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FA Lens
We are a Chinese CCTV camera lens manufacturer. Our CCTV camera lens is made of FA lens, which has high optical power, easy installation, and convenience. It can be used for a variety of security applications.
Basic parameters of FA lens
The main parameters of the lens include focal length, resolution, working distance, depth of field, the field of view, distortion, etc.
Resolution
Refers to the number of black-and-white stripes that can be distinguished by the lens in unit millimeters at the image plane, which is affected by factors such as lens structure, material, processing accuracy, etc. The resolution of the following figure is 1/2d, where D is the line weight. The unit of resolution is lp/mm (line pair / mm). The resolution of the lens and camera affects the quality of final imaging.
Working distance
Generally refers to the distance from the front end of the lens to the measured object. Systems that are less than the minimum working distance and greater than the maximum working distance generally cannot image clearly.
Depth of field
Centered on the working distance when the lens is in the best focus, there is a range in front of and behind, within which the lens can image. Depth of field is affected by focal length and aperture: the shorter the focal length of the lens, the larger the range of depth of field. The smaller the aperture, the greater the depth of field.
Field of vision
The range that the image acquisition equipment can cover, that is, the size of the object plane corresponding to the image on the target surface.
Focal length
The concept of the focal length of the lens is slightly different from that of a convex lens because the lens is composed of multiple convex lenses. The focal length is the distance from the central point of the lens to the clear image formed on the glue plane. According to whether the focal length can be adjusted, it can be divided into a fixed focus lens and a zoom lens.
Distortion
The imaging distortion caused by the inherent characteristics of the convex lens cannot be eliminated. Aberrations only affect the geometry of the image, but not the clarity of the image.
Selection principle of FA lens
In the FA system, the main function of the lens is to place the imaging target on the photosensitive surface of the image sensor. The quality of the lens directly affects the overall performance of the FA system. Reasonable selection and installation of the lens are an important part of FA system design.
Step 1: Select the appropriate lens interface
The commonly used lens interface types include C port, CS port, f port, etc. when selecting a lens, you should first determine the lens interface type.
Step 2: Determine the focal length
Focal length is one of the most important parameters of a camera. Generally, whether the focal length can meet the requirements is considered first. The focal length of the lens can be calculated according to the overall size and working distance of the system and the ratio of the target size to the range to be measured.
Step 3: Determine the target size
The target size of the lens should be larger than that of the camera, otherwise, the amount of light entering may cause the loss of image information.
Step 4: Determine the aperture according to the lighting environment
According to the needs of the project, the aperture is determined according to the lighting environment by comprehensively considering the parameters such as resolution, distortion, and depth of field.
