Is the optical zoom of mobile phone really effective or a gimmick?

Optical zoom is achieved by changing the positions of lens, object and focus. When the image plane moves horizontally, the visual angle and focal length will change, and the farther scenery will become clearer, making people feel like the object is moving forward. Optical zoom is generally achieved by changing the focal length of the lens. The focal length of the zoom lens is changed by changing the relative position of each lens.

Because the lens needs to be moved, it needs to occupy more space to realize optical zoom, but the space of mobile phone is very limited at present, and it is difficult to realize multiple optical zooming of mobile phone. Huawei's P30 pro is used as a periscope camera. Using the reflection principle of prism, the movement of the lens is changed from vertical direction to horizontal direction, which greatly improves the moving space of the lens and realizes the highest five-fold optical zoom in the mobile phone industry.

Optical zoom on a mobile phone is useful because compared with ordinary digital zoom, it is a lossless mechanical stretching pixel, that is, there is no loss of image quality after optical zoom. If the mobile phone may have a zoom of 10 times in the future and can shoot more scenes without losing the actual imaging, it is not a gimmick, just like a SLR with a cannon.

Mobile phone is a fixed focal length lens (except Samsung S4 zoom and Panasonic CM 1 mobile phone have real optical zoom), which is not a zoom lens in essence and has no optical zoom theory. For example, the focal length of the wide-angle main camera of the mobile phone is 26mm, and the focal length of the telephoto sub-camera is 78 mm ... 78 divided by 26 equals 3. The manufacturer claims that it is three times that of optical zoom. This is not true. Because the focal length between 26 and 78, for example, the most classic focal length equivalent to 35 mm seen by human eyes, for example, the focal length of 50 mm seen by human eyes, all focal lengths between 26 and 78 are realized by digital zoom cutting and amplification. If you continue to stretch and trim the zoom, the focal length will become 78 mm. If the zoom changes, the phone will disable the 26mm main camera and turn on the 78mm long focal length sub camera. So the advertisement says it's triple optical zoom. If you want to keep changing, keep stretching, magnifying and cutting, 20 times, 30 times, 40 times or even 60 times.