Loyd A. Jones and H. R. Condit, "Sunlight and Skylight as Determinants of Photographic Exposure.a I. Luminous Density as Determined by Solar Altitude and Atmospheric Conditions," J. Opt. Soc. Am. 38, 123-178 (1948)
Loyd A. Jones and H. R. Condit, "Errata: Sunlight and Skylight as Determinants of Photographic Exposure. I. Luminous Density as Determined by Solar Altitude and Atmospheric Conditions," J. Opt. Soc. Am. 39, 135-135 (1949) https://opg.optica.org/josa/abstract.cfm?uri=josa-39-2-135
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K=Ratio of photometric to the corresponding radiometric term, thus K=L6/R6=Luminous efficiency (lumens/watt) of the radiant energy involved
Photometric (Psychophysical)
L1
Luminator (source of luminous energy)
L2
Lumination (process)
L4
Luminous energy
Q
lumerg
talbot
L5
Luminous density
q
lumerg/cm3
talbot/m3
L6
Luminous flux
F
lumerg/sec
lumen
L7
Luminous emittance
L
lumerg/sec/cm2
lumen/m2
L8
Luminous intensity
I
lumerg/sec/ω
lumen/ω (candle)
L9
Luminance
B
lumerg/sec/ω/cm2
lumen/ω/m2 (candle/m2)
L10
Illuminance
E
lumerg/sec/cm2
lumen/m2 (lux)
The nomenclature given in this table and used in this communication differs in many details from the nomenclature recommended by the Illuminating Engineering Society and approved by the American Standards Association. These modifications of the standard nomenclature were proposed by the Colorimetry Committee of the Optical Society of America (in 1937 and 144) as somewhat simpler and more systematic, with hope that they might be considered in any revisions of the standard nomenclature. The letter symbols shown in the table are identical with those adopted by the American Standards Association for the corresponding concepts. The symbol ω denotes a unit solid angle, the solid angle subtended by one square meter of the surface of a sphere having the radius of one meter.
Table II
Luminance of the clear sky, winter and summer values.
Solar altitude
Azimuth from sun
Altitude for luminance values
2°
15°
30°
45°
60°
75°
90°
Clear Sky, Winter
0°
0°
319
242
109
60.5
36.3
29.0
25.2
45
111
120
71.3
49.9
34.3
29.0
90
61.2
69.6
52.4
37.0
30.2
27.7
135
75.3
86.4
60.7
39.8
29.5
26.0
180
96.5
106
69.0
44.6
31.5
27.2
20°
0°
6140
—
2550
1110
590
371
261
45
2330
1450
981
671
457
331
90
1030
679
441
339
287
277
135
1020
611
371
264
227
230
180
1140
666
371
258
211
206
40°
0°
4190
3450
4780
—
1380
774
506
45
2310
1750
1400
1120
891
688
90
1330
840
567
506
450
481
135
1270
673
415
344
334
380
180
1400
729
410
304
293
349
Clear Sky, Summer
20°
0°
7850
—
4040
1510
870
521
372
45
2870
2190
1450
1020
722
487
90
1270
1050
662
502
398
424
135
923
692
458
309
268
305
180
1060
792
443
316
275
283
40°
0°
5480
4620
6290
—
2050
1180
746
45
3100
2330
2010
1830
1400
1060
90
1590
1050
843
724
739
776
135
1300
843
552
448
463
552
180
1370
828
507
403
395
507
60°
0°
3180
2660
2820
3840
—
2520
1530
45
2660
2340
1990
2340
2560
2160
90
1770
1350
1100
1130
1350
1510
135
1450
933
719
765
887
1150
180
1530
979
719
765
826
1100
70°
0°
3100
2760
2420
3420
7060
—
2140
45
2680
1930
1900
2290
2850
3270
90
1650
1390
1200
1160
1330
1900
135
1330
899
792
813
942
1410
180
1240
835
663
663
877
1310
Table III
Luminance of the clear sky, average of winter and summer values.
Solar altitude
Azimuth from sun
Altitude for luminance values
2°
15°
30°
45°
60°
75°
90°
0°
0°
364
294
141
71.4
44.8
34.8
30.5
45
124
151
88.4
62.9
44.2
35.8
90
68.2
88.7
65.5
45.9
36.1
35.0
135
71.7
92.0
68.7
43.2
32.2
30.3
180
93.1
116
75.6
49.5
36.2
32.2
20°
0°
7000
—
3300
1310
730
446
316
45
2600
1820
1220
846
590
409
90
1150
864
552
420
342
350
135
972
652
414
286
248
268
180
1100
729
407
287
243
244
40°
0°
4840
4040
5540
—
1720
977
626
45
2700
2040
1700
1480
1150
874
90
1460
945
705
615
594
628
135
1280
758
484
396
398
466
180
1380
778
458
354
344
428
60°
0°
2810
2320
2480
3290
—
2090
1280
45
2320
2050
1690
1890
2090
1780
90
1620
1220
920
960
1090
1220
135
1430
839
630
676
763
971
180
1550
920
650
671
719
928
70°
0°
2740
2410
2130
2930
5910
—
1790
45
2340
1690
1610
1850
2330
2700
90
1510
1250
1000
985
1070
1540
135
1310
808
694
719
810
1190
180
1250
785
600
581
764
1110
Table IV
Illuminance due to direct sunlight, skylight, and total on horizontal and vertical planes.
Solar altitude h
Air mass m
Direct sunlight
Skylight
Total
Ihd
Ipd
Ihs
Ips
Iht
Ipt
ft.-c
ft.-c
ft.-c
3
15.36
19.6
374
256
587
277
961
5
10.39
100
1150
325
746
425
1900
7
7.77
252
2050
395
848
647
2900
10
5.60
590
3350
491
953
1080
4300
15
3.82
1310
3910
629
1070
1940
5980
20
2.90
2130
5860
750
1140
2880
7000
25
2.36
2980
6390
856
1180
3840
7570
30
2.00
3820
6620
945
1210
4760
7830
35
1.74
4650
6640
1020
1220
5670
7860
40
1.55
5440
6490
1090
1220
6530
7710
45
1.41
6170
6170
1160
1220
7330
7390
50
1.30
6850
5750
1210
1200
8060
6950
55
1.22
7450
5220
1270
1180
8720
6400
60
1.15
8000
4620
1310
1150
9310
5770
65
1.10
8470
3950
1350
1090
9820
5040
70
1.06
8860
3230
1390
1020
10250
4250
75
1.04
9160
2450
1420
930
10580
3380
80
1.02
9380
1650
1440
834
10820
2480
85
1.01
9510
833
1460
728
10970
1560
90
1.00
9570
0
1480
615
11050
615
Table V
Data (from Fig. 16) illustrating the consequences of introducing a variable flare factor into Eq. (20a).
Negative material
Negative
FF
Gx min
Kx
DSn
Gn min
Kn
1
0.68
0.20
0.29
1.42
0.68
0.20
0.29
2
0.66
0.20
0.30
1.18
0.55
0.10
0.18
4
0.61
0.20
0.33
0.92
0.44
0.05
0.11
8
0.56
0.20
0.36
0.66
0.31
0.025
0.08
Table VI
Data (from Fig. 17) illustrating the consequences of using a fixed flare factor (FF=4.0) when photographing scenes in which the flare factor is variable.
Negative material
Negative
FF
Gx min
Kx
DSn
Gn min
Kn
Kn′
1
0.46
0.00
0.00
0.96
0.46
0.00
0.00
0.15
2
0.53
0.06
0.11
0.95
0.45
0.03
0.07
0.17
4
0.61
0.20
0.33
0.92
0.44
0.05
0.11
0.18
8
0.67
0.38
0.57
0.83
0.40
0.05
0.12
0.20
Table VII
Values of illuminance (foot candles) on the normal plane and of luminous density (lumerg/cu. ft.) attributable to direct sunlight, skylight, and the total.
Direct sunlight
Skylight
Total
Solar altitude h
Air mass m
Illuminance Ind ft.-c
Luminous density Vd ft.-lg
Illuminance Ins ft.-c
Luminous density Vs ft.-lg
Illuminance Int ft.-c
Luminous density Vt ft.-lg
3
15.36
375
3.82
605
5.46
980
9.28
5
10.39
1150
11.7
767
7.96
1920
19.7
7
7.77
2070
21.1
873
10.4
2940
31.5
10
5.60
3400
34.7
987
13.7
4390
48.4
15
3.82
5080
51.8
1120
18.4
6200
70.2
20
2.90
6240
63.6
1220
21.7
7460
85.3
25
2.36
7050
71.9
1280
24.0
8330
95.9
30
2.00
7640
77.9
1320
25.5
8960
103
35
1.74
8110
82.7
1350
26.7
9460
109
40
1.55
8470
86.4
1370
27.5
9840
114
45
1.41
8720
88.9
1390
28.3
10110
117
50
1.30
8940
91.2
1400
28.8
10340
120
55
1.22
9100
92.8
1420
29.2
10520
122
60
1.15
9240
94.2
1430
29.5
10670
124
65
1.10
9350
95.4
1440
29.7
10790
125
70
1.06
9430
96.2
1450
29.9
10880
126
75
1.04
9480
96.7
1450
30.0
10930
127
80
1.02
9520
97.1
1460
30.2
10980
127
85
1.01
9550
97.4
1470
30.3
11020
128
90
1.00
9570
97.6
1480
30.4
11050
128
Table VIII
Specification of the latitude bands for which the variations of solar altitude with hours of the day and month are computed.
Latitude
Latitude zone
0°
5°N to 5°S
10
5 to 15°N or S
20
15 to 25°N or S
30
25 to 35°N or S
40
35 to 45°N or S
50
45 to 55°N or S
60
55 to 65°N or S
70
65 to 75°N or S
80
75 to 85°N or S
90
85 to 90°N or S
Table IX
Solar altitude at various hours and months at latitude 40°N.
Hours before or after noon, local solar time
0
1
2
3
4
5
6
7
June
73.4
69.1
59.8
48.8
37.4
25.9
14.8
4.2
July
May
70.1
66.3
57.6
46.8
35.5
24.0
12.8
Aug.
Apr.
61.3
58.4
50.9
41.1
30.1
18.7
7.2
Sept.
Mar.
50.0
47.7
41.6
32.8
22.5
11.4
Oct.
Feb.
38.7
36.8
31.6
23.9
14.5
3.9
Nov.
Jan.
29.9
28.3
23.7
16.7
8.0
Dec.
26.6
25.1
20.7
14.0
5.5
Table X
Luminous densities at latitude 40°N.
Hours before or after noon, local solar time
0
1
2
3
4
5
6
7
Luminous Density, Foot-Lumergs
June
127
126
124
119
112
98
70
16
July
May
126
125
123
118
110
94
62
Aug.
Apr.
124
123
120
115
104
82
33
Sept.
March
120
119
115
107
91
55
Oct.
Feb.
113
111
106
94
69
14
Nov.
Jan.
103
101
94
77
38
Dec.
99
96
87
67
23
Luminous Density Ratios, Rv
June
1.01
1.02
1.03
1.08
1.14
1.31
1.83
8.0
July
May
1.02
1.02
1.04
1.09
1.16
1.36
2.06
Aug.
Apr.
1.03
1.04
1.07
1.11
1.23
1.56
3.88
Sept.
March
1.07
1.08
1.11
1.20
1.41
2.33
Oct.
Feb.
1.13
1.15
1.21
1.36
1.86
9.15
Nov.
Jan.
1.24
1.27
1.36
1.68
3.27
Dec.
1.29
1.33
1.47
1.91
5.57
Light Indices, Lv
June
0
0
0
0
1
1
3
9
July
May
0
0
0
0
1
1
3
Aug.
Apr.
0
0
0
0
1
2
6
Sept.
March
0
0
0
1
1
4
Oct.
Feb.
1
1
1
1
3
10
Nov.
Jan.
I
1
1
2
5
Dec.
1
1
2
3
7
Table XI
Consecutive whole numbers, column 3, which represent all values of light index, Lv, between the limits as shown in the first column and the corresponding values of luminous density, Column 4.
Luminous density ratio, Rv
Light index Lv
Luminous density Ft.-lg
Limits
Midpoint
1.00– 1.12
1.00
0
128
1.13– 1.41
1.26
1
102
1.42– 1.78
1.59
2
80.5
1.79– 2.24
2.00
3
64.0
2.25– 2.83
2.52
4
50.8
2.84– 3.56
3.18
5
40.3
3.57– 4.49
4.00
6
32.0
4.50– 5.66
5.04
7
25.4
5.67– 7.13
6.35
8
20.2
7.14– 8.98
8.00
9
16.0
8.99–11.3
10.0
10
12.8
Table XII
Light indices for various latitudes, local solar time.
Latitude 0°
11
10
9
8
7
6:30 A.M.
North
Noon
1
2
3
4
5
5:30 P.M.
South
June
0
0
0
0
1
3
6
Dec.
July
Jan.
May
0
0
0
0
1
3
6
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
3
6
Oct.
Sept.
Mar.
Mar.
0
0
0
0
1
3
6
Sept.
Oct.
Apr.
Feb.
0
0
0
0
1
3
6
Aug.
Nov.
May
Jan.
0
0
0
0
1
3
6
July
Dec.
0
0
0
0
1
3
6
June
Latitude 10°
11
10
9
8
7
6 A.M.
North
Noon
1
2
3
4
5
6 P.M.
South
June
0
0
0
0
1
2
9
Dec.
July
Jan.
May
0
0
0
0
1
2
10
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
Oct.
Sept.
Mar.
Mar.
0
0
0
0
1
3
Sept.
Oct.
Apr.
Feb.
0
0
0
0
1
3
Aug.
Nov.
May
Jan.
0
0
0
1
1
4
July
Dec.
0
0
0
1
1
4
June
Latitude 20°
11
10
9
8
7
6 A.M.
North
Noon
1
2
3
4
5
6 P.M.
South
June
0
0
0
0
1
2
5
Dec.
July
Jan.
May
0
0
0
0
1
2
6
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
10
Oct.
Sept.
Mar.
Mar.
0
0
0
0
1
3
Sept.
Oct.
Apr.
Feb.
0
0
0
1
1
4
Aug.
Nov.
May
Jan.
0
0
0
1
2
7
July
Dec.
0
0
1
1
2
8
June
Latitude 30°
11
10
9
8
7
6 A.M.
North
Noon
1
2
3
4
5
6 P.M.
South
June
0
0
0
0
1
1
4
Dec.
July
Jan.
May
0
0
0
0
1
1
4
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
7
Oct.
Sept.
Mar.
Mar.
0
0
0
1
1
3
Sept.
Oct.
Apr.
Feb.
0
0
0
1
2
6
Aug.
Nov.
May
Jan.
0
1
1
1
3
July
Dec.
1
1
1
2
4
June
Latitude 40°
11
10
9
8
7
6
5 A.M.
North
Noon
1
2
3
4
5
6
7 P.M.
South
June
0
0
0
0
1
1
3
9
Dec.
July
Jan.
May
0
0
0
0
1
1
3
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
6
Oct.
Sept.
Mar.
Mar.
0
0
0
1
1
4
Sept.
Oct.
Apr.
Feb.
1
1
1
1
3
10
Aug.
Nov.
May
Jan.
1
1
1
2
5
July
Dec.
1
1
2
3
7
June
Latitude 50°
11
10
9
8
7
6
5 A.M.
North
Noon
1
2
3
4
5
6
7 P.M.
South
June
0
0
0
0
1
1
2
5
Dec.
July
Jan.
May
0
0
0
0
1
1
2
7
Nov.
Aug.
Feb.
Apr.
0
0
0
1
1
2
5
Oct.
Sept.
Mar.
Mar.
0
1
1
1
2
4
Sept.
Oct.
Apr.
Feb.
1
1
1
2
4
Aug.
Nov.
May
Jan.
2
2
3
4
July
Dec.
2
2
4
6
June
Latitude 60°
11
10
9
8
7
6
5
4 A.M.
North
Noon
1
2
3
4
5
6
7
8 P.M.
South
June
0
0
0
0
1
1
2
3
6
Dec.
July
Jan.
May
0
0
0
1
1
1
2
4
10
Nov.
Aug.
Feb.
Apr.
0
0
1
1
1
2
4
Oct.
Sept.
Mar.
Mar.
1
1
1
2
3
6
Sept.
Oct.
Apr.
Feb.
2
2
3
4
9
Aug.
Nov.
May
Jan.
4
5
7
July
Dec.
6
7
June
Latitude 70°
11
10
9
8
7
6
5
4
3
2
1 A.M.
North
Noon
1
2
3
4
5
6
7
8
9
10
11 P.M.
Midnight
South
June
0
0
0
1
1
1
2
2
3
5
7
9
10
Dec.
July
Jan.
May
0
1
1
1
1
1
2
3
5
7
Nov.
Aug.
Feb.
Apr.
1
1
1
1
2
2
4
7
Oct.
Sept.
Mar.
Mar.
2
2
2
3
4
8
Sept.
Oct.
Apr.
Feb.
5
5
7
Aug.
Latitude 80°
11
10
9
8
7
6
5
4
3
2
1 A.M.
North
Noon
1
2
3
4
5
6
7
8
9
10
11 P.M.
Midnight
South
June
1
1
1
1
1
1
1
2
2
2
3
3
3
Dec.
July
Jan.
May
1
1
1
1
1
1
2
2
3
3
4
4
4
Nov.
Aug.
Feb.
Apr.
2
2
2
2
2
3
4
5
7
9
Oct.
Sept.
Mar.
Mar.
4
4
5
6
8
Sept.
Latitude 90°
North
All hours
South
June
1
Dec.
July
Jan.
May
2
Nov.
Aug.
Feb.
Apr.
4
Oct.
Table XIII
Numerical values which characterize the atmospheric conditions indicated in Column 1.
Atmospheric conditions
Sun B
Sky illuminance foot-lamberts
Luminance density foot-lumergs
Rel. camera exposure Ra
Atmospheric index A
Max.
Avg.
Min.
Vd
Vs
Vt
Perfectly clear
500×106
(3)
1,400
740
(2)
400
110
15
125
—
—
Clear
450×106
(1)
6,000
1500
(4)
650
97.6
30.4
128
1.0
0
Light haze
14×106
(1)
100,000
4300
(4)
1800
3.1
87.9
91
1.4
1.5
Medium haze
450×103
(1)
25,000
3150
1500
0.097
63.9
64
2.0
3
Heavy haze
15×103
(1)
8,000
2150
1200
0.003
44
44
3.2
5
Light cloud
0
(1)
4,000
1750
1000
0
36
36
Medium cloud
0
(2)
2,500
1300
(3)
650
0
26
26
5
7
Heavy cloud
0
(2)
1,200
640
(3)
400
0
13
13
10
10
Dense cloud
0
(2)
400
200
(3)
150
0
4
4
32
15
near sun
near zenith
near horizon
approximately 90° from sun, measured through zenith.
Table XIV
Atmospheric index, A, for various atmospheric conditions.
Atmospheric condition
Vt
Ra
A
Clear
128
1.0
0
Light haze
91
1.4
15
Medium haze
64
2.0
3
Heavy haze
44
3.2
5
Light cloud
36
Medium cloud
26
5
7
Heavy cloud
13
10
10
Dense cloud
4
32
15
Tables (14)
Table I
Radiometric and photometric terminology.
Radiometric (Physical)
R1
Radiator (source of radiant energy)
R2
Radiation (process)
Name
Symbol
c.g.s.
m.k.s.
R4
Radiant energy
U
erg
joule
R5
Radiant density
u
erg/cm3
joule/m3
R6
Radiant flux
P
erg/sec
watt
R7
Radiant emittance
W
erg/sec/cm2
watt/m2
R8
Radiant intensity
J
erg/sec/ω
watt/ω
R9
Radiance
N
erg/sec/ω/cm2
watt/ω/m2
R10
Irradiance
H
erg/sec/cm2
watt/m2
K=Ratio of photometric to the corresponding radiometric term, thus K=L6/R6=Luminous efficiency (lumens/watt) of the radiant energy involved
Photometric (Psychophysical)
L1
Luminator (source of luminous energy)
L2
Lumination (process)
L4
Luminous energy
Q
lumerg
talbot
L5
Luminous density
q
lumerg/cm3
talbot/m3
L6
Luminous flux
F
lumerg/sec
lumen
L7
Luminous emittance
L
lumerg/sec/cm2
lumen/m2
L8
Luminous intensity
I
lumerg/sec/ω
lumen/ω (candle)
L9
Luminance
B
lumerg/sec/ω/cm2
lumen/ω/m2 (candle/m2)
L10
Illuminance
E
lumerg/sec/cm2
lumen/m2 (lux)
The nomenclature given in this table and used in this communication differs in many details from the nomenclature recommended by the Illuminating Engineering Society and approved by the American Standards Association. These modifications of the standard nomenclature were proposed by the Colorimetry Committee of the Optical Society of America (in 1937 and 144) as somewhat simpler and more systematic, with hope that they might be considered in any revisions of the standard nomenclature. The letter symbols shown in the table are identical with those adopted by the American Standards Association for the corresponding concepts. The symbol ω denotes a unit solid angle, the solid angle subtended by one square meter of the surface of a sphere having the radius of one meter.
Table II
Luminance of the clear sky, winter and summer values.
Solar altitude
Azimuth from sun
Altitude for luminance values
2°
15°
30°
45°
60°
75°
90°
Clear Sky, Winter
0°
0°
319
242
109
60.5
36.3
29.0
25.2
45
111
120
71.3
49.9
34.3
29.0
90
61.2
69.6
52.4
37.0
30.2
27.7
135
75.3
86.4
60.7
39.8
29.5
26.0
180
96.5
106
69.0
44.6
31.5
27.2
20°
0°
6140
—
2550
1110
590
371
261
45
2330
1450
981
671
457
331
90
1030
679
441
339
287
277
135
1020
611
371
264
227
230
180
1140
666
371
258
211
206
40°
0°
4190
3450
4780
—
1380
774
506
45
2310
1750
1400
1120
891
688
90
1330
840
567
506
450
481
135
1270
673
415
344
334
380
180
1400
729
410
304
293
349
Clear Sky, Summer
20°
0°
7850
—
4040
1510
870
521
372
45
2870
2190
1450
1020
722
487
90
1270
1050
662
502
398
424
135
923
692
458
309
268
305
180
1060
792
443
316
275
283
40°
0°
5480
4620
6290
—
2050
1180
746
45
3100
2330
2010
1830
1400
1060
90
1590
1050
843
724
739
776
135
1300
843
552
448
463
552
180
1370
828
507
403
395
507
60°
0°
3180
2660
2820
3840
—
2520
1530
45
2660
2340
1990
2340
2560
2160
90
1770
1350
1100
1130
1350
1510
135
1450
933
719
765
887
1150
180
1530
979
719
765
826
1100
70°
0°
3100
2760
2420
3420
7060
—
2140
45
2680
1930
1900
2290
2850
3270
90
1650
1390
1200
1160
1330
1900
135
1330
899
792
813
942
1410
180
1240
835
663
663
877
1310
Table III
Luminance of the clear sky, average of winter and summer values.
Solar altitude
Azimuth from sun
Altitude for luminance values
2°
15°
30°
45°
60°
75°
90°
0°
0°
364
294
141
71.4
44.8
34.8
30.5
45
124
151
88.4
62.9
44.2
35.8
90
68.2
88.7
65.5
45.9
36.1
35.0
135
71.7
92.0
68.7
43.2
32.2
30.3
180
93.1
116
75.6
49.5
36.2
32.2
20°
0°
7000
—
3300
1310
730
446
316
45
2600
1820
1220
846
590
409
90
1150
864
552
420
342
350
135
972
652
414
286
248
268
180
1100
729
407
287
243
244
40°
0°
4840
4040
5540
—
1720
977
626
45
2700
2040
1700
1480
1150
874
90
1460
945
705
615
594
628
135
1280
758
484
396
398
466
180
1380
778
458
354
344
428
60°
0°
2810
2320
2480
3290
—
2090
1280
45
2320
2050
1690
1890
2090
1780
90
1620
1220
920
960
1090
1220
135
1430
839
630
676
763
971
180
1550
920
650
671
719
928
70°
0°
2740
2410
2130
2930
5910
—
1790
45
2340
1690
1610
1850
2330
2700
90
1510
1250
1000
985
1070
1540
135
1310
808
694
719
810
1190
180
1250
785
600
581
764
1110
Table IV
Illuminance due to direct sunlight, skylight, and total on horizontal and vertical planes.
Solar altitude h
Air mass m
Direct sunlight
Skylight
Total
Ihd
Ipd
Ihs
Ips
Iht
Ipt
ft.-c
ft.-c
ft.-c
3
15.36
19.6
374
256
587
277
961
5
10.39
100
1150
325
746
425
1900
7
7.77
252
2050
395
848
647
2900
10
5.60
590
3350
491
953
1080
4300
15
3.82
1310
3910
629
1070
1940
5980
20
2.90
2130
5860
750
1140
2880
7000
25
2.36
2980
6390
856
1180
3840
7570
30
2.00
3820
6620
945
1210
4760
7830
35
1.74
4650
6640
1020
1220
5670
7860
40
1.55
5440
6490
1090
1220
6530
7710
45
1.41
6170
6170
1160
1220
7330
7390
50
1.30
6850
5750
1210
1200
8060
6950
55
1.22
7450
5220
1270
1180
8720
6400
60
1.15
8000
4620
1310
1150
9310
5770
65
1.10
8470
3950
1350
1090
9820
5040
70
1.06
8860
3230
1390
1020
10250
4250
75
1.04
9160
2450
1420
930
10580
3380
80
1.02
9380
1650
1440
834
10820
2480
85
1.01
9510
833
1460
728
10970
1560
90
1.00
9570
0
1480
615
11050
615
Table V
Data (from Fig. 16) illustrating the consequences of introducing a variable flare factor into Eq. (20a).
Negative material
Negative
FF
Gx min
Kx
DSn
Gn min
Kn
1
0.68
0.20
0.29
1.42
0.68
0.20
0.29
2
0.66
0.20
0.30
1.18
0.55
0.10
0.18
4
0.61
0.20
0.33
0.92
0.44
0.05
0.11
8
0.56
0.20
0.36
0.66
0.31
0.025
0.08
Table VI
Data (from Fig. 17) illustrating the consequences of using a fixed flare factor (FF=4.0) when photographing scenes in which the flare factor is variable.
Negative material
Negative
FF
Gx min
Kx
DSn
Gn min
Kn
Kn′
1
0.46
0.00
0.00
0.96
0.46
0.00
0.00
0.15
2
0.53
0.06
0.11
0.95
0.45
0.03
0.07
0.17
4
0.61
0.20
0.33
0.92
0.44
0.05
0.11
0.18
8
0.67
0.38
0.57
0.83
0.40
0.05
0.12
0.20
Table VII
Values of illuminance (foot candles) on the normal plane and of luminous density (lumerg/cu. ft.) attributable to direct sunlight, skylight, and the total.
Direct sunlight
Skylight
Total
Solar altitude h
Air mass m
Illuminance Ind ft.-c
Luminous density Vd ft.-lg
Illuminance Ins ft.-c
Luminous density Vs ft.-lg
Illuminance Int ft.-c
Luminous density Vt ft.-lg
3
15.36
375
3.82
605
5.46
980
9.28
5
10.39
1150
11.7
767
7.96
1920
19.7
7
7.77
2070
21.1
873
10.4
2940
31.5
10
5.60
3400
34.7
987
13.7
4390
48.4
15
3.82
5080
51.8
1120
18.4
6200
70.2
20
2.90
6240
63.6
1220
21.7
7460
85.3
25
2.36
7050
71.9
1280
24.0
8330
95.9
30
2.00
7640
77.9
1320
25.5
8960
103
35
1.74
8110
82.7
1350
26.7
9460
109
40
1.55
8470
86.4
1370
27.5
9840
114
45
1.41
8720
88.9
1390
28.3
10110
117
50
1.30
8940
91.2
1400
28.8
10340
120
55
1.22
9100
92.8
1420
29.2
10520
122
60
1.15
9240
94.2
1430
29.5
10670
124
65
1.10
9350
95.4
1440
29.7
10790
125
70
1.06
9430
96.2
1450
29.9
10880
126
75
1.04
9480
96.7
1450
30.0
10930
127
80
1.02
9520
97.1
1460
30.2
10980
127
85
1.01
9550
97.4
1470
30.3
11020
128
90
1.00
9570
97.6
1480
30.4
11050
128
Table VIII
Specification of the latitude bands for which the variations of solar altitude with hours of the day and month are computed.
Latitude
Latitude zone
0°
5°N to 5°S
10
5 to 15°N or S
20
15 to 25°N or S
30
25 to 35°N or S
40
35 to 45°N or S
50
45 to 55°N or S
60
55 to 65°N or S
70
65 to 75°N or S
80
75 to 85°N or S
90
85 to 90°N or S
Table IX
Solar altitude at various hours and months at latitude 40°N.
Hours before or after noon, local solar time
0
1
2
3
4
5
6
7
June
73.4
69.1
59.8
48.8
37.4
25.9
14.8
4.2
July
May
70.1
66.3
57.6
46.8
35.5
24.0
12.8
Aug.
Apr.
61.3
58.4
50.9
41.1
30.1
18.7
7.2
Sept.
Mar.
50.0
47.7
41.6
32.8
22.5
11.4
Oct.
Feb.
38.7
36.8
31.6
23.9
14.5
3.9
Nov.
Jan.
29.9
28.3
23.7
16.7
8.0
Dec.
26.6
25.1
20.7
14.0
5.5
Table X
Luminous densities at latitude 40°N.
Hours before or after noon, local solar time
0
1
2
3
4
5
6
7
Luminous Density, Foot-Lumergs
June
127
126
124
119
112
98
70
16
July
May
126
125
123
118
110
94
62
Aug.
Apr.
124
123
120
115
104
82
33
Sept.
March
120
119
115
107
91
55
Oct.
Feb.
113
111
106
94
69
14
Nov.
Jan.
103
101
94
77
38
Dec.
99
96
87
67
23
Luminous Density Ratios, Rv
June
1.01
1.02
1.03
1.08
1.14
1.31
1.83
8.0
July
May
1.02
1.02
1.04
1.09
1.16
1.36
2.06
Aug.
Apr.
1.03
1.04
1.07
1.11
1.23
1.56
3.88
Sept.
March
1.07
1.08
1.11
1.20
1.41
2.33
Oct.
Feb.
1.13
1.15
1.21
1.36
1.86
9.15
Nov.
Jan.
1.24
1.27
1.36
1.68
3.27
Dec.
1.29
1.33
1.47
1.91
5.57
Light Indices, Lv
June
0
0
0
0
1
1
3
9
July
May
0
0
0
0
1
1
3
Aug.
Apr.
0
0
0
0
1
2
6
Sept.
March
0
0
0
1
1
4
Oct.
Feb.
1
1
1
1
3
10
Nov.
Jan.
I
1
1
2
5
Dec.
1
1
2
3
7
Table XI
Consecutive whole numbers, column 3, which represent all values of light index, Lv, between the limits as shown in the first column and the corresponding values of luminous density, Column 4.
Luminous density ratio, Rv
Light index Lv
Luminous density Ft.-lg
Limits
Midpoint
1.00– 1.12
1.00
0
128
1.13– 1.41
1.26
1
102
1.42– 1.78
1.59
2
80.5
1.79– 2.24
2.00
3
64.0
2.25– 2.83
2.52
4
50.8
2.84– 3.56
3.18
5
40.3
3.57– 4.49
4.00
6
32.0
4.50– 5.66
5.04
7
25.4
5.67– 7.13
6.35
8
20.2
7.14– 8.98
8.00
9
16.0
8.99–11.3
10.0
10
12.8
Table XII
Light indices for various latitudes, local solar time.
Latitude 0°
11
10
9
8
7
6:30 A.M.
North
Noon
1
2
3
4
5
5:30 P.M.
South
June
0
0
0
0
1
3
6
Dec.
July
Jan.
May
0
0
0
0
1
3
6
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
3
6
Oct.
Sept.
Mar.
Mar.
0
0
0
0
1
3
6
Sept.
Oct.
Apr.
Feb.
0
0
0
0
1
3
6
Aug.
Nov.
May
Jan.
0
0
0
0
1
3
6
July
Dec.
0
0
0
0
1
3
6
June
Latitude 10°
11
10
9
8
7
6 A.M.
North
Noon
1
2
3
4
5
6 P.M.
South
June
0
0
0
0
1
2
9
Dec.
July
Jan.
May
0
0
0
0
1
2
10
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
Oct.
Sept.
Mar.
Mar.
0
0
0
0
1
3
Sept.
Oct.
Apr.
Feb.
0
0
0
0
1
3
Aug.
Nov.
May
Jan.
0
0
0
1
1
4
July
Dec.
0
0
0
1
1
4
June
Latitude 20°
11
10
9
8
7
6 A.M.
North
Noon
1
2
3
4
5
6 P.M.
South
June
0
0
0
0
1
2
5
Dec.
July
Jan.
May
0
0
0
0
1
2
6
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
10
Oct.
Sept.
Mar.
Mar.
0
0
0
0
1
3
Sept.
Oct.
Apr.
Feb.
0
0
0
1
1
4
Aug.
Nov.
May
Jan.
0
0
0
1
2
7
July
Dec.
0
0
1
1
2
8
June
Latitude 30°
11
10
9
8
7
6 A.M.
North
Noon
1
2
3
4
5
6 P.M.
South
June
0
0
0
0
1
1
4
Dec.
July
Jan.
May
0
0
0
0
1
1
4
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
7
Oct.
Sept.
Mar.
Mar.
0
0
0
1
1
3
Sept.
Oct.
Apr.
Feb.
0
0
0
1
2
6
Aug.
Nov.
May
Jan.
0
1
1
1
3
July
Dec.
1
1
1
2
4
June
Latitude 40°
11
10
9
8
7
6
5 A.M.
North
Noon
1
2
3
4
5
6
7 P.M.
South
June
0
0
0
0
1
1
3
9
Dec.
July
Jan.
May
0
0
0
0
1
1
3
Nov.
Aug.
Feb.
Apr.
0
0
0
0
1
2
6
Oct.
Sept.
Mar.
Mar.
0
0
0
1
1
4
Sept.
Oct.
Apr.
Feb.
1
1
1
1
3
10
Aug.
Nov.
May
Jan.
1
1
1
2
5
July
Dec.
1
1
2
3
7
June
Latitude 50°
11
10
9
8
7
6
5 A.M.
North
Noon
1
2
3
4
5
6
7 P.M.
South
June
0
0
0
0
1
1
2
5
Dec.
July
Jan.
May
0
0
0
0
1
1
2
7
Nov.
Aug.
Feb.
Apr.
0
0
0
1
1
2
5
Oct.
Sept.
Mar.
Mar.
0
1
1
1
2
4
Sept.
Oct.
Apr.
Feb.
1
1
1
2
4
Aug.
Nov.
May
Jan.
2
2
3
4
July
Dec.
2
2
4
6
June
Latitude 60°
11
10
9
8
7
6
5
4 A.M.
North
Noon
1
2
3
4
5
6
7
8 P.M.
South
June
0
0
0
0
1
1
2
3
6
Dec.
July
Jan.
May
0
0
0
1
1
1
2
4
10
Nov.
Aug.
Feb.
Apr.
0
0
1
1
1
2
4
Oct.
Sept.
Mar.
Mar.
1
1
1
2
3
6
Sept.
Oct.
Apr.
Feb.
2
2
3
4
9
Aug.
Nov.
May
Jan.
4
5
7
July
Dec.
6
7
June
Latitude 70°
11
10
9
8
7
6
5
4
3
2
1 A.M.
North
Noon
1
2
3
4
5
6
7
8
9
10
11 P.M.
Midnight
South
June
0
0
0
1
1
1
2
2
3
5
7
9
10
Dec.
July
Jan.
May
0
1
1
1
1
1
2
3
5
7
Nov.
Aug.
Feb.
Apr.
1
1
1
1
2
2
4
7
Oct.
Sept.
Mar.
Mar.
2
2
2
3
4
8
Sept.
Oct.
Apr.
Feb.
5
5
7
Aug.
Latitude 80°
11
10
9
8
7
6
5
4
3
2
1 A.M.
North
Noon
1
2
3
4
5
6
7
8
9
10
11 P.M.
Midnight
South
June
1
1
1
1
1
1
1
2
2
2
3
3
3
Dec.
July
Jan.
May
1
1
1
1
1
1
2
2
3
3
4
4
4
Nov.
Aug.
Feb.
Apr.
2
2
2
2
2
3
4
5
7
9
Oct.
Sept.
Mar.
Mar.
4
4
5
6
8
Sept.
Latitude 90°
North
All hours
South
June
1
Dec.
July
Jan.
May
2
Nov.
Aug.
Feb.
Apr.
4
Oct.
Table XIII
Numerical values which characterize the atmospheric conditions indicated in Column 1.
Atmospheric conditions
Sun B
Sky illuminance foot-lamberts
Luminance density foot-lumergs
Rel. camera exposure Ra
Atmospheric index A
Max.
Avg.
Min.
Vd
Vs
Vt
Perfectly clear
500×106
(3)
1,400
740
(2)
400
110
15
125
—
—
Clear
450×106
(1)
6,000
1500
(4)
650
97.6
30.4
128
1.0
0
Light haze
14×106
(1)
100,000
4300
(4)
1800
3.1
87.9
91
1.4
1.5
Medium haze
450×103
(1)
25,000
3150
1500
0.097
63.9
64
2.0
3
Heavy haze
15×103
(1)
8,000
2150
1200
0.003
44
44
3.2
5
Light cloud
0
(1)
4,000
1750
1000
0
36
36
Medium cloud
0
(2)
2,500
1300
(3)
650
0
26
26
5
7
Heavy cloud
0
(2)
1,200
640
(3)
400
0
13
13
10
10
Dense cloud
0
(2)
400
200
(3)
150
0
4
4
32
15
near sun
near zenith
near horizon
approximately 90° from sun, measured through zenith.
Table XIV
Atmospheric index, A, for various atmospheric conditions.