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APPENDIX D
COMPARISON OF EMULSION-SPEED VALUESa
ASA film numbers
Weston
General electric
H&D
American scheiner
European scheiner
Din
—
0.3
—
7.5
4
10
—
—
0.35
—
8.75
5
11
—
0.6
0.5
—
12.5
6
12
—
0.8
0.6
—
15
7
13
—
1.0
0.7
1
17.5
8
14
1/10
1.2
1.0
1.5
25
9
15
2/10
1.6
1.2
2
30
10
16
3/10
2.0
1.5
—
38
11
17
4/10
2.5
2.0
3
50
12
18
5/10
3
2.5
4
63
13
19
6/10
4
3
4.5
75
14
20
7/10
5
4
—
100
15
21
8/10
6
5
7.5
125
16
22
9/10
8
6
9
150
17
23
10/10
10
8
12
200
18
24
11/10
12
10
15
250
19
25
12/10
16
12
18
300
20
26
13/10
20
16
24
400
21
27
14/10
25
20
30
500
22
28
15/10
32
24
36
600
23
29
16/10
40
32
48
800
24
30
17/10
50
40
60
1,000
25
31
18/10
64
50
75
1,250
26
32
19/10
80
64
100
1,600
27
33
20/10
100
80
120
2,000
28
34
21/10
125
100
150
2,500
29
35
22/10
160
125
200
3,120
30
36
23/10
200
160
250
4,000
31
37
24/10
250
200
300
5,000
32
38
25/10
320
250
400
6,250
33
39
26/10
400
320
500
8,000
34
40
27/10
500
400
600
10,000
35
41
28/10
650
500
800
12,500
36
42
29/10
800
650
900
16,250
37
43
30/10
1000
800
1,000
20,000
38
44
31/10
a The table is only a rough guide to comparative speed values, since it is impossible to convert one kind of speed rating into another. (The different rating systems are based upon entirely different premises, methods, and test conditions.) The ASA rating is a manufacturer's test made at the time of manufacture; by definition it does not cover motion picture or color films. The Weston rating specifies purchase on the open market and 3 months' storage at 20 ± 5° C. and 55 ± 5 percent relative humidity prior to processing.
560