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MANAGERS AND PROJECTIONISTS 492c
a consideration of the fact that from a given point of observation the screen may appear of unequal brightness over its area. The danger of this inequality being serious increases rapidly as the value of the above mentioned ratio in reflecting
TABLE
No. 2
No.
0 deg.
5 deg.
10 deg.
20 deg.
30 deg.
40 deg.
50 deg
1
101)
1(30
100
99
98
98
97
2
61
61
60
59
58
57
56
3
80
79
78
77
76
74
70
4
113
109
106
94
83
80
79
5
82
82
82
81
81
81
81
6
132
125
115
88
66
50
37
7
163
150
134
93
61
43
31
8
414
361
295
153
71
32
17
9
436
385
319
161
73
34
20
10
427
380
300
163
73
36
18
11
80
79
77
74
69
68
68
12
301
281
240
140
76
43
23
13
274
255
223
132
73
43
24
14
271
244
205
132
77
45
26
15
220
200
173
115
68
40
24
16
357
315
264
149
73
38
21
17
76
75
74
73
72
71
69
18
338
305
252
129
75
42
22
19
151
139
125
89
60
43
30
20
78
77
77
76
75
74
73
21
291
273
204
83
55
48
47
22
217
205
167
89
63
55
51
23
357
328
280
145
66
36
21
24
228
215
194
140
83
54
35
25
80
79
78
76
74
72
69
26
86
86
85
83
82
80
76
27
82
80
79
76
72
69
66
28
72
71
70
68
66
64
63
29
450
417
324
150
67
35
22
30
348
280
2H0
105
58
31
18
31
319
281
231
130
69
37
21
32
436
347
269
127
60
43
20
33
84
84
78
76
76
75
75
34
280
242
150
67
48
39
37
35
294
284
242
148
71.5
34
19.6
36
409
394
342
186
82
37.4
19.6
37
309
298
268
163
77.2
38.6
21
powers increases. Assuming now that we adopt the value of 4
as the limiting value of the reflecting power ratio, it is possible from the figures in Tables 3, 4 and 5 to choose the best screen for any one of the cases considered. For instance, assuming that the maximum angle of observation is 20°, it will be noted that all values in the under 20° ratio column of Table 3 are less than 4. Therefore from the standpoint of distribution any one of the screens in Class A will be satisfactory for use