Lens selection and setting shall meet the following requirements (Fig. 6.0.2)


1. The size of the lens image plane should match the size of the camera target plane, and the lens interface should match the camera interface.


2. The fixed focus lens can be selected for the camera used for fixed target monitoring, and the long focus lens can be selected when the distance between the monitoring target and the camera is large; when the viewing angle or field of view of the monitoring target needs to be changed, the long focus lens can be selected


Zoom lens should be selected; wide angle lens can be selected when the monitoring target is close to the camera and the viewing angle is large.


3. The focal length of the lens is determined according to the size of the field of view and the distance between the lens and the monitoring target, which can refer to the code for engineering design of video security monitoring system (GB 50395-2007)


Calculate according to the following formula:


F?? a?? L / h equation 6.0.2


Where: F -- focal length (mm);


A-image field height / width (mm);


L -- distance from lens to monitoring target (mm);


H -- height / width of field of view (mm).


4. The manual variable aperture lens should be selected when the illuminance of monitoring target environment is constant or small.


5. If the illumination range of the remote control camera is more than 100 times higher than that of the day and night, the electric camera shall be used.


6. The zoom lens should meet the requirements of maximum distance close-up and maximum field of view angle observation, and the zoom lens with automatic aperture and automatic focusing function should be selected. The response speed of zoom lens should be adapted to the moving speed of moving target and pan tilt.

7. When the camera needs to be installed covertly, covert measures should be taken, and the lens should be small hole lens or prism lens.