The technology of zooming through optical lens structure is called optical zoom, which is opposite to digital zoom. Digital zoom is a method to obtain a larger scale picture by interpolating and enlarging some pictures.
Optical zoom is achieved by changing the position of lens, object and focus. When the image plane moves in the horizontal direction, the visual angle and focal length will change, and the farther scenery will become clearer, making people feel that the object is moving forward. As for the lens, the focal length of the lens is changed by changing the relative position of the lens in the zoom lens.
An important parameter in optical zoom is the zoom factor, which is the ratio of the maximum equivalent focal length to the minimum equivalent focal length of the lens. For example, if the minimum equivalent focal length of the lens is 18 and the maximum equivalent focal length is 55, then the zoom factor of the lens is 3.0555, which is called 3 times optical zoom for short. It should be noted that in the absence of technological innovation, the greater the optical zoom magnification of the lens, the lower the imaging effect. If we want to ensure good imaging effect, the lens group will become more complicated and its volume will be greatly increased.
The imaging effect of optical zoom is better than that of digital zoom, because optical zoom is that the photosensitive element really receives the light of the photographed object, and each pixel records the real parameters, while digital zoom actually only intercepts some parameters recorded by the pixel as frames, and then fills these frames with close color blocks through an algorithm, so it is even more unrealistic to smear false colors on the enlarged details of digital zoom photos.