The important few things for how to buy and how to install security cameras correctly

20 Mar



The role of security cameras for monitoring the imaging region and converts it into an electrical signal , according to the specification can be divided into 1/ 3 “, 1 / 2″ and 2/ 3 ” and other types of installation with two kinds of fixed and PTZ while in the purchase of such security products to the attention of its argument , the following are the parameters for the purchase of the camera should be noted that some of the problems :

1 , sensor parameters

At present , the mainstream security cameras with CCD sensor element , in fact, a photoelectric conversion element . And compared to the previous CMOS sensor , CCD sensitivity is 3 to 10 multiples more than the CMOS , CCD chips thus can receive more light signals converted into electrical signals by the video processing circuit filter , amplified video signal output form . The stronger the received optical signal , the greater the amplitude of the video signal . Video signal is connected to a monitor or TV’s video input terminal can see video images. Improve image clarity simply is to improve the camera’s photographic capabilities.

2 , the parameters of the lens

Aperture : Aperture installed in the rear of the lens , the larger the aperture opening , the amount of light passing through the lens , the greater , the higher the sharpness of the image ; aperture opening as small , the amount of light passing through the lens smaller , more clarity of the image low . Usually F ( flux) to represent. F = focal length (f) / aperture . Technical specifications of the camera , we can often see 6mm/F1.4 such parameter , which indicates the lens focal length is 6mm, the luminous flux is 1.4 , then we can easily calculate the aperture of 4.29mm. In the case of the same focal length f , F value is smaller, the larger the aperture , the luminous flux reaching the CCD chip is larger , the lens the better.

FOV parameters: In engineering practice , we used horizontal field angle of the screen to reflect the shooting range . The larger the focal length f , the smaller the field of view , the photosensitive member formed on a screen smaller range ; the contrary, the smaller the focal length f , the field angle, the photosensitive member formed on the larger the screen .

Focal length (f) parameters: a focal length of the lens and the distance between the photosensitive member , by changing the focal length of the lens , the lens magnification can be changed , changing the size of the captured image . When the distance between the object and the lens is very far away , we can express the following formula : ≈ magnification lens focal length / object distance . Increase the focal length of the lens , magnification increases , you can narrow the vision , the picture smaller scope , the vision to see more clearly the details ; if the focal length of the lens to reduce the magnification is reduced, expanding the scope of the screen and can see the bigger scene .

Security cameras pixels and resolution than the computer’s video head to be high, but can not keep up professional digital camera or dv. security cameras just a single video capture device, it does not have the data storage function .

The installation of security cameras

Here I will introduce a security cameras installation method:

1 ) , to meet the monitoring requirements of the target field of view under the conditions of its installation height : Interior from the ground should not be less than 2.5m; outdoor ground should not be less than 3.5m.

2 ) , security cameras and supporting devices such as lenses, protective cover, bracket, wipers , etc., should be firmly installed , running should be flexible , should pay attention to anti-sabotage, and coordinate with the surrounding environment .

3 ) , in the strong electromagnetic interference environment , security cameras should be installed with the insulation isolation.

4 ) , the signal lines and power lines should be introduced separately , the exposed part of the hose protection, does not affect the PTZ rotation.

5 ) , the elevator car security cameras inside the car door should be installed in the top of the left or right , and can effectively monitor the elevator occupant compartment facial features.

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