The lens is the eye of the camera and can be said to be the determining factor of the camera's sharpness. In order to capture a clear picture, it is essential to choose a suitable lens, but at present, various types of surveillance camera lenses must be seen when purchasing.
Driving monitoring is becoming more and more obvious. You can know the camera lens selection.
Matching of the lens mount. That is, C and CSMount must match each other. Of course, in the current majority of the use of 5mm mating ring, this problem is not big, but the failure in the installation process is endless.
The aperture range is large, that is, the larger the value range of the f value from small to large, the better, so that the matching camera can adapt to the ambient light conditions to cope with any change of illumination conditions;
The lens coating should be uniform. At present, the coating of higher quality lenses is a multi-layer composite coating. The composite coating can effectively suppress backlighting and light scattering, so that the camera avoids the adverse effects caused by light;
Aspherical lens matching applications, regardless of the million or non-million camera applications, with the aspherical mirror to improve the overall average of the camera screen light. Because the aspherical lens has better effects on the sharpness, contrast, and brightness of the screen than the spherical lens;
It is best to use an adjustment screw with a fixed focus on the focal length, depth of field or aperture. Because the lens is used in a variety of different environments and fixed conditions, if this device can avoid the picture quality changes caused by the camera shake caused by the camera shake; choose a camera that is convenient to install and fit the lens structure, too large or too small The lens will cause inconvenience to the camera installation adjustment or construction, especially the lens with more complicated structure needs to be used with caution;
The choice of infrared lens is not absolute, and it should be cautious when matching Day (Day & Night) day and night cameras with (Low-Light) low illumination cameras. The ICR (color-to-black) camera has no preference for IR lenses. On the contrary, in black-and-white conditions, the IR lens may be an excessive waste of function;
The lens (LD low scattering optical lens) lens is selected by the camera's sensing range of the infrared wave field. Generally, the infrared sensing wavelength of IR is about 300-750 nm. However, if there is a need for fogging, the camera and the lens must reach the range of 700-950 nm in the infrared sensing wavelength, because only the wavelength reaches this range. The effect of fogging; the lens must also pay attention to the matching of the caliber in the camera. In the past, the simple 1/2, 1/3 and 1/4 inch caliber is not the law. With the development of CMOS sensor, more and more The size of the image is larger, and the principle that the lens is larger than the aperture of the camera remains unchanged. However, this principle also has the wrong selection application in engineering.
With the development of high-definition surveillance becoming more and more obvious, the security industry technology is slowly maturing, and the emergence of high-definition cameras has greatly improved the image quality of security systems. For security systems, especially for road monitoring applications, the lens is required to have high resolution in all viewing angles. For example, with 1080p HD cameras, the resolution of the lens is required to be 2M or more. In short, it is the MTF of the lens. The graph has higher requirements.
In the general monitoring system, especially in the road monitoring system, the illumination changes throughout the day is very large. In addition to ensuring good imaging quality in the lens F8 aperture first, the lens for night long-distance monitoring has sufficient F value. Small to ensure good image quality in a large relative diameter. Of course, the smaller the F value, the more expensive the lens is. For a zoom lens with a large multiple, the lens price is much higher than the price of other parts of the camera. In the road monitoring system, especially the urban and night use lens selected in the urban road monitoring, in addition to the aperture value of the lens, it is necessary to comprehensively consider the infrared light correction under the lighting conditions to ensure the clarity of the imaging.
Outdoor monitoring systems generally require the use of an auto iris lens due to large changes in illumination. Of course, the actual amount of light passing through the lens is related to other factors besides the F value, such as the coating, the material of the lens, and the size of the lens itself. The same F value was found in the test, and the actual amount of light passing will differ by 20.
What types of surveillance lenses are available (classified by application)
Wide-angle lens: The viewing angle is above 90 degrees, the viewing range is large, and the near image is deformed.
Standard lens: The viewing angle is about 30 degrees, and the range of use is wide.
Telephoto lens: The viewing angle is within 20 degrees, and the focal length can reach several tens of millimeters or hundreds of millimeters.
Zoom lens: The focal length of the lens is continuously variable, and the focal length can be changed from wide angle to telephoto. The longer the focal length, the larger the image.
Fine lens: used for concealed observation, often installed in places such as ceilings or walls.
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