An IP surveillance camera’s light sensitivity is often specified
in terms of lux, which corresponds to a level of illuminance in which a camera
produces an acceptable image. The lower the lux specification, the better light
sensitivity the camera has. Normally, at least 200 lux is needed to illuminate
an object so that a good quality image can be obtained. In general, the more
light on the subject, the better the image. With too little light, focusing
will be difficult and the image will be noisy and/or dark. To capture good
quality images in low light or dark conditions, a day and night camera that
takes advantage of near-infrared light is required.
Different light conditions offer different illuminance. Many
natural scenes have fairly complex illumination, with both shadows and
highlights that give different lux readings in different parts of a scene. It
is important, therefore, to keep in mind that one lux reading does not indicate
the light condition for a scene as a whole.
Examples of different levels
of illuminance
100,000 lux……..Strong sunlight
10,000 lux …….. Full daylight
500 lux ………… Office light
100 lux …………Poorly lit room
Many manufacturers specify the minimum level of illumination
needed for an IP surveillance camera to produce an acceptable image. While such
specifications are helpful in making light sensitivity comparisons for cameras
produced by the same manufacturer, it may not be helpful to use such numbers to
compare cameras from different manufacturers. This is because different
manufacturers use different methods and have different criteria for what is an
acceptable image.
To properly compare the low light performance of two different
cameras, the cameras should be placed side by side and be viewing a moving
object in low light.
