Network camera spring defense technology: lens development and selection

    With the popularity of megapixel cameras in recent years, the demand for megapixel lenses has also increased accordingly. In addition to the traditional transportation field, other emerging industry applications such as urban monitoring also list high-definition systems as the first choice. Faced with a wide range of products from major security manufacturers, how can users choose the lens that suits them?

    The development of lens technology

    From lenses to movements, before domestic movement manufacturers achieved research and development results, most of the movement market was controlled by Japan's Sony, Hitachi, Sanyo and South Korea's LG, Samsung, CNB, etc.; the lens, which accounts for half of the movement cost, is monopolized by Japanese companies such as Nagano, Tamron, and Canon; key components such as CCD and CMOS are monopolized by SONY or multinational groups from other countries such as the United States, while core technologies such as high-end autofocus algorithms and high-end night vision fill light are still blank in China. As far as the movement is concerned, the key technologies are in three aspects: lens, autofocus, and imaging devices. Faced with such a situation, many powerful domestic excellent national security companies insist on continuous innovation, and have achieved complete independent research and development and independent completion from the main control board, lens, optical design and production.

    Automatic zoom lens

    In terms of automatic zoom focus lenses, Japan's Tamron, Nagano and Canon are still the main manufacturers in the world. In addition, a lens manufacturer in Shenzhen has gradually caught up and made major technological breakthroughs through its own design and production. The manufacturer's lens technology, such as automatic aperture, IR-CUT switching, multi-layer coating, aspherical surface, low dispersion, large aperture (aperture value F1.6-F3.2), etc., has shown obvious overall advantages, and has the ability to develop and produce full-featured, cost-effective, small-volume zoom lenses.

    Domestic optical technology has made great progress. Take a domestic lens manufacturer in Shenzhen as an example. Its optical technology has distinct characteristics. It uses high-refractive index, low-dispersion materials and multiple aspherical lenses to effectively suppress high-grade spherical aberration and chromatic aberration, and ensure high resolution and high contrast in the center and peripheral axial and normal directions. The field of view angle reaches 60°~2.7°.

   Photoelectric image processing main control board

    At present, domestic movement solutions have not yet reached a high level of independent research and development and production, and are still highly dependent on major foreign parts and components. However, domestic manufacturers can develop movement solutions that meet the needs of domestic security companies by selecting different solutions. For example, a domestic movement manufacturer mainly uses SONY and SHARP solutions; in order to meet the needs of different customers and industries, it has developed three control board solutions in different fields: EFFIO-E (economic), EFFIO-S (standard), and EFFIO-P (professional).   

    Selection of HD lens

    Compared with ordinary lenses, megapixel lenses have incomparable characteristics and advantages, but what issues should we pay attention to when choosing megapixel lenses?

   Clarity Correspondence

    When high-definition cameras first entered the market, their resolution was usually around 1 million pixels, and users often felt that megapixel lenses were too expensive. However, high-definition cameras equipped with standard-definition lenses have good results, and their resolution has been greatly improved compared to standard-definition systems. However, many systems will have blurred images, especially when the center of the image is clear but the edges are blurred, and debugging for this cannot achieve satisfactory results. As 2 million, 3 million, and 5 million cameras entered the market, users gradually became familiar with megapixel lenses and began to rationally choose the appropriate lens based on the camera.

    Megapixel lenses are divided into 1.3 million pixels, 2 million pixels, and 3 million pixels according to the clarity. High-end products have 5 million pixels, and some excellent manufacturers have achieved 10 million pixels. So when choosing a lens, you should choose a lens product with the same or higher pixels according to the highest resolution of the camera. For example, a 2 million pixel snapshot CCD camera commonly used in traffic should choose a 25mm or 35mm 2 million pixel product according to the actual application environment. The clarity of the current common electric zoom lens is generally 1.3 million pixels, and the demand for telephoto and high-definition lenses is diverse. For high-definition cameras above 2 million, you should choose a high-definition electric zoom lens that corresponds to its clarity, so products above 2 million are the first choice. Of course, higher-definition products should choose higher-pixel lenses, such as 3 million and 5 million products.

   Select products with matching functions according to camera applications

    In some projects, cameras need to be used with infrared fill lights. In this way, lenses with IR functions should be used. This way, brighter images can be obtained at night, and the problem of out-of-focus at night can be reduced. For more demanding environments, such as using laser lights to monitor long-distance targets, it is necessary to ensure that the non-visible light wavelength can still reach a transmittance of more than 60% at 900um.

    Solve the delay problem with auto-focus lens

    At present, most high-definition cameras on the market use IP output, that is, the encoding is completed inside the camera. After being transmitted through the network, it needs to be decoded in the monitoring center before it can be displayed on the screen. As we all know, the camera will cause delays during the encoding process. Similarly, network transmission will also cause delays, and the decoding process of the monitoring center will also cause delays. Therefore, the more devices it passes through and the more times it is forwarded, the longer the delay will be. The superposition of these delays will seriously affect the operation of the monitoring personnel. For fixed-focus products, this part of the delay has a relatively small impact. For systems using electric zoom lenses, it brings embarrassment to use. On the one hand, it is a high-definition system, and on the other hand, due to the delay superposition mentioned above, the picture will always be out of focus, or the focusing time is too long, and the target cannot be captured quickly. In this case, you should choose a product with automatic focus function. By using an automatic focusing lens, the focusing process is automatically completed at the front end, so that the picture transmitted back to the center is always clear, which can bring the following benefits to the HD system: 1. It reduces the operator's focusing operation on the lens and extends the service life of the motor; 2. Because the picture is always clear, the camera can have higher efficiency and higher compression ratio when encoding, reducing the resource occupation of transmission and storage; 3. It shortens the target capture time, allowing monitoring personnel to browse more pictures per unit time, thereby improving the effectiveness of the monitoring system.

    With the popularity of high-definition cameras, more and more systems require the access of high-definition lenses. Major lens manufacturers have launched high-definition products with different focal lengths, providing users with more choices. With the application of ED lenses, autofocus and other functions in high-definition lenses, the difference between high-definition electric zoom lenses and standard-definition products is getting smaller and smaller. The future trend will be a great integration of products. High-definition products will gradually replace existing standard-definition products and become the mainstream of the market.