How to identify good and poor quality of security lens?
Lens is one of most important component for CCTV system, it's the essential component to consist the CCD image device. There are plenty of manufacturers that produce the various types of lens and models, also the improved features special lens continue launched. Now we can find the non-spherical lens in the market, it's belong to this innovation products. It breaks through the regulates of the CCTV industry, and innovate the traditional manufacturing process.
Due to there are too much security lens, how to select the correct lens for security dealer and integrator or end user, and meet the requirements ? We herein provide below information to help you on this issue.
Lens Housing Material
Most of well-known brands adopt the special high-strength plastic as the lens housing material to decrease the weight of lens, reduce the efforts of outdoor temperature thermal expansion and contraction phenomenon to insure the accurate and keep the position of lens. Making the high-strength plastic shell mold are expensive, with complex of processing features. And metal housing are easy to be counterfeit.
Lens Coating
Lens coating process have a direct impact on the quality of image. If use human eyes can see a thickness of coating violet color, that means the lens coating height is moderate can reach the best translucent effect. Lens coating not only need use the advanced equipment, but also master the coating time. The coating color can be change to different color in a second, with the strict requirement of time and experience for the operators. The normal depth of coating is 540um ± 20, coating too deep or thick can not achieve the best translucent effect. Due to the difference of technology, after some times of wipe, the lens coating may disappear from the security lens. Without lens coating, the lens will effect the usage of lens.
Lens Material
The material choosing for lens is a major factor when processing the lens. lens glass too hard or soft or contain too much lead may effect the lens can not achieve the best effect.
Lens zoom focus feeling
Good quality lens with a little of resistance when zoom and focus the lens, adjust to the appropriate position, and the position is not easy to deviate. The poor quality one likely to loose. There are Japanese made special mineral oil in the true good quality lens, it is not easy to move inside, and increase the lubricating ability.
Non-spherical day & night lens
Non-spherical lens with the advantage of adjust the infrared images and ensure the quality of images. Due to the length for infrared ray and visibly ray are different, ray go through the spherical refract and focus, the focal point is not in the same point. This caused images a little blurry when in the environment of shortage of visible light and infrared light is strong.
Light through rate ( F)
Typically the F value more small, the more light will be refract in, to improve the quality of image. F value is one of most important factor between good quality and poor quality lens. F value is not unlimited small, for zoom lens to achieve a large zoom range and also to maintain good flux is a very difficult thing. Using the human eye to compare different brands with same type lens, the smaller of F value, the better of the lens.