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1945 Theatre Catalog, 4th Edition, Page 510 (484)

1945 Theatre Catalog, 4th Edition
1945 Theatre Catalog
1945 Theatre Catalog, 4th Edition, Page 510
Page 510

1945 Theatre Catalog, 4th Edition, Page 510

all the details in the picture upon the screen. If he sits at a greater distance from the screen, his eyes, however good, will not be capable of registering the finer details, and, as the distance is increased, the resolving power of the eyes becomes less and less. It is curious to note that increasing the screen illumination beyond the recommended brilliance does not increase the maximum viewing distance.

As is well known from personal experience, the screen picture gets blurred and seemingly out of focus as it is approached. While the eye will endeavor to adjust itself to these characteristics, as well as the irregularities of film motion, it cannot, for naturally, it cannot register a sharper image than it sees. The point at which these phenomena come in, and there eye becomes easily fatigued because of the large field of view, is approximately twoscreen widths away.

Thus, the seating area of a 16-min. theatre would have to be within a space represented by not more than four screen widths, with the nearest seats no closer than two screen widths.

Room Illumination

Motion pictures appear best when projected not in a totally black room, but when there is about 0.1 foot-candle of light, a level sufficiently high to bring the screen illumination into correct balance but not high enough to bring the surroundings inadvertently to noticeable and distracting attention. A 0.1 footcandle can popularly be that amount of light by which ordinary newspaper printing can be read only with difficulty when the paper is held 10 inches from the eyes.

Screen Illumination

Regardless of how nearly ideal may be other conditions for looking at motion pictures, if the screen illumination is not sufiiciently bright the picture cannot be comfortably viewed. If the picture is too bright, the contrast between the picture and the surrounding will be too great and the picture itself will appear too grainy, and eye strain and fatigue will result. If there is not enough light on the screen, the eyes will not be able to resolve the details of the picture, and again the eyes will suffer. The Society of Motion Picture Engineers has suggested a screen brightness of 10 foot-lamberts for auditoriums having the 0.1 foot-candle of general lighting.


For 16-min. motion pictures, there are two common types of screens, the white matte and the beaded.

The white matte screen, which, when new, reflects about 85 percent of the light falling upon it, is to be preferred because of its more uniform reflectivity and because it may be satisfactOrily looked at over wide viewing angles. The projector, for a screen of this type, in order to furnish the 10 foot-lamberts of screen brightness, must project upon it 12 foot-candles of light.

The beaded screen, while reflecting more light than the white matte screen, varies greatly in reference to the viewing angle. Because a beaded screen throws the greatest portion of the light back at the source, persons seated farther

off the line of projection would receive increasingly less light from the screen, and, accordingly, each one sees on the screen a different degree'of quality in the tones of the picture.

Maximum Length of Rows of Seats

When considering ,the maximum length of rows of seats, it should be remembered that the perspective changes with the various viewing angles. For example, when viewed from an angle of about 40 degrees, an oblong screen seems to be square, which means that the projected images appear about one-third thinner (but of the same height) than they actually are.

While the white matte screen can be used for wide viewing angles, this effect must be borne in mind when establishing the length of the row. Accordingly, the SMPE recommends that, for this screen, the maximum viewing angle be 30 degrees.

Seated at the end of a similar row, the view of a picture on a beaded screen gets the benefit of only one-quarter the

. brightness of a person seated in the cen ter of the row. Accordingly, for the beaded type of screen, the SMPE recommends the maximum viewing angle be established at 20 degrees.

Projection lumps

While there are some are lamps made for use with 16-mm. (Ampro Corporationls Amprosound Model AA uses a Strong Electric Corporation Junior High, 30-ampere, 28-volt carbon arc lamp), most of the available data are referable to incandescent projection lamps.

Assuming that the film is black-andwhite and the room has the recommended 0.1 foot-candle of general illumination, the power of the lamp depends to a large extent on screen size and the type of screen. For example, a 5-foot-wide white matte screen would require a 750watt bulb, while a beaded screen a 200watt bulb. Maximum screen width for a 1,000-watt bulb is about 8 feet, for the white matte screen, and 12 feet, for the beaded screen.

Proiection Distances

The length of throw is dependent on two main considerations: the focal length of the lens and the width of the desired screen picture.

For example, for pictures from 4 to 12 feet wide, a 1-inch projection lens would have to be moved back from a distance of 101/2 feet to 32 feet; a 2-inch lens, 16 feet to 48 feet; a 3-inch lens, from 32 feet to 96 feet; and a 4-inch lens, from 43 feet to 128 feet.

An Example Is Offered

Suppose that a theatre man has the equipment about which he would plan to operate a theatre, and he decides that a 9x12 foot screen and incandescent lighting are what he wants, what will he have?

First of all, it is obvious that the closest Seat to the screen is 24 feet away, with the most remote 72 feet removed. Now, assuming that, to play to the most people, he utilizes a white matte screen, he will find that the front row will be 28 feet wide and the back row 84 feet wide. From these figures, and assuming


that he can set up 20 rows of 24-inchwide chairs, spaced 32 inches back to back, the maximum seating capacity is about 360. V

In view of the fact that there are 10,000 35-mm. theatres presently operating in this country with seating capacities of less than 500, it is apparent that the present equipment could well be used by probably hundreds of existing theatres and by added hundreds of communities now devoid of motion picture entertainment.


At present under discussion in Hollywoodls technical centers-and in test by some manufacturers-is a new type of narrow-guage equipment, designed to utilize 20-mm. film.

This size has been set up as a possible compromise45-m1n. films for commercial theatres, 8- and 16-min. for amateur cinematographers and for non-theatrical (even though of entertainment) films, and the 20-mm. for commercial exhibition in situations where no theatres exist today.

While the set-up may be a good one, from the standpoint of denominating the three provinces of motion-picture use, it is felt in some quarters that the new equipment will have to be sold at a price so in excess of that presently charged for 16-mm. items that it would be economically inadvisable to use the new models in the situations for which the 16-mm. has been proposed.

A more likely avenue of approach to the problem of sturdy equipment, built to stand the gaff of commercial operatione which, it is admitted, may be bought for present machinery to doeis the creation of new pedestal models devised strictly from the standpoint of a permanent theatre job to be done. Of the 50,000 16-mm. sound projectors reported to have been purchased by the Armed Services, only a relatively few, probably because of the nature of their destinations and field use, were of what one might call the permanent, pedestal type, such as would be a prime requisite in a theatre model.

In the redesigning of the equipment to develop a theatre model, it might be possible to build in a 4,000-foot reel, and thus be able to put one hour and 52 minutes of show on a single reel. Such a reel would eliminate the need for a second projector and associated items of equipment, particularly since the rewinding necessary for the second show could be easily effected while the new audience was being seated.

But the most pressing need is, as should be obvious from the foregoing discussion of equipment, in projection lighting. While the bulb lighting may be all right for very small audiences, not much bigger than one might have a party in his home, theatre projection lighting will probably have to be by means of arcs. It has proved the most satisfactory, even in the smaller of the 35-mm. theatres, and the audiences of the 16-min. theatres deserve the highest quality that the equipment is able to deliver. Perhaps the answer to projection lighting, including that for 16-min. films, lies in the principle of uregimented light," recently described by the Western Union Telegraph Company.


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1945 Theatre Catalog, 4th Edition, Page 510