Optical zoom focusing principle of camera

Zoom, you can't think of the lens as a simple convex lens. But the distance between many lenses changes, which eventually leads to the change of the equivalent focal length of the whole lens group. If you have to imagine a lens as a concave lens, you can imagine a lens with varying thickness. Because of the change of thickness, the focal length will change. That's zoom. -Sure, this.

Let's start with focusing. Anyone who has common sense in shooting knows that we zoom in first (zoom in and out) and then focus. In other words, only when the focal length is determined can we focus. At this time, because the focal length of the lens has been determined, it can be regarded as a convex lens. The focusing process is to change the distance between the convex lens and the negative (the digital camera is CCD, CMOS) (of course, it also changes the distance from the scene).

Simply put, the lens spacing changes, leading to zoom; The whole lens moves together, which is called focusing.

Of course, there are other methods in modern optics that can achieve focusing without moving all the lenses and ensure high precision and high speed. However, the result can be completely equivalent to the whole movement of the lens together. So, in the final analysis, the principle is still the same.

Your picture is obviously in front of focus. When the machine detects it, it will automatically adjust the distance of the lens, and the focus will fall on the plane of the negative or CCD.