How does a digital camera without moving parts focus on a subject?

Question

Iron

Many mobile phones are equipped with cheap cameras: matrix + lens .. I don’t understand how focusing happens? what kind of algorithm is this? or all the same there is a moving element, such as a piezoelectric motor? then the question is about the algorithm? recommend literature?

Answer 1

There is a moving element.
It is not only in the Lytro camera, in which the focus is directed after shooting to any place.
And then about Lytro, I seem to be mistaken. The moving element is in the new Lytro.
About focusing after shooting - https://ru.wikipedia.org/wiki/%D0%9F%D0%BB%D0%B5%D...

Answer 2

You just don't see that there's also a lens in the camera that moves with piezoelectric motors. In some phones it can even be heard.

Answer 3

Another option is Hyperfocal distance
https://en.wikipedia.org/wiki/%D0%93%D0%BB%D1%83%D...