International projectionist (Jan-Dec 1938)

FIGURE 3 1.5 2.0 Ratio of Seating Length to thing else upon the necessity of satisfactorily viewing the picture. The factors involved are: (1) Picture detail: (a) Screen size in relation to view ing distance. (b) Screen brightness. (2) Obstruction of view. (3) Distortion of picture: (a) In projection. (b) In viewing. Figures 2-9 and Table I have been computed from the data provided by the returned survey charts. Figs. 2 and 7 will be especially helpful in studying the picture detail problem. Fig. 5 is intended for use in determining the area of the screen obstructed by the heads of spectators. Figs. 3 and 4 indicate the conditions controlling picture-image distortion due to viewing angles. Fig. 6 shows the projection angle, another factor affecting picture-image distortion. • Trend Toward Small Houses The survey indicates that seating capacities have steadily become smaller. Whereas 26 per cent of the theatres surveyed, erected before 1930, have capacities of 1,500 seats or over, only 10 per cent of the theatres erected after 1930 have capacities so great. Theatres of 2,000-seat capacity and over, erected after 1930, amount to only 5 per cent of the total. Future recommendations should show the disadvantages encountered when capacities of over 1,500 seats are contemplated. A point to be noted in the survey is that the characteristics of the theatres having capacities greater than 2,000 seats do not fall within the 50 per cent group, indicating that an important percentage of the seats in these large theatres are more or less subject to undesirable viewing conditions, and that best results in establishing standards of design will be attained if the seating capacities are assumed to be, say, 1,500 or less. This maximum applies to the usual rectangular ground plan. Somewhat greater capacities may be possible in a trapezium-shaped ground plan. Although the screen-image size is related to the maximum viewing distance, screen-image sizes in the thea 1.5 Sotting Width tres covered indicate a tendency toward sizes too small for the given viewing distances. This may be due to a general desire to avoid sufficient mag theatre proportions and dimensions, they do, however, reveal conditions that may be regarded as at least tolerable. For example, the conditions in theatres the proportions and dimensions of which fall within the 50 per cent group marked Seating area on the charts may, for immediate praccharacter tical purposes, be regarded as tolerable. istics Fig. 9 depicts these characteristics graphically. The figures shown should — — not be interpreted as representing any attempt on the part of the Committee, as yet, to fix maximum or minimum conditions: further analysis is required. Considered from the standpoint of visual aspects only, the ground plan of a motion picture theatre is controlled, FIGURE 4 i Relation of* S seating gio ■ width to • screen width \ ' 1 I "1 1 ' 613 Theaters \ ifT"hxJ ! ; J \ Alt 1 ii 1 //V ! 1 ! K i A 1 A^fl ' / \ A' • i \j^\ \ / V i i i T ^«j I / 1 ~\/P\i, w, , . , i i i ..... i . V i . . . . i , , vMrtf \Ar7?tfVr Ratio or Rear Seating width to Soraen width first, by the ability of the audience to see the details of the picture. This ability is determined by: (a) The illumination of the screen; (6) The brightness contrast of the projected image; (c) How much image detail is to be discernable to the spectator (the art of cinematography is here the guiding factor) ; nification to reveal film graininess and thereby assist in rendering seats closest to the screen undesirable. Fig. 8 shows that the average screen-image is 18.5 feet wide, 50 per cent of the theatres surveyed having screen-images ranging from 16 to 21 feet wide. Using the average screen width of 18.5 feet (Fig. 8) and assuming this width represents maximum desirable magnification of the 35 mm. film, approximately 800 seats can be arranged in a single tier. Should the maximum permissible magnification be assumed capable of producing eo an acceptable 25-foot screen image, a capacity of 1,100 ceats would be accomplished in *° a single tier. These capacities are arrived at by assuming, 8 temporarily, the averages in-| dicated in Figs. 3 and 4. If| a second or upper tier of seats S be employed in both the 800 % and 1.100-seat instances, these | capacities would be increased respectively to approximately 1,200 and 1,700 seats. These figures indicate the reason for assuming that 1,500 seats may be the advisable maximum capacity. While the data shown in the graphs do not determine, FIGURE 5 without further Study, ideal Location of screen above floor of auditorium 4 S » 7 DlatanM from floor to Bottom of Screen (Feat ami Inobew) JUNE 1938 17