How to choose the focal length of surveillance camera?

Generally speaking, 2.8mm/4mm lens is used in scenes with small object distance and large field of vision (such as small rooms); 6~ 12mm lens is used in scenes with small visual field and long object distance (such as corridors and passages); 6mm/8mm lens is used in scenes with large object distance and large field of vision (such as outdoor places).

For example, elevator 2.8mm lens, room 2.8mm/4mm lens, lobby 4mm lens, channel 6mm/8mm/ 12mm lens, warehouse 6mm/8mm/ 12mm lens, outdoor 6mm/8mm lens, fence 8mm/ 12mm lens.

The lens perspective corresponds to the place of use.

A wide-angle lens is a lens with a particularly wide viewing angle, from 80 to 1 10. However, the ultra-wide-angle lens has a viewing angle of more than 90 and a wider observation range, but it is not as strongly distorted as the fisheye lens.

The standard lens has a viewing angle of about 45 ~ 50, which is the most basic photographic lens of all lenses. Its focal length is roughly equal to the diagonal length of the shot picture, so its picture effect is very similar to human visual effect.

The viewing angle is within 20 degrees, and the focal length ranges from tens of millimeters to hundreds of millimeters. It belongs to telephoto lens and is used for remote monitoring. Pinhole lenses are about a few millimeters in diameter, which can be installed in hidden places for hidden observation, and are mostly installed on ceilings or walls.

In addition, the focal length of the zoom lens can be changed from wide angle to telephoto, which is used in areas with large depth of field and wide viewing angle range; Usually electric, it can be used for wide-angle, standard or telephoto lenses.