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The definitions of megapixel lenses are different for each lens brand. Take a 1.5-megapixel lens as an example. Some Japanese brand definitions: From the center of the screen to the periphery of the screen, 70% of the screen area can reach 1.5 million pixels. Other parts Can reach 1 million pixels, such a lens is called a 1.5-megapixel lens; some Japanese brand definition: 65% of the screen area can reach 1.5 million pixels, the other part can be to 1 million pixels is called a 1.5 million-pixel lens; also Some Japanese brand definitions: At least 95% of the screen area can reach 1.5 million pixels, and other parts can only be 1.5 million pixels to 1 million pixels. The definition of domestic brands is even worse, the general is: the center part can reach 1.5 million pixels, is called a 1.5 million-pixel lens, and around what the definition, can not reach 1 million pixels are difficult to say. In general, megapixel lenses do not yet have a unified specification, and they are still in a good and bad situation with respect to the effect of definition.
The lens coating. There are many kinds of coating processes, and each lens manufacturer's coating process also has its own characteristics. The coating plays a significant role in color reproduction and processing polarization color cast. At present, in the domestic surveillance market, the processing of color reproduction has progressed, basically satisfying the users, but the polarizing color cast, especially the processing of glare ghosts, is also quite different from the lens used in foreign markets.
The megapixel lens technology's 'light transmittance' directly affects the clarity of the lens, which is an indispensable and important condition for high-definition image quality. 'Light transmittance' refers to the light transmission capability of the lens lens. The main decisive factor is the coating technology. At present, the highest transmittance coating in the industry belongs to the SMC coating of Japan's Pentax lens, and the transmittance reaches the highest 0.998 in the industry, laying a solid foundation for the long-term development of high-definition lenses. In addition, the higher the light transmittance, the greater the amount of light transmitted, and the lower the illumination requirements, especially at night monitoring conditions, the level of illumination is a determinant of the quality of a night shot.
In the domestic market, the material of the lens is also necessary to mention. The lens material is generally divided into glass lenses, composite lenses and resin lenses, and the monitoring lens must use glass lenses. Because resin and composite lenses are prone to aging and even deformation under high temperature and exposure conditions, they seriously affect the image quality and lens quality. Due to the fact that manufacturers of high-definition lenses are currently far less sophisticated than analog lens manufacturers, they have not yet found lenses for resin and composite materials used in high-definition lenses.
An important factor affecting the sharpness of the lens, especially the sharpness of the edges, is the aspheric technique. Aspherical lenses can effectively increase the amount of light transmitted by the lens edge, effectively correcting the aberration blur caused by spherical lenses. In practical applications, few manufacturers use aspherical lenses in small-focus lenses. Although a large number of aspherical lenses are rendered in publicity, they are rarely used. Through the test, it can be easily seen that the lens 8 with slight blurring on the edge of the imaging picture is not an aspheric lens, and the lens of most Japanese brands is the same. This phenomenon is mainly caused by cost reasons. High-grade glass aspherical lenses use the grinding process at the edge of the glass lens. The common method is to coat the surface of the glass sphere to make it an aspherical surface. Both of these aspherical processes are to increase the cost, especially the former. Therefore, aspheric lenses are rarely seen in batch applications, especially in products with less stringent performance requirements. In the megapixel lens of electric zooming, since the lens itself is more expensive and the required effect is higher, the aspheric surface is a big selling point and a necessary technical indicator.
The concept of depth of field is a megapixel lens, especially when the future megapixel lens dominates the market.
At present, it is not possible to see the depth of field parameter in the parameters of the camera, nor do we know how much the actual depth of field is. However, after imaging, we can clearly see which lens has a larger depth of field. High-definition cameras require a very clear picture in the monitoring, and the entire picture can be clearly presented, even after zooming in, the distant scenery can be seen clearly. At this time, the camera needs a good depth of field, and the greater the depth of field, the greater the range of distance that can be clearly seen on the image after the imaging. After the image is enlarged, you can see the distant scenery more clearly, such as road monitoring. , You can see the license plate number and so on through the screenshot. Currently, there are only one or two manufacturers that can make the depth of field of the HD lens very large. Moreover, on the basis of making full use of the large depth of field, it is possible to maintain the clarity of the lens during zooming. Need to refocus. Some of the old Japanese manufacturers are also gradually applying the new technology in television lenses to surveillance cameras.
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