How do digital cameras adjust their focus?

Camera's consists of a lens (to form an image) and a sensor(to capture the image formed by lens). To capture a properly focussed image, the sensor must always be present at the focal plane (The plane where image is formed, see image below). read more

So, on a camera with a lens that has a rotating mechanical focus ring, by turning this ring you will physically move the focusing lens, or lens-focusing group, to manually change the distance between the lens and sensor and allow the control of where in the camera that light converges. read more

In addition to controlling the amount of light, the camera has to adjust the lenses to control how the light is focused on the sensor. In general, the lenses on digital cameras are very similar to conventional camera lenses -- some digital cameras can even use conventional lenses. read more