What is Day Night Function for Security Camera?

Since security cameras are not devices operating under a single condition, it is necessary to ensure that they are as smooth as possible in all circumstances.

For example; The conditions of the environment are evident when you take a handheld camera in a room and shoot. Conditions such as lighting level, humidity are constant or vary by up to 5%. In this case, since the handheld camera captures the image under the same conditions, the entire image is more or less the same.

In particular, security cameras installed to monitor outside the building are exposed to all kinds of light, moisture and fog conditions. Since the transition from day to night and the transition from evening to day does not change as if turning the light off momentarily, the camera must adapt to the light conditions in between. If there is no other source of illumination in a closed sky without the moon, the brightness of the environment is 0.0001 lux. Ambient brightness in the summer sunshine is between 10,000 ~ 25,000 lux. In other words, the security camera should be working correctly under these two light conditions and the conditions in between so that it can serve its purpose.

In addition, the cameras are highly sensitive to visible light as well as infrared wavelength radiation. In the daytime, especially in the presence of visible light, as well as infrared radiation is very high. Camera manufacturers follow two paths to prevent infrared radiation from glaring on the image.

• Cover the CCD or CMOS sensor with a non-infrared filter (which also means reducing the amount of light passing through the camera's sensor).
• By placing a filter in front of the CCD or CMOS sensor, taking a filtered daylight with plenty of light and unfiltered shooting in the night when light is insufficient.

The cameras produced according to the first case are called electronic day and night function cameras. Because these cameras try to perform the day and night function electronically. However, since the filter is adherent to the sensor, they cannot detect the light of the infrared illumination. In addition, since there is a continuous filter in front of it, the sensitivity of light is only as much as the capability of electronic circuits and they can only detect the light passing through the filter and produce images.

However, the cameras produced with the moving filter do not pass the infrared radiation through the day filter and give the correct image, while the night filter starts to receive the radiation at each wavelength. This increases the camera's sensitivity to light. Also, to prevent infrared radiation from shining and distorting colors on the image, the camera turns off night color marks to reduce glare as much as possible and give a smooth image all around.

As a result, the day and night function can be described as follows: The fact that security cameras shoot without daytime glare is an arrangement for shooting at night with increased sensitivity to light. The camera takes a filtered color image during daytime when there is plenty of light, and switches to black and white image capture at night when the light is low.

Ambient brightness values ​​according to conditions;

Luminous Value            Ambient Description

• 0,0001 lux                   Night, Moonless, Covered Sky
• 0.002 lux                      Night, No Moon, Clear Sky
• 0.27 ~ 1 lux                  Night, Full Moon and Clear Sky
• 3.4 lux                           Clear Sky and Dawn Time
• 50 lux                            Daytime, Interior with Window
• 80 lux                            Entrance of Large Office Buildings
• 100 lux                          Daytime, Extreme Covered Sky
• 320-500 lux                  Daytime, In-Office
• 400 lux                          Sunset
• 1000 lux                        Daytime Covered Sky
• 10,000 ~ 25,000 lux     Daytime, Full Sunshine, Clear Sky
• 32,000 ~ 130,000 lux   Direct Incoming Sunlight