Lens Info
How to select a proper security camera lens in 3 easy steps and save money doing it?
1. Should I use Manual Iris, Auto Iris or DC lens?
- You can save money and use manual iris lens only when scene illumination never changes. Example: illuminated store or office.
- If the light changes a lot it is recommended using auto-iris
2. What focal length lens do I need?
- Guide: smaller the focal length number => wider is field of view.
- If you have securit camera in the office or warehouse and you want to see as much as you can, you should go for 2.8 or 4 mm lens (makes wide, somewhat distant view)
- If you want to observe limited area, like entrance you should go for 8mm or (makes narrow view and objects are closer).
- Give us a call and we can help you determine what security camera lens will best suit your location.
- Use varifocal lenses to get flexibility for choosing best field of view.
The CCTV security camera lens chartand field-of-view diagrams are designed to assist you in selecting the right lens size for your application. Please contact us if you require additional information or assistance. Keep in mind all of the security cameras we sell come equipped with lenses that will achieve 95% of your surveillance applications.
|
Lux and low lighting chart |
| Condition |
Illumination |
Details |
| (FTCD) |
(LUX) |
Sunlight
Full Daylight
Overcast Day
Very Dark Day
Twilight
Deep Twilight |
10,000
1,000
100
10
1
.1 |
107,527
10,752.7
1,075.3
107.53
10.75
1.08 |
Daylight
Range |
Full Moon
Quarter Moon
Starlight
Overcast Night |
.01
.001
.0001
.00001 |
.108
.0108
.0011
.0001 |
Low Light
Level Range |
During the day the amount of illumination reaching a scene depends on the time of day and atmospheric conditions. Direct sunlight produces the highest-contrast scene, allowing maximum identification of objects. On a cloudy or overcast day, less light is received by the objects in the scene, resulting in less contrast. To produce an optimum camera picture under the wide variation in light level (such as occurs when the sun is obscured by clouds), an automatic-iris camera system is required. Typically, scene illumination measured in foot-candles (ftcd) can vary over a range of 10,000 to 1 (or more), which exceeds the operating range of most cameras for producing good quality video /images. The chart above summarizes the light levels occurring under daylight and these low light level conditions. The equivalent metric measure of light level (lux) compared with the English (ftcd) is given.
|
The following chart displays the comparision of CCTV lens with the regular 135mm film camera lens.
|
CCTV lens |
135mm lens |
|
|
|
Focal Length |
Angle |
Angle |
Focal Length |
|
|
|
2.5mm |
120° |
114° |
14mm |
|
|
|
3.6mm |
92° |
94° |
20mm |
|
|
|
4.3mm |
78° |
75° |
28mm |
|
|
|
6.0mm |
53° |
51° |
45mm
Standard lens for 135mm camera Regular angle of our eyes vision |
|
|
|
12mm |
25° |
24° |
100mm |
|
|
|
25mm |
18° |
18° |
135mm |
|
|
Indicates total viewable area (WxH) at a given distance based on focal length used
|
| Focal Length |
5' (WxH) |
10' (WxH) |
20' (WxH) |
40' (WxH) |
50' (WxH) |
100' (WxH) |
| 2.5 mm |
9.4x7.1 |
19x14 |
38x28 |
75x57 |
94x71 |
188x142 |
| 2.9 mm |
8.6x6.4 |
17x13 |
34x26 |
69x51 |
86x64 |
171x129 |
| 3.6 mm |
6.9x5.1 |
14x10 |
27x21 |
55x41 |
69x51 |
137x103 |
| 4.0 mm |
6.0x4.5 |
12x9 |
24x18 |
48x36 |
60x45 |
120x90 |
| 4.3 mm |
5.7x4.3 |
11x8.6 |
23x17 |
46x34 |
57x43 |
114x86 |
| 5.5 mm |
4.5x3.4 |
9x6.8 |
18x14 |
36x27 |
45x34 |
90x68 |
| 6.0 mm |
2.0x1.5 |
4x3 |
8x6 |
16x12 |
20x15 |
40x30 |
| 8.0 mm |
1.5x1.1 |
3x2.3 |
6x4.5 |
12x9 |
15x11 |
30x22 |
| 12.0 mm |
1.0x0.7 |
2x1.4 |
3.8x3 |
7.7x6 |
9.6x7 |
19x14 |
Use your 35mm camera and this chart to help make your lens decision.
|
35 mm |
1/4" |
1/3" |
1/2" |
2/3" |
1" |
Angle |
|
10 |
0.9 |
1.4 |
1.8 |
2.5 |
3.7 |
120.6 |
|
35 |
3.2 |
4.8 |
6.4 |
8.8 |
12.8 |
53.2 |
|
60 |
5.5 |
8.2 |
11.0 |
15.1 |
22 |
32.6 |
|
85 |
7.7 |
11.6 |
15.6 |
21.3 |
31.1 |
23.3 |
|
110 |
10.0 |
15.1 |
20.1 |
27.6 |
40.3 |
18.1 |
|
135 |
12.3 |
18.5 |
24.7 |
33.9 |
49.4 |
14.8 |
|
160 |
14.6 |
21.9 |
29.3 |
40.2 |
58.6 |
12.5 |
|
185 |
16.8 |
25.3 |
33.9 |
46.4 |
67.7 |
10.8 |
|
210 |
19.1 |
28.8 |
38.4 |
52.7 |
76.9 |
9.5 |
|
235 |
21.4 |
32.2 |
43.0 |
59.0 |
86.0 |
8.5 |
|
260 |
23.7 |
35.6 |
47.6 |
65.3 |
95.2 |
7.7 |
CCTV focal length numbers shown converted from a 35mm camera zoom lens.
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