Theatre Design & Technology - Fall 1979 - 48

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Telephone 312-971-0855

Letters

Photometric Data Sheets
Although I heartily agree with the thrust of Mr. Bullocks article,
"Using Photometric Data Sheets" (Spring, 1979), to help the user
decipher the data presented by manufacturers, I must call attention to
several inaccuracies and rather vague statements.
On p. 24, Mr. Bullock states, "The illumination will vary with the
distance.... " This is properly stated as " , ..will vary inversely as
the square of the distance."
Later in the same paragraph he states, "after the light strikes the
floor plane the illumination drops to.... " The illumination doesn't
drop, rather it is being calculated in two different ways. The higher of
the two values is calculated perpendicular to the beam axis and the
lower, parallel to the floor.
Although his example makes the point that illumination drops as the
plane illuminated is turned from perpendicular to the beam axis, I am
afraid the cold mathematics are somewhat unrealistic. Rarely are we
concerned with lighting an actor lying on the floor or the floor itself.
More typically, we are concerned with the actor moving through the
space and formulae will not tell us what his appearance will be.
Perhaps most important of all is Mr, Bullock's discussion of overlap, as illustrated in Fig. 2. If he had plotted the same figure using the
more useful Cosine Distribution setting for the units, which provides Y,
of maximum intensity at ¥. of the spread, his diagram would show almost ideal overlap for smooth area lighting. Several manufacturers
are now providing data for Cosine Distribution which is most useful for
average area lighting.
Finally, I think his phrase, "the strain found in artistic lighting.....
is a most unfortunate choice. I would not like to be in Mr. Bullock's
shoes when he has to defend the premise that artistic lighting causes
strain for the audience.
Charles Levy
Executive for Theatre Services

Strand Century, Inc.

-----News
San Francisco Performing Arts Center
The first phase of the San Francisco Performing Arts Center project is nearing completion-a 38,000 square foot extension to the War
Memorial Opera House. The 3,000 seat Opera House was completed
in 1932 and has served as the home for the City's Opera, Symphony,
and Ballet companies.
The exterior of the extension, which had to match the original building exactly, is now complete. The interior of the building, with its large
set storage bays, rehearsal facilities and administrative offices, is expected to be completed by the end of July.
Visible in the center of the extension is a large side door which provides easy access to scenery trucks for major Opera and Ballet productions. Trucks can drive right into the Opera House at stage level;
scenery can be unloaded and set in separate storage bays along the
rear of the extension.
This part of the PAC project cost approximately 6 million dollars.
Funding for the Opera House extension was accomplished with major
gifts from Sponsors of the San Francisco Performing Arts Center,
Inc., the Kresge Foundation, and the United States Department of
Commerce, Economic Development Administration.
A 3,OOO-seat concert hall, to be named the Louise M. Davies Symphony Hall, is currently under construction across the street from the
Opera House and is expected to be completed a little more than a
year from now, according to Samuel B. Stewart, President of Sponsors. Stewart reported the fund drive for the PAC, which he heads,
has raised over $34 million of the $37.4 million goal.

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(213) 347·8360

Table of Contents for the Digital Edition of Theatre Design & Technology - Fall 1979