There are lots of CCTV cameras for the safety of a housing estate, traffic, public places, many of which areIR CCTV cameras. Many customers perfer to buy the those camera that is able to get a good shooting at night. The IR CCTV camera can get colorful pics during the day and black and white at night. Therefore, when choosing CCTV camera lens, technical basis as follows:
1. The image size
It should be consistent with the size of the CCD. In the security industry, it usually has 1/2 inch, 1/3 inch, 1/4 inch and others.
2. The resolution of lens
As for the size of the CCD standard, 1/3 inch CCTV camera is 4.8mm width and 3.6mm height. For the 1/3 inch CCTV camera, CCD is smaller and the resolution of lens is required higher.
3. The focal length of the lens and viewing angle
According to the distance between CCTV camera and the monitored object, we choose the focal length of the Lens. When the focal lens F confirmed, the viewing angle is determined by the target surface of CCTV camera.
4. Luminous flux is measured by the ratio of the focal length of lens and the aperture. We mark F. Every lens has its max F. It usually has F1.0/ F1.2/ F1.4 and so on. The luminous flux is inversely proportional to the F value squared. The smaller F value is, the bigger the luminous flux is. We can choose the manual luminous flux or the auto luminous flux according to the light change of monitoring places.
So the lens plays an important role in the quality of CCTV camera. We can not judge a good CCTV camera only from the CCD. There are many other factors to determine the quality of CCTV camera, like the lens.
It should be consistent with the size of the CCD. In the security industry, it usually has 1/2 inch, 1/3 inch, 1/4 inch and others.
2. The resolution of lens
As for the size of the CCD standard, 1/3 inch CCTV camera is 4.8mm width and 3.6mm height. For the 1/3 inch CCTV camera, CCD is smaller and the resolution of lens is required higher.
3. The focal length of the lens and viewing angle
According to the distance between CCTV camera and the monitored object, we choose the focal length of the Lens. When the focal lens F confirmed, the viewing angle is determined by the target surface of CCTV camera.
4. Luminous flux is measured by the ratio of the focal length of lens and the aperture. We mark F. Every lens has its max F. It usually has F1.0/ F1.2/ F1.4 and so on. The luminous flux is inversely proportional to the F value squared. The smaller F value is, the bigger the luminous flux is. We can choose the manual luminous flux or the auto luminous flux according to the light change of monitoring places.
So the lens plays an important role in the quality of CCTV camera. We can not judge a good CCTV camera only from the CCD. There are many other factors to determine the quality of CCTV camera, like the lens.
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