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by no means be looked upon as an absolute rule. The size of the screen depends on what the job is, and in what surroundings. A small brilliant screen proportionate to the size of a decorative pylon flanking a wide aisle may be more effective than a vast screen in a still more vast hall crammed with interesting floor exhibits.
If a motion picture is to be the principal feature of an exhibit it must be shown on a size commensurate with its importance. If, on the other hand the picture is only incidental or contributory to a general exhibit, it should be fitted into proper scale.
The size of the image is determined by the projection distance available, and the focal length of the projector lens employed. As a guide, the following table of screen sizes used at the 1934 Fair in Chicago will be of interest.
SCREEN SIZE
PROJECTORS
Up to 12"
5
12" to 20"
20
20" to 30"
13
30" to 40"
32
40" to 50"
7
50" to 60"
. 6
60" to 96"
2
PEOPLE LIKE PUSHBUTTONS
The pushbutton is both a practical and interest-catching addition to the motion picture exhibit. Practical because it saves projector wear and economizes electricity it is also a never-failing curiosity attraction which gives the visitor chance to work something to his own satisfaction. Especially used with a continuous projector which automatically rewinds at the conclusion of the show.
The breakdown of types of screen material used gives us the following picture:
Beaded Screen Material for Direct Projection ... 17
Painted Wall Surface 15
Translucent Fabrics, for Rear Projection 34
Glass, for Rear Projection 11
The lenses used to obtain these pictures, were of the following focal length:
3"— 5; 21/2"— 3; 2"— 29; P/2"— 22; 1"— 13; 3/4"— 7; .64"— 6; (all of these are generally considered standard lens)
It should be noted that the 2" lens is the most efficient from the point of light passed, and that the 1 V2" lens is only slightly less fast.
The question of front projection or rear ("Translux") projection through a translucent screen material is also of interest:
Front projection 32
Rear projection 56
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EXHIBIT showmanship differs according to the product and the type of audience. The rules developed from experiences at Chicago's Century of Progress and disclosed in the survey above may easily be applied to the individual problem. Readers are invited to^ address their problems, with a sketch of the contemplated exhibit area or other space in which projection may be used if possible, to the offices of Business Screen. Competent, experienced technical assistance will be freely given without the slightest obligation. In subsequent numbers of the magazine many additional applications of exhibit projection will be illustrated, including an article on the remarkable Museum of Science and Industry in Rockefeller Center, New York.
Editorial credit is due to the technical staff of Bell & Howell and to Burton Holmes Films of Chicago for much of the valuable information contained in the survey presented this month.
HOW TO USE FILMS IN EXHIBITS
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