How to choose high-definition surveillance camera

1, monitor camera definition selection. The definition of surveillance cameras is generally 420 lines for civilian use, and 480 lines are mostly 520 lines, 600 lines and 700 lines. The more lines, the clearer. The number of lines represents the sharpness of the camera, that is, the number of lines scanned horizontally by the display. Generally, more than 600 lines represent HD cameras.

There are many fake labels on the market, some of which are 700 lines, but actually there are only 500 lines, which is very different. We often take the actual test as the standard, and we can see the clarity with an ordinary TV.

2. Distinguish the appearance of the surveillance camera. Different shapes can be divided into hemispherical camera and gun camera. The hemispherical naming has the advantages of small size and beautiful appearance, and is suitable for installation in indoor, office, hotel corridor, elevator, corridor and other places with good concealment.

Hemisphere has a small focal length and is suitable for shooting nearby objects. Gun cameras are suitable for installation in all places, and there is no specific difference from hemispherical cameras. Other special-shaped cameras (such as flying butterflies, smoke sensors, pinholes and smoke sensors) are suitable for indoor places with special requirements.

3. Monitor the differences between camera lenses. Generally, 3.6MM and 4MM are wide-angle lenses, that is, the shooting range is relatively wide, that is, the horizontal range is relatively large, but people will become smaller when the distance is opened. Of course, things will also become smaller with distance, which is suitable for shops or family doors, that is, when the subject is 3-5 meters away.

4. Selection of monitoring camera interface. At present, the cameras on the market are generally BNC connectors, but recently the network interface and RJ45 interface are popular, which are ultra-high-definition cameras, but the price is higher.

Extended data:

Related knowledge:

1. Monitor camera lens

Focal length: The focal length of the surveillance camera refers to the distance between the lens and the photosensitive element. The magnification of a lens is approximately equal to the ratio of focal length to object distance. That is to say, with the increase of the focal length of the surveillance camera, the magnification increases, which can narrow the close shot and make the details of the distant view clearer, and vice versa.

Classification: surveillance cameras can be classified according to the size or aperture of the lens, and different types of surveillance cameras can be selected as needed when purchasing.

2. Photosensitive ability

In order to improve the clarity of the images collected by the surveillance camera, it is necessary to improve the photosensitive ability of the camera. The photosensitive element of CCD is 3 to 10 times that of CMOS, which can get optical signals better, then convert them into electrical signals, and finally process them into video signals for output or storage.

3. Control of monitoring camera

In order to maximize the observation range of the surveillance camera, the surveillance camera must be able to rotate. The method is to install a fixed monitoring camera by rotating the pan/tilt.

In addition, it must be able to achieve electric zoom and zoom. This requires that the camera in the surveillance camera can realize automatic zoom quickly and accurately. This has also become a standard for judging the quality of surveillance cameras.

4. Monitor the image transmission of the camera

The most widely used transmission mode is through the cooperation of analog cameras, digital hard disk video recorders and computer network systems.

5. Definition of terms related to surveillance cameras

(1) Resolution: The resolution of the monitoring camera in use refers to the number of points displayed in the horizontal and vertical directions of the screen. The higher the resolution, the clearer the image.

(2) Definition: The definition of the monitoring camera is expressed by lines, which are divided into horizontal lines and vertical lines. The more lines, the higher the definition and the clearer the image.

(3) Signal-to-noise ratio: refers to the ratio of signal electrical frequency to clutter electrical frequency in the surveillance camera, usually expressed in DB. The higher the signal-to-noise ratio, the better the surveillance camera and the better the image signal, that is, the clearer the image.

(4) White balance: White balance is an index to describe the white accuracy after the three primary colors of red, green and blue are mixed in the display. By adjusting the white balance of the surveillance camera, the color quality of the picture can be improved.

(5) Backlight compensation: When the camera shoots in a backlight environment, a black image will appear on the screen. This is a disadvantage for surveillance cameras that work 24 hours a day, so backlight compensation is needed. Using the backlight compensation function, if the camera detects that the video level of a certain area of the captured image is relatively low, it will increase the amplitude of the output video signal and make the image clear.

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