How many times does the camera reduce the original image?

This is actually not fixed. The key doesn't depend on the lens. Rather, it depends on the distance from the subject to the lens when shooting. If you zoom in far away, the magnification will be bigger; if you are near, the magnification will be smaller. With the same lens, the same person can be shot in close-up, half-length or full-length, or even the person is a little smaller.

Based on the principle of imaging similar triangles. The magnification you want is roughly the distance from the subject to the lens compared to the focal length of the lens. If you think about it carefully, it's easy to understand.