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492f HANDBOOK OF PROJECTION FOR
TABLE No.
4
CLASS
B
urface
30 deg.
30 deg.
40 deg.
50 deg.
No.
Ratio
R
Ratio R
Ratio
R
Ratio
R
6
1.06
115
1.26 105
1.38
96
1.51
87.6
7
1.21
135
1.36 120
1.52
107
1.72
95.0
14
2.05
213
3.50 186
6.02
162
10.4
143
15
1.91
177
3.24 155
4.78
136
9.16
120
19
1.70
126
2.52 113
3.51
101
5.03
91.0
22
2.44
170
3.44 148
3.94
133
4.25
121
24
1.63
194
2.74 172
4.22
152
6.52
136
Surface C is pebbled wall paper, P. 486 you will observe has essentially the same reflection power as kalsomine, but is not quite so perfect a diffusing surface.
Turning now to commercial screen surfaces, F and G, Pages 490, 491 are screen surfaces made and marketed by the same manufacturer.
Observe their enormously different characteristics. Surface E has a straight-in-front reflection power fully TWENTY TIMES AS GREAT as it has when viewed at a 50° angle. This means that the patron seated straight in front of such screen will see fully twenty times as brilliant a picture as will the one seated in the front side seat of a house wide enough to give that seat a 50° angle to the screen. The installation of such a surface in a wide theatre would be nothing less than a catastrophe. The surface is only adapted for use in a very narrow, long auditorium, and it is even questionable if it is adapted to theatre use at all, because even at a ten degree viewing angle the fade away is quite heavy, while at 20° the screen is not even half as brilliant as it was at straightin-front position.
TABLE No. 5 CLASS C Surface 20 deg. 30 deg. 40 deg. 50 deg.
No.
Ratio
R
Ratio
R
Ratio
R
Ratio
R
1
1.01
99.8
1.02
99.4
1.02
99.2
1.03
99.0
2
1.03
60.2
1.05
59.8
1.07
59.3
1.09
58.9
3
1.02
78.5
1.03
78.0
1.04
77.3
1.05
76.3
4
1.07
105
1.12
101
1.16
97.5
1.19
94.9
5
1.01
81.8
1.01
81.6
1.01
81.5
1.01
81.4
11
L08
77.5
1.16
75.8
1.18
74.5
1.18
73.7
17
1.04
74.5
1.06
74.0
1.07
73.5
1.10
72,9
20
1.03
77.0
1.04
76.6
1.05
76.2
1.07
75.7
25
1.05
78.2
1.08
77.4
1.11
76.5
1.16
75.4
26
1.04
85.0
1.05
84.0
1.07
83.0
1.13
82.0
27
1.08
79.2
1.14
77.8
1.19
76.3
1.24
75.0
28
1.06
70.2
1.09
69.4
1.12
68.5
1.14
67.7
33
1.10
83
1.10
82
1.12
80
1.12
79