Zoom of mobile phone camera

There are two kinds of zoom, one is digital zoom; One is optical zoom. The function is the same as that of a mobile phone, and most of them use digital zoom. Digital Zoom, also known as digital zoom, is called digital zoom in English. Digital zoom is to enlarge the area of each pixel in the picture through the processor in the digital camera, so as to achieve the purpose of enlargement. This method is like using image processing software to enlarge the area of a picture, but the program is carried out in a digital camera. Some pixels on the original CCD image sensor are enlarged by interpolation processing, and the pixels on the CCD image sensor are enlarged to the whole picture by interpolation algorithm.

Different from optical zoom, digital zoom is the change of the vertical direction of the photosensitive device, which gives people a zoom effect. The smaller the area on the photosensitive device, the user can only see part of the scene visually. However, because the focal length has not changed, the picture quality is worse than normal.

Through digital zoom, the shot scene is enlarged, but its definition will be reduced to some extent, so the practical significance of digital zoom is not great. The English name of Optical Zoom is Optical Zoom, and digital cameras rely on optical lens structure to achieve zoom. The optical zoom mode of a digital camera is similar to that of a traditional 35mm camera, that is, the scene to be shot is enlarged and reduced by moving the lens. The larger the optical zoom coefficient, the farther the scene is photographed.

Optical zoom is achieved by changing the positions of lens, object and focus. When the image plane moves in the horizontal direction, the visual field and focal length will change, and the farther scenery will become clearer, making people feel that the object is moving forward.

Obviously, there are two ways to change the perspective. One is to change the focal length of the lens. In photography, this is optical zoom. The focal length of the zoom lens is changed by changing the relative position of the lens. The other is to change the size of the imaging plane, that is, the diagonal length of the imaging plane. In digital photography at this time, this is called digital zoom. In fact, digital zoom does not change the focal length of the lens, but changes the viewing angle by changing the diagonal of the imaging plane, thus producing an effect equivalent to the focal length change of the lens.

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.