What does physics have to do with camera lenses?
That has to do with camera lenses is optics, as the first poster mentioned. However, depending on the camera, you may have a couple of other branches involved — The camera may use an autofocus device. This may be infrared, optical, or ultrasonic. — Again, depending on the camera type, you may have motors that focus your lens. That has to do with mechanical couplings.
