As an important part of the infrared camera member, whose role is to focus the infrared camera CCD photographic light object, making the scene imaged on the CCD. Which may be ingested directly determines how much light CCD imaging clarity. A measure of how much light the lens uptake, the amount of light called the amount of light entering the lens is represented by F value (aperture). F value = f (focal length) / D (effective aperture of the lens), which is inversely proportional to diameter, and proportional to the distance focus. Under the same conditions as the focal length of the lens aperture, the smaller the F value, the greater the amount of light entering the lens. F value is more common lens 1.2, 1.4, is also a F1.0 lens. So in order to make low-light infrared camera to obtain the desired effect, you need to configure or the configuration phase for the F value smaller lens.