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1953-54 Theatre Catalog, 11th Edition, Page 281 (245)

1953-54 Theatre Catalog, 11th Edition
1953-54 Theatre Catalog
1953-54 Theatre Catalog, 11th Edition, Page 281
Page 281

1953-54 Theatre Catalog, 11th Edition, Page 281



A Comprehensive Analysis of the Development, Manufacture. and Use of the Metal Motion Picture Projection Reflector

November 10, 1934, saw the birth of an idea that was destined to give to the motion picture industry a new and much needed item for projection equipment.

The trend towards more and better light on the motion picture screen had, at that time, sparked the development of the Superex are, which was a great improvement over the low intensity arc, not only in quantity of light, but in quality as well.

However, this more volatile are brought with it a new problem. Its discharge of molten copper, hot carbon particles, and core gasses, as well as the additional heat due to the higher amperage it worked at, in many cases caused extreme pitting, cracking, and breakage of the back silvered reflectors in use at that time.

The result was a demand for a better reflector; one that would withstand this beating year in and year out; a reflector made of metal tarnish, or break.

This challenge was taken up by the author and the late Charles E. Shultz. They began work on the idea with some antiquated machine tools, found in a local welding shop. The project was not an easy one because for one reason, no such precision metal reflector had ever been made and consequently reference data was non-existant. Extensive experimentation with various metals and reflective finishes, as well as much development work in perfecting methods of fabrication. resulted in the creation of a commercially practical metal projection reflector. Field testing in theatre booths further proved the worth of this new product. A company was formed for the purpose of producing this new reflector and shortly thereafter a rugged, durable, all metal motion picture projection reflector was put on the market.


This new reflector was constructed of a heavy brass base with a rhodium finished front surface. Although rhodium

PRINT A (lett) IS A FINISHED all metal reflector which has been carefully corrected to elliptical curvature that will give best results. Print


that would not pit,.


Presidvnl. Meyer-Shula, Inc.

BRIEF: As motion picture techniques have improved . . . they have also made more demands on the equipment that is required to project the film . . . Lighting . as perhaps at no other period in the history of motion pictures is of major import . . . One of the vital parts of the projection lighting equipment . . . is the reflector . . . This article . . . authored by one of the original designers . . . gives the background and development of the metal reflector . . . It describes how and why this type of reflector was designed . . . its manufacture . . . and the various tests that are performed to insure the accuracy and perfection of the finished product.

was not as reflective as silver, a method was devised whereby the redector would produce as much delivered screen light as the average back silvered reflector. This was possible only because the reflector curvature was constructed mechanically by precision machine shop procedure. Its elliptical curvature was so highly corrected that it utilized more of the light from the are by way of aperature spot concentration.

In a motion picture projection reflector, precision of curvature is essential. Lack of precision creates a loss in efiiciency, introduces unwanted color and cuts down on the depth of focus.

Precision Necessary

There is a definite degree of precision necessary in a projection reflector, if it is to operate efficiently. The metal reflector was designed along this line of reasoning, and has for the past 18 years been carefully manufactured to the close tolerances originally decided upon. By strict adherence to these tolerances, it was possible to give; pure white light,

free of all unwanted colors; true color rendition of color film; maximum depth of focus; and standardization in manufacture, guaranteeing interchangeable reflectors and invisible changeovers.

To illustrate the difference between precision and non-precision, we accompany this text with the two unretouched photographs, A and B. These are pictures of a screen that has been laid out in three-eighth inch stripes, spaced six inches apart. The pictures represent reflections of the striped screen as seen in two diHerent metal reflectors. Because of photographic angles and distances necessary in obtaining these pictures, the stripes are, of course, curved.

Print A is a finished precision allmetal reflector, taken from a stock run. In this photograph the stripes on the screen are reflected in a true, symmetrical pattern, evenly spaced and unwavering from edge to edge, of the reflector. This reflector has been carefully corrected t0 the required elliptical curvature and is an excellent example of precision.

Print B is a polished ubank" that has not as yet been put through the curvature correction operations. Although it has been stamped to curvature with accurately made dies, the photograph plainly shows the inaccuracies that still remain. These variations from the true ellipsoidal curvature have horribly distorted the stripes. In a lamp, this reflector "blanktl would disperse the focused direction of the arc, causing a terrific loss in splash light on the cooling plates, the cone, and even within the lamp. It would also pick up all the unwanted colors of the arc and the glowing carbons. It would be practically useless.

Curvature correction, as already stated, is the deciding factor in controlling correct color rendition and working range. Unwanted color, differing from that of the crater, appears in the following manner: Let us suppose we are imaging the crater of a simplified high-intensity type carbon are as shown in Figure 1, in which the colors of the arc are divided into three zones, marked C, A and B.

B (right) is a polished "blank." that has not yet been put through the curvature correction operations. As it is it would be useless in a lamp.
1953-54 Theatre Catalog, 11th Edition, Page 281