How to choose a low light camera?

With the development of semiconductor technology in recent years, ultra-low illumination camera is a popular product in monitoring industry. At present, it has been widely used in finance, culture, hotels, office buildings, residential property management and other fields. Because the traditional camera can't meet the demand of 24-hour continuous monitoring (because it is impossible to turn on the light anywhere for 24 hours), the ultra-low illumination camera based on new technology seized this opportunity and developed rapidly. General ultra-low illumination cameras mostly use exview had technology, and the sensitivity of cameras using exview had ccd to external light will be greatly improved, and the sensitivity in the near infrared region can be improved to four times that of ordinary cameras, as shown in figure 1. Therefore, even in a very dark environment, this kind of camera can usually see objects that people can't see. The emergence of this technology has been welcomed by the monitoring market, and it can show the best effect in all kinds of lighting environments, especially with special infrared lighting equipment, which can obtain high-definition black and white images and realize the monitoring of 0 illumination (without lighting at all). In the near infrared region of 760mm- 1 100mm, a clear black-and-white image can be obtained if infrared illumination with appropriate wavelength is used. Similarly, the method of acquiring images in low illumination is to increase the exposure of ccd in a single frame image by accumulating charges in a single frame, thus improving the sensitivity of the camera to a single frame image. This method can also get a lower illumination index, but it needs to reduce the consistency of the image. Therefore, when choosing this camera, we should pay attention not to cooperate with the pan/tilt as much as possible, otherwise it will cause the phenomenon of picture loss. There are some other methods to obtain images in low illumination, but none of them can fundamentally solve the illumination problem. In addition, we should pay attention to several points when choosing to use low-light camera and infrared lamp. First of all, choose the right lens. In order to improve the sensitivity of the camera to infrared light and scenery, choose a lens with a large amount of light as much as possible, and pay attention to opening the driving stage of the aperture as much as possible when using automatic aperture or electric variable lens. Because generally, with the increase of lens focal length, the luminous flux will decrease relatively, so we should leave a certain margin when choosing infrared lamps, and pay attention to the nominal index of infrared lamps. Secondly, the matching power supply of infrared lamp should try to meet the minimum electric power required, and the irradiation distance is often not enough. Third, we should consider the degree of reflection of the shooting scene. Because infrared ray has the same reflection and refraction characteristics as visible light, if there is no good reflection environment around the target scene (such as buildings, fences and signs), a certain distance margin should be considered.