Thursday, April 26, 2012

Camera and Focal Length


A week-long vacation in Florida, five theme parks in a row, presented me with a garden variety of cameras used by tourists from all over the world.  Even within my own family, we used at least four cameras: Nikon Coolpix S3000, Canon PowerShot SD550, Sony Nex 5N, Nikon D3S. Not counting iPhone 4S and Blackberry Bold.  

Yes, he is taking a photo, not reading an ebook.
I brought with me a Nikon 24-300 zoom FX lens, among a couple of other lenses.  I got the lens about a year ago--acting in part on a whimsical reaction to a reviewer's funny, casual comment at YouTube. (At 5 minute and 21 second.)  I had used the lens in the past but never as extensively as I did on this trip.  Overall, I took over 6,300 photos on this lens, from group photos or landscape to architectural elements at a distance, from still portraits to moving targets (e.g. roaming animals and performing actors), and from extremely dark environments to high contrast situations.  I really like the image quality, flexibility and portability this lens, coupled with a D3S,  affords.


Given the large number of photos, a quick analysis, even if a simple one,  on the relative frequency of various focal lengths actually used during the trip should be statistically meaningful.   Here are some observations (Tables 1-3), most of which simply confirm the well-known facts in the industry:

  1. 28mm has the highest frequency (20.3%), followed by 300 mm (8.9%).  This is very surprising as it indicates focal lengths on both ends of the lens got used the most.  The two lengths constitute close to 30% or 1/3 of the usage. 
  2. 48 mm has the third highest frequency (3.6%).  This justifies the common use of 50 mm-lenses. 
  3. Lens range from 28-70 mm covers close to 60% of uses.  This makes perfect sense.
  4. Lens range from 70-200 mm covers close to 30% of uses.  This also makes sense.
  5. Not surprisingly, a 28-70 mm and a 70-200 mm lens will be sufficient for 90% of the situations.
  6. Extra focal length above 200 mm is still useful, about 13%.
  7. Frequency for 85 mm, based on the uses from 78mm to 90mm, is 7.8% (calculation not shown), or close to 10%, significant enough to justify the purchase of a 85 mm lens.  


Table 1 Focal Length (mm) Frequency (%) Distribution

f (mm)
Photo #
%
28
1292
20.29
32
180
2.83
34
104
1.63
35
93
1.46
36
88
1.38
38
115
1.81
40
159
2.50
42
129
2.03
44
132
2.07
45
125
1.96
48
229
3.60
50
125
1.96
52
138
2.17
55
132
2.07
56
113
1.77
58
114
1.79
62
215
3.38
65
86
1.35
68
133
2.09
70
80
1.26
72
97
1.52
78
139
2.18
82
148
2.32
85
121
1.90
90
88
1.38
92
99
1.55
98
106
1.66
100
103
1.62
105
99
1.55
112
81
1.27
116
73
1.15
122
79
1.24
125
62
0.97
135
127
1.99
145
60
0.94
150
48
0.75
160
71
1.11
170
50
0.79
180
67
1.05
190
56
0.88
200
34
0.53
210
74
1.16
230
69
1.08
250
69
1.08
300
567
8.90
Total
6369
100.00






















































Tab 2  Focal Length Frequency (%) in Descending Order

f (mm)
Photo #
%
28
1292
20.29
300
567
8.90
48
229
3.60
62
215
3.38
32
180
2.83
40
159
2.50
82
148
2.32
78
139
2.18
52
138
2.17
68
133
2.09
44
132
2.07
55
132
2.07
42
129
2.03
135
127
1.99
45
125
1.96
50
125
1.96
85
121
1.90
38
115
1.81
58
114
1.79
56
113
1.77
98
106
1.66
34
104
1.63
100
103
1.62
92
99
1.55
105
99
1.55
72
97
1.52
35
93
1.46
36
88
1.38
90
88
1.38
65
86
1.35
112
81
1.27
70
80
1.26
122
79
1.24
210
74
1.16
116
73
1.15
160
71
1.11
230
69
1.08
250
69
1.08
180
67
1.05
125
62
0.97
145
60
0.94
190
56
0.88
170
50
0.79
150
48
0.75
200
34
0.53
Total
6369
100.00



Tab3  Focal Length Range Frequency (%)

Lens Range (mm)
Frequency (%)
18-50
43.51
28-70
59.38
70-200
28.39
70-300
41.87
100-300
28.09
200-300
12.76




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