Lens has two meanings in film and television. One refers to the optical components used by movie cameras and projectors to generate images, which are composed of multiple lenses. Various lenses have different appearance characteristics. Their use in photographic appearance constitutes an optical performance wrist; the other refers to a continuous picture taken from power-on to power-off, or one of two splice points The clip in between is also called a ytterbium. This two meaning are two completely different concepts. In order to distinguish the difference between the two, one meaning is often referred to as an optical lens and the other is referred to as a lens picture.
The main function of the lens is to collect the reflected light of the illuminated object and focus it on the CCD. The image projected on the CCD is inverted. The camera circuit has the function of inverting it. The imaging principle is opposite to the human eye.
The classification of the lens can be classified according to the focal length, the digital size of the focal length, the aperture division and the lens telescopic adjustment.
(1) According to the focal length, there are fixed focal length type, telescopic type, automatic iris or manual iris.
(2) According to the number of focal lengths, there are standard lens, wide-angle lens and telescope number one type.
(3) According to the aperture classification, there are fixed aperture type (fixed iris), manual aperture type (manual iris), auto aperture type (auto iris) and other types.
(4) According to the adjustment methods of lens expansion and contraction, there are types such as electric retractable lens and manual retractable lens.
2.Elements that determine lens quality
(1) The number of lenses used: multi-type lens combination can increase color shift and improve focus, but will increase light transmittance.
(2) Lens transmittance: good lenses have good light transmittance and are expensive, and poor lenses will hinder the passage of light.
(3) Coating and grinding: Lens coating and grinding technology affect the lens quality.
(4) Mechanical installation: The precision of the external mechanical structure of the lens affects the accurate plating and reliability of the lens movement. The poor quality mechanical structure will cause adjustment errors and inconsistencies.
In a monitoring environment that does not require infrared light subsidies, an ordinary lens can be used; in a monitoring environment with infrared light supplementary light, an infrared lens is necessary to have a more ideal imaging effect; of course, a common lens is used in infrared light supplementation You can also see the picture below, but the picture will become blurred, I believe everyone understands it well.
Secondly, the prices of the two are different:
The price of a professional infrared lens is several times that of a normal lens. Due to the infrared lens, the imaging at night and morning is relatively clear, and the effect is natural and expensive.
The reason why the two functions and prices are so different:
Due to the different refractive index of glass for different wavelengths of light, the position of the focus point will be different. At present, ordinary lenses on the market can achieve the convergence of light with a wavelength of about 250nm to the same three-dimensional, that is, 430~650nm or 650~ The light in the range of 900nm can be focused successfully, presenting a clear image, which is why the daylight of the ordinary lens is clear and the night vision is blurred, and perhaps the night vision tone is clear and the reason of the day is blurred.
The professional infrared lens uses special lenses, which can focus the light of 430~900nm or even longer wavelength range on the same stereo, so it is clear whether it is daytime imaging or night vision. Duformation, te to the special lens inhe cost is naturally high.