the iris and the lens focus the image to fall on the RETINA.
It makes an image to fall on the retina. For this function the thickness of the lens is changed according to the distance of the object.
The main force acting on an object in free fall is gravity. Gravity is the force of attraction between two objects with mass, causing them to accelerate towards each other. In free fall, the only force acting on the object is gravity, causing it to accelerate downwards at a constant rate of 9.8 m/s^2 near the surface of the Earth.
There's no fundamental reason that it should.
Mass does not cause an object to fall faster.
A falling object.
The object is said to be in free fall.
Human eye is optical miracle.Depending on the distance of the object, we have to change the position of the screen.In case of human eye, screen (Retina) is kept at fixed distance and eye lens is elastic and it becomes more or less thin or thick, so as to adjust image on retina. This phenomena is called accommodation. In near sighted persons lens is more convex than it should be. So we put concave lens in front of eye, so that image of distant object should fall on retina. Human brain is also miracle and after few days, it starts guessing the actual distance of the object.
free fall
Gravity causes an object to fall to Earth.
An object in free fall will fall approximately 64 feet in 2 seconds.
An object in free fall is one that has only the force of gravity acting upon it.
Gravity causes an object to fall from a height. Without gravity, the object would just be floating in the air.