Lines of
Resolution:
A Surveillance Camera's performance is based on the
number of horizontal lines that the chip in the camera provides. The
lines of resolution determines the quality of the video the camera can
produce. The higher the number of lines of resolution, the better the
video quality is.
|
Performance |
Color |
B/W |
|
Standard |
330 Lines |
380 Lines |
|
Medium |
420 Lines |
470 Lines |
|
High |
480 Lines |
580 Lines |
Lens:
The lens determines the
field of view the camera provides. Lenses range from 2.8mm to 18mm on an
average. The larger the lens size the farther it will view. The draw
back to a 12mm or 18mm lens is that the horizontal view narrows to as
little as 15 feet.
|
Lens |
Distance |
Width |
|
2.8 mm |
10 feet |
15 feet |
|
3.6mm |
30 feet |
30 feet |
|
6 mm |
60 feet |
20 feet |
*Many of our customers require a standard fixed wide angle 3.6mm
lens. They are designed to be installed in a corner, provide a 90 degree
field of view, and provide effective surveillance in a 30 x 30 foot
area. If you need to adjust the angle and are not sure when viewing a
cash register or looking down aisles, we recommend a vari-focal lens
which you can adjust manually based on the angle and distance of the
camera to the subject. For example, with a cash register we recommend a
4-8mm vari-focal lens so you can manually adjust and capture the money,
hands, and register close up. When in doubt, go with a vari-focal
adjustable lens.
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. |
|
|
