How to convert the magnification of optical zoom in digital camera into magnification?

Optical zoom relies on optical lens structure to achieve zoom. The zoom mode is similar to that of a 35mm camera, that is, the scene to be shot is enlarged and reduced by the movement of the camera lens. The larger the optical zoom factor, the farther the scene can be shot. Optical zoom, like traditional camera design, depends on the focal length of the lens, so the resolution and image quality will not change. In other words, optical zoom can support the image subject to add more pixels after imaging, so that the subject is not only larger, but also relatively clearer. Usually the optical zoom is large and suitable for telephoto shooting. At present, the optical zoom multiples of digital cameras are mostly between 2 and 5 times, and some digital cameras have an optical zoom effect of 10 times. Basically, if the position of the subject remains unchanged, the focal length of the lens will be proportional to the magnification of the object: magnification = image size/subject size optical zoom. For example, the lens focal length of Sony Cybershot DSC-F828 digital camera is equivalent to the focal length of 28 ~ 200mm of 35mm camera, so we say that it is 7 times optical zoom, that is to say, the original lens focal length is 28mm, and the maximum lens focal length can be adjusted to 200mm after the lens system is telescopic. At the same shooting distance, the shot scene can be enlarged by 7 times. Tips on how to see the optical zoom multiple from the camera body ★ We can calculate the optical zoom multiple from the zoom range (focal length) of the lens. For example, the lens of Sony Cybershot DSC-F828 digital camera is clearly marked with "7. 1-5 1", which means that the zoom range (focal length) is from 7. 1 mm to 5 1 mm, then the optical zoom multiple can be calculated as 5/kloc-0. ★ Many digital cameras also directly mark the optical zoom magnification on the body or lens. For example, the top of the Sony Cybershot DSC-F828 digital camera is clearly marked with "7x optical zoom" (see figure 1). At present, the optical zoom multiple of digital cameras is mostly between 2 and 5 times, which can zoom objects beyond 10 meter to 5-3 meters; There are also some digital cameras whose optical zoom effect is 10 times. The optical zoom factor of home camcorder is 10 ~22 times, and it can clearly shoot things 70 meters away. Using a magnifying glass can increase the optical zoom factor of the camera. If the optical zoom factor is not enough, we can add a zoom lens in front of the lens. The calculation method is as follows: A 2-fold zoom lens is set on a 4-fold optical zoom digital camera, and then the optical zoom multiple of this digital camera will be changed from the original 1, 2,3,4 times to 2,4,6 times and 8 times, that is, it is obtained by multiplying the zoom lens multiple and the optical zoom multiple. There are pictures in resources: resources:

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