What happens inside the lens when we focus?

Question

Cameras

Good night, tell me what happens inside the lens when we focus and why in the end it is proportional to the distance to the focus point?

Answer 1

Nothing happens inside the lens: the simplest lens is one converging lens, a piece of glass.
Refresh your knowledge of school physics .
ps There are lenses with "internal focusing" - it is carried out by moving the lens block inside the lens, but this is a detail that is not essential for the answer.