Why do wide-angle cameras change easily?

This is an aberration. The straight line on the object becomes a curve after being imaged by the lens. The distortion is caused by the change of the magnification of the lens with the angle between the beam and the principal axis. The farther the light is from the main axis, the greater the distortion, but if it is orthogonal to the main axis and passes through it, it will not be distorted. The magnification increases with the increase of incident angle, which is called pincushion distortion. (i.e., pincushion distortion figure 20b). Negative distortion when the magnification decreases with the increase of incident angle (that is, barrel distortion figure 20c). In other words, the farther the object point is from the optical axis, the greater the magnification, and the distortion will occur; If the object point is far away from the optical axis, the smaller the magnification, the negative distortion will occur. Especially when the lens diopter is large, the image distortion is serious. As a result of the distortion, the object seems to have lost its original correct shape. The way to reduce the distortion is to change the shape of a single lens and adopt the best shape to minimize the distortion.