THE general use of panchromatic negative film for the taking of motion pictures has introduced into the studios new problems in general illumination of the sets which in time will, no doubt, necessitate a change in present day lighting equipment.
The purpose of this paper is not to deal in technicalities or enter into a discussion as to the relative merits of either type of lighting; the incandescent, Cooper Hewitt, or arc light equipment, but will deal only with the development of the use of incandescent tungsten lighting equipment in Hollywood studios up to the present time.
It might be well, however, to review the early development of the high wattage incandescent lamps of the type used in the studios at the present time. It was around 1920 when Maude Adams first appealed to the General Electric Company for aid in developing a lighting unit which would enable her to successfully proceed with a new process for the taking of motion pictures in color. This was what really brought about the development of the 30,000 and 10,000 watt incandescent tungsten lamps.
Sometime later the Harrison Lamp Works of the General Electric Company made up some of the 3,000, 5,000 and 10,000 watt lamps at the request of the Eastman Kodak Company for use in their experimental motion picture studio at Rochester, New York. The results of their experiment with these lamps are covered in part by L. A. Jones' paper on "Incandescent Tungsten Lamp Installation for Illuminating Color Motion Picture Studios" as presented at the September 1925 meeting of your society.
With the introduction of panchromatic film the cinematographers made considerable use of low wattage incandescents for close-up work. The results obtained in this work were so satisfactory from the photographic standpoint as to lead to a desire on the part of the cinematographers to use this source of light to illuminate their entire set as well as the "close-ups."
It was at this point that they found there was no commercial equipment available to substitute for their present "arc spot" and "GE suns." The first equipment to replace the GE High Intensity 120 ampere spots and GE 150 ampere High Intensity Suns was furnished by Mole-Richardson, Incorporated, Hollywood, California, at the request of the Metro-Goldwyn-Mayer Studios through their chief engineer, Lewis Kolb, and consisted of ten 24 inch standard "sun" housings with pedestals equipped with a 24 inch long focus parabolic mirror with a base suitable for the 10,000 watt lamp.
In designing this equipment we were somewhat handicapped by the fact that it was necessary to follow certain specifications which called for the housings to be so designed as to be adaptable to both the 150 ampere high intensity arc elements as well as the 10,000 watt incandescent lamp.

Fig. 1. Double incandescent broadside lamp.

The efficiency of this unit could have been increased considerably, no doubt, if this equipment had been designed especially for the 10,000 watt incandescent lamp. These lamps have been used successfully in regular production. In some cases they are used on the sets in combination with the regular arc light equipment and in other cases used only with other incandescent lights. In both cases they have proven very successful.
About the time Metro-Goldwyn-Mayer were working with the 10,000 watt incandescents lamps, Warner Bros. Studios, under the supervision of F. N. Murphy, their chief engineer, were producing a picture called "The First Auto," using incandescent lamp units of not over 1,000 watts, and they used in a few cases some arc spot equipment. After viewing some of the scenes from this picture, I personally feel that a great deal of credit is due them for their aggressiveness.

Fig. 2. Sun arc housing fitted with incandescent lamp.

In Preparing the picture "The West Pointer," the De Mille Studio found it necessary to send a company on location to the West Point Military Academy at West Point, New York. It was found practically impossible to take the necessary arc light equipment to photograph the many interiors on the campus grounds. By the time the West Point Company was ready to leave, there had been developed a suitable lamp for spot light work, 18 inches in diameter, using a spun metal or glass parabolic mirror, and equipped with either a 2,000 or 3,000 watt incandescent lamp. There was also used in front of the incandescent lamp a condensing lens to collect the light from the front face of the filament. By independently focusing the lamp toward the mirror so as to secure the size of spot required and then focusing the condensing lens with respect to the lamp, the spot was intensified, and also the so called "ghost" which is somewhat pronounced when spreading a beam of light from parallel rays was cleared up. Tests were carried on at the De Mille Studio under William Whistler, chief engineer, and Peverell Marley, chief cinematographer, who photographed "King of Kings," and as a result of those tests it was decided to use incandescent equipment for this particular location.
The equipment taken to West Point by the De Mille Studio consisted of:

10-18 inch MR Incandescent Sunspots
20-Double MR Incandescent Broadsides
15-Single MR Incandescent Broadsides
6-Condensing Lens Spots

The 18 inch Sunspot used a 2000 watt G 48 lamp, the double broadside used two 1000 watt T-20 lamps, the single broadside used a 1000 watt G 40. With this equipment they photographed all the locations except the chapel and the formal dance, and on account of the size of these two scenes it was necessary to use additional arc equipment, as no more incandescent equipment was available.
In addition to the above equipment the De Mille Studio has equipped every company operating in their organization with incandescent lighting equipment for close-up work. Before starting the picture "The Rose of Monterey" around June first of this year, Lee Garms, cinematographer of the First National Picture Corporation, working with Walter Strohm, chief engineer, made tests with the incandescent tungsten light and panchromatic film with the result that 75% of the entire production of this picture was photographed with this type of lighting. Arc light equipment was used where the sets were of such proportion that the available incandescent equipment would not entirely cover them to advantage. The operating costs of the electrical department for this particular picture with incandescents amounted to about 40% of the cost had the picture been taken with arc equipment.
From the results obtained in "The Rose of Monterey" the First National officials were encouraged to such an extent that they purchased twenty-four additional 18 inch Sun Spots and other flood light equipment to fully equip one unit which is now in production making the picture "Man Crazy," photographed by J. Van Trees.
The second company to go on location equipped entirely with incandescent lights was the Sam Rorke unit of the First National starring Will Rogers in "The Texas Steer." During September this company will be shooting locations around the National Capitol at Washington, D. C.
Tests were made also at the Universal Picture Corporation Studio by Roy Hunter and Frank Graves. The results obtained from the incandescent lamps were so satisfactory that they now have on order enough equipment, consisting of the 18 inch MR Sunspots, broads and flood lights, to completely equip one company for this type of lighting.
After several weeks of testing and experiment on the part of individual cameramen, assisted by R. E. Nauman, chief engineer of the Famous Players-Lasky Studio, during the latter part of August a meeting of the cameramen was called at which the writer was present and discussed the different incandescent lighting units. It was unanimously decided that the results obtained from their tests justified their purchasing considerable incandescent equipment in order to carry on further tests and to carry on certain of their regular production work with this type of lighting.
The Studios' officials, cinematographers, and electrical supervisors are to be commended for the manner in which they have grasped this new form of lighting. All of them have manifested great interest, and in every case the writer has received the greatest amount of cooperation possible when running tests or making demonstrations. Indebtedness to The General Electric Company through F. E. James and E. P. Mackee of their Los Angeles office is hereby acknowledged because of their assistance and cooperation in this new branch of studio lighting.
It must be remembered that while the incandescent tungsten lamps have been used for some time for "close-up work" and "stills" their use in the studios for general motion picture production work has been limited to only about nine months.
Reviewing this article and analyzing the work being done by each studio, one can easily see that a great future is ahead for the incandescent equipment. It may take considerable time for the different departments, such as the electrical, photographic and laboratory, to adapt themselves to the new conditions, but this is gradually being done, and I do believe greater strides will be made in incandescent tungsten lighting in the near future.

DISCUSSION

Mr. Beggs: About a year ago I tried to calculate the theoretical costs of lighting a studio with mazda lamps. At that time it was felt that mazda lamps were impossible, but calculations made theoretically showed that the costs were approximately the same as for arcs. Now, the film is a little faster for incandescents, and labor costs have been calculated closer, so that the figures I published at that time do not necessarily apply for mazda lamps although at that time it was about a toss-up for cost for lamps, fixtures, and labor. Since that time we have been asked to produce a metal reflector. It is not so efficient as silvered glass, but it is indestructible, and chromium has been found to be the most successful plating. The advantages are chiefly that it is easily cleaned. Chromium is going to be very popular as a surface plating material. Probably you noticed that the Kodascope projector used it, and it is being used in the lighting field for industry.
I should like to ask Mr. Farnham about the over-voltage operation of lamps. Any of these incandescent lamps can be burned with over-voltage with reasonable assurance that it will give fair photographic performance, but it may destroy the lamp, and there should be an agreement among studio engineers, I believe, concerning the exact over-voltage which should be used.
Another point is the avoidance wherever possible of these extremely expensive lamps; $175 is the present price of the 10 kilowatt lamp with 100 hours' life. The same light flux can be obtained from ten 1000-watt lamps for $2.50 each, which gives a different total price, and it seems unreasonable that studio engineers should insist on using the very expensive lamps. I think they might get together a symposium on the use of incandescent lamps for studio engineers.
Mr. Farnham: With reference to operating lamps at an overvoltage, the studios now working with incandescent lamps operate them from the same source of supply that they operate their arc equipment, and hence it is not practicable to operate the lamps at other than the voltage of the circuit without causing trouble on other sets that are using the same source of supply.
The light output of an incandescent lamp operating at from 250 to 400 hours' life has the correct color characteristics for use with Panchromatic film, and if they were operated at an over-voItage, a relatively greater increase in the blues and violets would result, and the color rendition would not be correct. Instead of over-voltaging the lamp at the time the picture is being taken, I suggest the practice of operating lamps at an under-voltage during rehearsing and at times when it is not necessary to expose the film, and then before the picture is to be taken the lamps should be brought up to normal voltage.
In considering future practice where the lamps are operated directly from alternating current source, it would be a simple matter to install a portable induction regulator between the supply circuit entering the building and the particular set on which it is desired to control the current. This would make it possible to operate the lamps at an under-voltage until the time to make the picture, when they could be quickly brought up to full voltage. The use of this device would likewise permit bringing lamps from total darkness to full brilliancy or from full brilliancy to total darkness for special lighting effects, duplications of sunrise and sunset scenes, etc.
With reference to Mr. Beggs' point that it would be more desirable to use ten 1000-watt lamps instead of one 10,000 watt lamp; this might be practical in some cases, but there are many instance's where it is desired to create the effect of strong sunlight streaming in through a window or door, and the intensity of this source must be considerably greater than that of the other light source illuminating the set. For this purpose a single source of high-wattage such as a 10 kilowatt lamp would be required. Ten 1000-watt lamps would be quite out of the question because they would create ten individual shadows and spoil the illusion of sunlight.
Mr. Isaacs: I should like to ask Mr. Farnham what the advantage would be of cutting back from DC to AC when the latter gives flicker.
Mr. Farnham: A mazda lamp operates equally well on alternating or direct current. The studios would naturally not wish to discard their existing motor generator sets, but as the present equipment becomes obsolete or greater lighting capacity is required, they would gradually shift to AC operation and thus remove the heavy investment in substations and the necessary attendant which rotating equipment requires. With regard to flicker on alternating current circuits, due to the relatively small size filament wire of the 100-watt lamps and those of lesser wattage, there is a noticeable flicker when the lamps are operated on 25 cycle currents. On 60 cycle currents this flicker cannot be detected with the eye, but it can be observed by stroboscopic methods. However, as we increase the wattage of the lamps and hence the diameter or mass of the filament wire, the heat storage capacity of the filament becomes greater, and the fluctuations of the light, due to the cyclic variations of the current, becomes less. From tests which we have conducted using a special stroboscopic device, we find that fluctuation of the light disappears with lamps of 500-watt, 115-volt ratings and above on 60-cycle circuits. In the studio district, 50-cycle circuits are the rule, so that it is probable that the 750-watt lamps would mark the dividing line between flicker and non-flicker. Since all of the lamps employed in studio lighting service are of 1000 watts and above, I can assure you that there will be no possibility of flicker caused by the shutter getting into synchronism with the alternating current cyclic changes.
Mr Bauer: Some years ago Westinghouse went into the problem of sufficiently heavy filaments in incandescent lamps. As Mr. Farnham says, it happened frequently that the synchronism mentioned was noticeable on the screen as a decided flicker. The result of their investigation was that they brought out a transformer with a 20-ampere 20-volt light, which is equivalent to 400 watts. In an ordinary 400-watt incandescent lamp, the flicker would persist, but with the 20-volt 20-ampere lamp, the filament was sufficiently heavy to prevent this.
Mr Crabtree: I should like to mention that in the studio in Rochester for taking color motion pictures it is our practice to burn the lamps at under-voltage during arrangement of the set and at over-voltage only during actual exposure. This is done by means of rheostats.
Mr. Beggs: All the prize fights are photographed in the light of incandescent lamps. At Chicago they used 44 one thousand watt lamps in 44 reflectors. These burned at normal voltage and were of the ordinary type used for industrial lighting. Had they operated the lamps at over-voltage as in the Kodak studio, the total number of lamps could have been reduced about 30% using the same type of lamps and fixtures.
Recently, we received an order for lamps from a studio on the Coast asking for 2000- and 2500-watt lamps. The particular types described on the order are designed for high intensity spot lighting. They will give an average life of 50 hours each, and it will be our job to change the order to something more reasonable for studio lighting. Tomorrow we may have another order from another studio for lamps just as poorly suited for their work. The effect photographically is excellent, but the cost is excessive, and the chances are they will over-volt them. You should not over-volt a lamp designed for the extreme intensity of the 50-hour lamp, and yet I am quite sure that unless steps are taken by our representatives, that will be done. Steps can be taken now in advance, and Mr. Farnham and others could save a good deal of money in this way.
I think Mr. Farnham should tell the members about the heat of Mazda lamps, on which he has had direct experience.
Mr.Farnham: In my work in the various studios on the use of incandescent lamps, the question of heat from these lamps has never been raised. I have made inquiry on this point from the actors and other people employed on the sets, and the usual reply was that they had not noticed any particular difference. The incandescent lamp equipment does not require ballast resistances which dissipate a considerable quantity of heat and hence causes an increase of temperature in the vicinity of the set. The decrease in make-up required when incandescent lamps are employed unquestionably accounts for the greater comfort of the actors when working on sets lighted by incandescent lamps.
Mr. Ross: Do not the fast lenses now generally employed assist materially in reducing the illumination required?
Mr.Farnham: Yes. Heretofore, the standard lens has been the f/3.5, and the studios are now using f/2.3 or f/1.8 or 1.9, and one is experimenting with f/1.5 with very satisfactory results.

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