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Shenzhen Changhong Microelectronics Co.,Ltd

Surveillance Camera Common Lens Knowledge

1, the type of lens (according to the application category)

Wide-angle lens: The angle of view is more than 90 degrees, and the image is deformed near the larger observation range.

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, the focal length can be changed from wide angle to telephoto, and the longer the focal length, the larger the imaging. The focal length can be adjusted as needed to enlarge or reduce the image of the subject. The commonly used zoom lens is a six-fold, ten-sale zoom.

Pinhole lens: used for concealed observation, often installed in places such as ceilings or walls.

2, the aperture of the lens

In order to control the amount of light flux passing through the lens, an aperture is provided at the rear of the lens. Assuming that the effective aperture of the aperture is d, due to the relationship of light refraction, the effective effective aperture of the mirror light is d, which is larger than d, and the ratio of d to focal length f is defined as the relative aperture a, ie, a=d/f, the relative of the lens. The aperture determines the illuminance of the image, and the illuminance of the image and the reciprocal of the relative aperture of the lens represent the size of the lens aperture. The smaller the f value, the larger the aperture and the greater the luminous flux reaching the ccd chip. Therefore, in the case where the focal length f is the same, the smaller the f value, the better the lens.

There is aperture: the size of the lens aperture can be adjusted. According to the changes in the environment, the size of the aperture should be adjusted accordingly. The size of the aperture can be adjusted manually or automatically, and the aperture is manually adjusted manually, called the manual aperture. The lens comes with a micro motor that automatically adjusts the aperture, called the auto iris.

No aperture: the aperture is fixed, and the amount of light passing through it is fixed. It is mainly used when the light source is constant or the camera has its own electronic shutter.

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