Two different uses: In the monitoring environment does not need subsidies in the use of infrared light, can be in a normal lens; infrared monitoring environment subsidies, to monitor ideal effect you have to use infrared lens, of course with ordinary infrared lens in the infrared subsidies can also see the picture, just the picture will become blurred. I believe that everybody have the experience. Secondly, the price difference between the two: Professional infrared lens prices are several times the ordinary lens, why? Because the use of infrared lens day and night are clear, the effect of good natural expensive. Two reasons why the performance and price is so different: Because the refractive index of glass is different for different wavelengths, the location of the focus will be different. Currently on the market can be done in the ordinary lens to the difference of 250nm or so wavelength light gathered on the same plane, that is, 430nm~650nm or 650nm~900nm range of light can focus on success, showing a clear image. This is why the ordinary lens during the day is clear, night vision blurred, or night vision clear, the reasons for the day blurred. Professional infrared lens with a special lens, can do the 430nm~900nm or even longer range of light are gathered on the same plane, so whether it is clear during the day or night vision. Due to the special nature of the lens material, so the cost is naturally high.