Focus adjustment of the camera
The eye focuses by adjusting the thickness of the lens.
On the other hand, the camera focuses by adjusting the position of the lens.
To view objects in detail, the light originating from one point on the object must be accurately gathered at one point on the retina. If the lights are scattered all over the retina, we will lost the focus.
In order to gather the emitted light into one point of the retina, there must be a device that acts as a convex lens. This is the cornea and lens of the eye.