In long distance monitoring applications such as coastal defense or anti UAV, we often encounter such problems: if we need to detect UAVs, people, vehicles and ships  at 3 km, 10 km or 20 km, what kind of focal length zoom camera module should we use? This paper will give the answer.

Take our representative long range zoom camera module as an example. The focal length is 300 mm (42x zoom module), 540 mm (90x zoom module), 860 mm (86x zoom camera), 1200 mm (80x zoom camera). We assume that the imaging pixel is recognizable at 40 * 40, and we can refer to the following results.

The formula is very simple.

Let the object distance be “l”, the height of the object be “h”, and the focal length be “f”. according to the trigonometric function, we can get l = h * (pixel number* pixel size) / F

How many pixels are needed depends on the back-end recognition algorithm. If 20 * 20 pixels is used as the recognizable pixel, the detection distance is as follows.

So,excellent system must be the combination of software and hardware. We welcome powerful algorithm partners to cooperate to create great long range monitoring camera products together.