Dongzheng optical not only have a rich lenses products line, but also can meet a variety of uses such as ultra high definition, night vision, through fog, high and low temperature, auto focus, etc., and according to customer’s needs we offer customized and developed service , to satisfy special demands from clients.
Characteristics and classification of industrial lenses
Optical lens is generally called camera lens or photographic lens, or lens for short, the function of lens is optical imaging. The lens is an important component in the machine vision system, which plays a key role in imaging quality. It affects several of the most important indicators of imaging quality, including resolution, contrast, depth of field, and various aberration. There are many kinds of lenses, and also the quality difference is very large, but the average user often pays insufficient attention to the choice of lens when designing the system, resulting in the failure to get the ideal image, and even the failure of system development.
The industrial lens is equivalent to the crystalline lens of the human eye. If there is no crystalline lens, the human eye cannot see any objects; if there is no lens, then the image output by the camera will be a white piece with no clear image output. The principle is consistent the same as our home cameras and photo cameras. When the muscles of the human eye cannot stretch the crystalline lens to the normal position, which is what people often call myopia, the scene in front of the eyes becomes blurred.There is a similar phenomenon between the camera and the lens. When the image becomes unclear, you can adjust the back focus of the camera and change the distance between the CCD chip and the reference surface of the industrial lens (equivalent to adjusting the position of the human crystalline eye lens) to make blurred images clear.It can be seen that the role of the lens in the CCTV system is very important.Engineering designers and construction personnel work with the lens very frequently: the designer must calculate the focal length of the lens according to the object distance and imaging size. The construction personnel often carry out on-site debugging, part of which is to adjust the lens to the best state.
1. Installation dimensions and interfaces of industrial lenses
All camera lenses are threaded. There are two industry standards for CCD camera lenses, namely C mount and CS mount. Both thread parts are the same, but the distance between the two from the lens to the photosensitive surface is different.
C mount: The distance from the lens mounting reference plane to the focal point is 17.526mm.
C / S mount: For special C mounting, first remove the gasket on the front of the camera and then install the lens. The distance from the lens installation reference plane to the focal point is 12.5mm. If you want to install a C mount lens to a C S mount camera, you need to install a 5mm thick ring.
Classification and characteristics of civilian lenses
Lenses are generally classified according to focal length:
Fisheye lens; macro lens; wide-angle lens; standard lens; telephoto lens; super telephoto lens; zoom lens, etc .;
Standard lens: It can be used for shooting landscapes and people, between wide angle and telephoto
Telephoto lens: Take close-up shots of distant people and distant objects, such as sports games
Wide-angle lens: shooting landscapes and large scenes with infinite focal length
Fisheye lens: 180 degree angle of view, large distortion, special purpose
Macro lens: Shoot small objects at close range, such as small ants, etc.
Super telephoto lens: can shoot the moon and stars;
Zoom lens: a lens whose focal length can be changed according to the subject of the shooting, and it can shoot sports effects.
The difference between industrial lens and civilian lens
1. Different clarity
The resolution of the lens in the center of the imaging plane is the highest, and at the edge is weak. The common lens can basically meet the sharpness at the center resolution, and the sharpness of the edge is reduced a lot. The overall sharpness can meet the requirements of 440,000 pixels of the ordinary camera. There are three key factors that determine the sharpness of the lens.
(1) Lens element material and purity. The less impurities in the element, the less interference light it produces, and the higher the picture clarity;
(2) Lens element grinding accuracy. The grinding accuracy of the lens is determined by the grinding equipment. At present, there are several differences between domestic lenses and foreign lenses.
(3) The coating accuracy of the lens. The precise control of the coating process is also one of the determinants of lens clarity. In addition, the megapixel lens uses aspherical lenses, which can reduce aberrations, and achieves a compact design while improving clarity compared to ordinary lenses.Through special optical design technology, the image quality from the center of the image to the peripheral part achieves high-resolution and high-contrast images, which improves the resolution by more than 2.5 times compared with traditional lenses, even when the image is cut or enlarged, it still can ensure high image quality.
2. Different spectral transmission capabilities
The spectral transmission capability of the lens also contributes to the improvement of picture clarity. The transmission of wide frequency light will greatly increase the amount of light received by the camera target surface. It can enhance the contrast and brightness of the picture and show more details on the picture.
3. Different spectral correction capabilities
The wide-spectrum transmission capability alone is not enough for high-definition imaging. When the spectral correction capability of the lens is insufficient, some wavelengths of light cannot be accurately imaged on the target surface of the camera, resulting in a virtual image. Ordinary lenses of this technology cannot be realized with a coating.