H. S. Coleman and W. S. Verplanck, "A Comparison of Computed and Experimental Detection Ranges of Objects Viewed with Telescopic Systems from Aboard Ship*," J. Opt. Soc. Am. 38, 250-253 (1948)
The relative range performance of approximately 80 telescopic systems of 18 different designs has been determined by statistical methods based on the results of a field test conducted from shipboard. The range at which objects are detectable from aboard ship is compared with the range computed from laboratory measurements of light transmission, magnification, exit pupil, and contrast rendition, using a method described by Hardy and the data of Duntley and Blackwell on the characteristics of the atmosphere and the human eye. The agreement between the results of the field tests and the computations is extraordinary. This is interpreted to mean that the most important factors were taken into account in both the statistical and computational procedures. This implies that if a visibility field test is properly conducted, the results can be expected to agree with those of simulated laboratory tests, and conversely, that properly constructed laboratory tests will yield data which predict accurately the performance of instruments in the field.
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Laboratory data for instruments used in field tests.
Contrast rendition
Exit pupil
Transmission
Magnification
Instrument
Day
Night
Day
Night
4×28×10°
95
85
2.5 mm
7 mm
6×30×8.5°
98
96
2.5 mm
5 mm
0.47
6
6×33×8°
91
75
2.5 mm
5.5 mm
0.45
6
6×42×12°
96
82
2.5 mm
7 mm
0.66
6
6×50×7°
97
90
2.5 mm
—
0.66
6
7×50×7.1°
97
92
2.5 mm
7 mm
0.70
7
7×50×10°
97
87
2.5 mm
7 mm
0.70
7
8×60×8°
97
92
2.5 mm
7.5 mm
0.65
8
9×63×5.7°
96
94
2.5 mm
7 mm
0.72
9
10×50×7°
98
91
2.5 mm
5 mm
0.76
10
10×70×7°
90
82
2.5 mm
7 mm
0.66
10
10×80×7°
88
86
2.5 mm
8 mm
0.48
10
20×120×3°
96
94
2.5 mm
6 mm
0.61
20
21×76×2.8°
96
94
2.5 mm
3.5 mm
0.50
21
25×100×3.6°
94
92
2.5 mm
4 mm
0.65
25
7×50×7.1°
96
93
2.5 mm
7 mm
0.70
7
7×50×7.1°
96
91
2.5 mm
7 mm
0.70
7
10×70×7°
93
75
2.5 mm
7 mm
0.40
10
7×50×7.1°
95
92
2.5 mm
7 mm
0.66
7
Table II
Computed vs. field performance (relative to mounted 7×50×7.1° binoculars) of mounted binoculars at night.*
Description of instrument
Computed performance
Field performance
6×33×7°
76%
73%
6×42×7°
88
76
6×50×7°
102
80
10×70×7°
116
104
7×50×7.1°
100
100
10×50×7°
106
106
10×80×7°
118
115
25×100×3.6°
159
156
20×120×3°
163
163
Field test range for mounted 7×50×7.1° binoculars—2630 yds. Computed liminal range for 7×50×7.1° binocular—2180 yds.
Table III
Computed vs. field performance of hand-held binoculars at night.*
Description of instruments
Computed performance
Field performance Based on 7×50×7.1° binoculars
Hand-held
Mounted
6×42×12°
83%
95%
82%
7×50×10°
95
103
89
8×60×7°
113
104
90
9×63×5.7°
119
112
97
10×50×7°
106
117
101
Field test range for hand-held 7×50×7.1° binoculars—2270 yds. Field test range for mounted 7×50×7.1° binoculars—2630 yds. Computed liminal range for 7×50×7.1° binocular—2180 yds.
Table IV
Computed vs. field performance (relative to mounted 7×50×7.1° binocular) of mounted monoculars at night.*
Description of instrument
Computed performance
Field performance
4×28×10°
59%
46%
6×30×8.5°
70
46
6×33×8°
62
56
21×76×2.8°
140
69
Field test range for mounted 7×50×7.1° binocular—2630 yds. Computed liminal range for 7×50×7.1° binocular—2180 yds.
Table V
Computed vs. field performance for hand-held and mounted instruments at night.*
Description of instrument
Computed performance
Field performance
7×50×7.1° (H. H.)
100%
100%
7×50×7.1° (H. H.)
100
91
10×70×7° (Mtd.)
96
92
7×50×7.1° (Mtd.)
98
115
Computed liminal range for a 7×50×7.1° binocular—2180 yds.
Table VI
Computed vs. field performance (relative to hand-held 7×50×7.1° binoculars) for hand-held or mounted instruments in daylight.†
Description of instrument
Computed performance
Field performance
7×50×7.1° (H. H.)
100%
100%
7×50×7.1° (H. H.)
100
—
10×70×7° (Mtd.)
110
—
7×50×7.1° (Mtd.)
100
115
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Table VII
Computed vs. field performance (relative to hand-held 7×50×7.1° binoculars) of hand-held binoculars in daylight.†
Description of instrument
Computed performance
Field performance
10×50×7.1°
110%
100%
7×50×7.1°
100
99
6×42×12°
97
100
7×50×10°
100
102
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Table VIII
Computed vs. field performance (relative to mounted 7×50×7.1° binoculars) of mounted binoculars in daylight.†
Description of instrument
Computed performance
Field performance
7×50×7.1°
100%
100%
10×80×7°
109
102
10×50×7°
111
105
25×100×3.6°
122
153
20×120×3°
120
173
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Table IX
Computed vs. field performance (relative to mounted 7×50×7.1° binoculars) of mounted monoculars in daylight.‡
Description of instrument
Computed performance
Field performance
6×33×7°
96%
84%
4×28×10°
84
87
6×33×8°
95
90
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Tables (9)
Table I
Laboratory data for instruments used in field tests.
Contrast rendition
Exit pupil
Transmission
Magnification
Instrument
Day
Night
Day
Night
4×28×10°
95
85
2.5 mm
7 mm
6×30×8.5°
98
96
2.5 mm
5 mm
0.47
6
6×33×8°
91
75
2.5 mm
5.5 mm
0.45
6
6×42×12°
96
82
2.5 mm
7 mm
0.66
6
6×50×7°
97
90
2.5 mm
—
0.66
6
7×50×7.1°
97
92
2.5 mm
7 mm
0.70
7
7×50×10°
97
87
2.5 mm
7 mm
0.70
7
8×60×8°
97
92
2.5 mm
7.5 mm
0.65
8
9×63×5.7°
96
94
2.5 mm
7 mm
0.72
9
10×50×7°
98
91
2.5 mm
5 mm
0.76
10
10×70×7°
90
82
2.5 mm
7 mm
0.66
10
10×80×7°
88
86
2.5 mm
8 mm
0.48
10
20×120×3°
96
94
2.5 mm
6 mm
0.61
20
21×76×2.8°
96
94
2.5 mm
3.5 mm
0.50
21
25×100×3.6°
94
92
2.5 mm
4 mm
0.65
25
7×50×7.1°
96
93
2.5 mm
7 mm
0.70
7
7×50×7.1°
96
91
2.5 mm
7 mm
0.70
7
10×70×7°
93
75
2.5 mm
7 mm
0.40
10
7×50×7.1°
95
92
2.5 mm
7 mm
0.66
7
Table II
Computed vs. field performance (relative to mounted 7×50×7.1° binoculars) of mounted binoculars at night.*
Description of instrument
Computed performance
Field performance
6×33×7°
76%
73%
6×42×7°
88
76
6×50×7°
102
80
10×70×7°
116
104
7×50×7.1°
100
100
10×50×7°
106
106
10×80×7°
118
115
25×100×3.6°
159
156
20×120×3°
163
163
Field test range for mounted 7×50×7.1° binoculars—2630 yds. Computed liminal range for 7×50×7.1° binocular—2180 yds.
Table III
Computed vs. field performance of hand-held binoculars at night.*
Description of instruments
Computed performance
Field performance Based on 7×50×7.1° binoculars
Hand-held
Mounted
6×42×12°
83%
95%
82%
7×50×10°
95
103
89
8×60×7°
113
104
90
9×63×5.7°
119
112
97
10×50×7°
106
117
101
Field test range for hand-held 7×50×7.1° binoculars—2270 yds. Field test range for mounted 7×50×7.1° binoculars—2630 yds. Computed liminal range for 7×50×7.1° binocular—2180 yds.
Table IV
Computed vs. field performance (relative to mounted 7×50×7.1° binocular) of mounted monoculars at night.*
Description of instrument
Computed performance
Field performance
4×28×10°
59%
46%
6×30×8.5°
70
46
6×33×8°
62
56
21×76×2.8°
140
69
Field test range for mounted 7×50×7.1° binocular—2630 yds. Computed liminal range for 7×50×7.1° binocular—2180 yds.
Table V
Computed vs. field performance for hand-held and mounted instruments at night.*
Description of instrument
Computed performance
Field performance
7×50×7.1° (H. H.)
100%
100%
7×50×7.1° (H. H.)
100
91
10×70×7° (Mtd.)
96
92
7×50×7.1° (Mtd.)
98
115
Computed liminal range for a 7×50×7.1° binocular—2180 yds.
Table VI
Computed vs. field performance (relative to hand-held 7×50×7.1° binoculars) for hand-held or mounted instruments in daylight.†
Description of instrument
Computed performance
Field performance
7×50×7.1° (H. H.)
100%
100%
7×50×7.1° (H. H.)
100
—
10×70×7° (Mtd.)
110
—
7×50×7.1° (Mtd.)
100
115
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Table VII
Computed vs. field performance (relative to hand-held 7×50×7.1° binoculars) of hand-held binoculars in daylight.†
Description of instrument
Computed performance
Field performance
10×50×7.1°
110%
100%
7×50×7.1°
100
99
6×42×12°
97
100
7×50×10°
100
102
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Table VIII
Computed vs. field performance (relative to mounted 7×50×7.1° binoculars) of mounted binoculars in daylight.†
Description of instrument
Computed performance
Field performance
7×50×7.1°
100%
100%
10×80×7°
109
102
10×50×7°
111
105
25×100×3.6°
122
153
20×120×3°
120
173
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
Table IX
Computed vs. field performance (relative to mounted 7×50×7.1° binoculars) of mounted monoculars in daylight.‡
Description of instrument
Computed performance
Field performance
6×33×7°
96%
84%
4×28×10°
84
87
6×33×8°
95
90
Computed liminal range for a 7×50×7.1° binocular—16,400 yds.
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