监控的焦距怎么选

How to choose the focal length of monitoring

什么是焦距

What is focal length

焦距：指平行光入射时从透镜光心到光聚集之焦点的距离。镜头焦距的长短决定着拍摄的成像大小、视场角大小、景深大小和画面的透视强弱。

Focal length: refers to the distance from the optical center of the lens to the focal point of light gathering when parallel light is incident. The length of lens focal length determines the image size, field angle, depth of field and perspective of the picture.

监控摄像机镜头的类型：

Type of camera lens:

监控摄像机的镜头焦距正常用到的有2.8毫米，4毫米，6毫米，8毫米，12毫米。可以根据被监控对象来选择监控摄像机的镜头，一般镜头焦距越小，看到的角度范围越大，但监控到的距离也越短。

The normal focal length of the camera is 2.8mm, 4mm, 6mm, 8mm and 12mm. The camera lens can be selected according to the monitored object. Generally, the smaller the lens focal length is, the larger the viewing angle range is, but the shorter the monitoring distance is.

所以2.8毫米镜头适合照楼道和电梯这些狭小环境的点位，4毫米照房间，6毫米适合照走廊或单元门，8毫米适合车间或走廊，12毫米适合照狭长道路。

So the 2.8mm lens is suitable for taking pictures of the narrow environment such as the corridor and elevator, the 4mm lens is suitable for taking pictures of the room, the 6mm lens is suitable for taking pictures of the corridor or unit door, the 8mm lens is suitable for taking pictures of the workshop or corridor, and the 12mm lens is suitable for taking pictures of the narrow and long road.

（图片来源于网络）

(picture from Internet)

监控的焦距怎么选呢

How to choose the focal length of monitoring

不同的镜头焦距的广角镜头强烈推荐的监控器间距：

Recommended monitor spacing for wide-angle lenses with different lens focal lengths:

▶ 2.8mm的长焦镜头可以 用在储藏间等狭小室内空间设计的监控地理环境中，最好是监控间隔3m以内。

▶  The 2.8mm long focal lens can be used in the monitoring geographical environment designed for the storage room and other narrow indoor space, preferably within 3M of the monitoring interval.

▶ 4mm的广角镜头能够 用在小铺面或是家中等室内空气中，最好监控器间距3-5m。

▶  4mm wide-angle lens can be used in small pavement or medium indoor air. The best distance between monitors is 3-5M.

▶ 6mm的广角镜头能够 用在小铺面或是大门口等情景下，最好监控器间距5-10m。

▶  The wide-angle lens of 6mm can be used in small shop or gate and other situations, and the best monitor spacing is 5-10m.

▶ 8mm的广角镜头能够 用在户外的路面、巷子等情景下，最好监控器间距10-20m。

▶  8mm wide-angle lens can be used in outdoor road, lane and other situations. The best distance between monitors is 10-20m.

▶ 12mm的广角镜头主能够 用于监控器特殊部位，例如某些特殊的入口处等，最好监控器间距20-30m。

▶  The 12mm wide-angle lens can be used for special parts of the monitor, such as some special entrances, etc. the best distance between monitors is 20-30m.

不一样的机器设备相匹配的视场角不一样，因此实际可用的间距也会大不一样，必须以机器设备的具体主要参数为标准。

Different machines and equipment match with different field angles, so the actual available spacing will be different, and the specific main parameters of the machine and equipment must be taken as the standard.