Buy surveillance cameras to see which targets
Aperture: the aperture is mounted on the back of the lens. The larger the aperture, the greater the light amount of the lens, the higher the definition of the image. The smaller the aperture, the smaller the light in the lens, and the lower the clarity of the image. F (light flux) is usually expressed. F = focal length (F)/light aperture. In the technical index of the camera, we can often see 6 mm/allows such argument, it said the focal length of the lens is 6 mm, luminous flux is 1.4, then we can easily calculate the clear aperture of 4.29 mm. In the case of the same focal length f, the smaller f value, the larger the aperture, the greater the light flux of the CCD chip, the better the lens.
Focal length (f) parameters: the focal length is the distance between the lens and the sensor. By changing the focal length of the lens, it can change the magnification of the lens and change the image size. When the object is far away from the lens, we can use the formula below: the zoom of the lens is approximately the focal length/object distance. Increase the focal length of the lens, enlarge the magnification, and bring the vision closer, the scope of the picture is small, the details of the vision can be seen more clearly. If you reduce the focal length of the lens, the magnification is reduced, the scope of the image expands, and you can see the larger scene.
At present, the sensor of the mainstream surveillance camera adopts the CCD element, which is actually the photoelectric conversion element. Compared with the previous CMOS sensor, CCD sensitivity is from 3 to 10 times that of the CMOS, CCD chip can receive more light signals, converted to electrical signals, after the video processing circuit filter, enlarge formation, video signal output. The stronger the light signal, the bigger the video signal. The video signal is connected to the video input end of the monitor or TV set to see the video image. The basic idea of improving the image is to improve the camera's light-sensitive ability.
