleended lamps like the short-life 650 watt lamp (No. 3507
series). Both units have spindle focussing, and significantly improved performance.

Some time ago, one of our customers came to us for a
relatively simple, 1000-watt incandescent follow spot to
replace the 10 ampere arcs he was using. He wanted a
unit as bright as he already had. Well, we didn't quite
achieve that, but we did come pretty close.
The spot was meant to be a narrow beam unit, and consequently has no spread lens in it. It is not meant for
full stage coverage, but finds greatest use as a personal
spot for one, two or three people, and at considerable
distances. The unit contains a dousing iris, framing shutters, and an internal color boom which was very successfully tested with both plastic and gelatin color media. A
small blower keeps the unit cool to the operator's touch.
Re-Iamping is done from the rear. An adjustable lens
tube permits the selection of soft - or hard - edge beam
characteristics.

USITT

THEATRE DESIGN AND TECHNOLOGY

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