Long range zoom camera always have defog features, including PTZ camera, EO/IR camera, widely used in defence and military, to see as far as possible. There are two main types of fog penetration technology:

1.Optical defog camera

Normal visible light cannot penetrate clouds and smoke, but near-infrared rays can penetrate a certain concentration of mist and smoke. Optical penetration of fog uses the principle that near-infrared rays can diffract tiny particles to achieve accurate and rapid focusing. The key to the technology is mainly in the lens and filter. By physical means, the principle of optical imaging is used to improve the picture clarity. The disadvantage is that only black and white monitoring images can be obtained.

2.Electric Defog Camera

Algorithmic fog penetration technology, also known as video image anti-reflection technology, generally refers to clearing the hazy image caused by fog, moisture and dust, emphasizing some interesting features in the image, and suppressing uninteresting features. Makes the quality of the image improved and the amount of information enhanced.

How to achieve defog features by ICR switch?

Many cameras use optical and electric defog together, for example, there are 3 filters in super long range zoom camera:

A: IR-cut filter

B: All pass filter (cut off just some Impurities）

C: Optical defog filter (pass only more than 750nm IR)

In color mode (with fog filter or without it), “A” in front of the sensor

In B&W mode and with fog filter OFF, “B” in front of the sensor

In B&W mode and with fog filter ON, “C” is in front of the sensor (OPTICAL DEFOG MODE)

So when in B&W mode, and digital defog NO, OPTICAL DEFOG active.

But for some normal range digital zoom cameras, it has only 2 filters:

A: IR-cut filter

C: Optical defog filter (pass only more than 750nm IR)

In colour mode (with fog filter or without it), “A” in front of the sensor

In B&W mode and with fog filter OFF, “C” in front of the sensor (OPTICAL DEFOG MODE)

In B&W mode and with fog filter ON, “C” in front of the sensor (OPTICAL DEFOG MODE)

So when in B&W mode, OPTICAL DEFOG active, no matter digital defog cameras ON or OFF.