The lens of a surveillance camera is generally divided into two types: fixed focus and zoom. We should choose a lens with a suitable focal length according to the scope and size of the scene to be monitored. General fixed focal length lenses mainly have focal lengths such as 2.8mm, 3.6mm, 4mm, 6mm, 8mm, 12mm, 16mm, 25mm, etc. The zoom lens is divided into manual zoom and electric zoom. Manual zoom, when we need to install, according to the monitoring range, manually adjust to the appropriate focus. The electric zoom can be remotely controlled to adjust the lens focal length by controlling the keyboard, DVR/NVR, client software, etc. at the back end. The focal lengths of common zoom lenses mainly include 2.8-12mm, 2.7-13.5mm, 3.5-11mm, 5-50mm, etc. For lenses with greater zoom capabilities, we can choose a cloud billiard ball machine. The built-in lenses have 10 times, 12 times, 18 times, 20 times, 22 times, 30 times, 60 times and other zoom capabilities. At the same time, these pan-tilt cameras generally support the pan-tilt up and down 90 degrees, left and right 360 degrees to choose, which can achieve all-round monitoring without dead ends.
