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.
The light started from the object must have arrived exactly at one point on the retina to see things in detail. On the other hand, if the light from one point of the object is scattered all over the retina, we will perceive things faintly.
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.