Eye as a Camera

The function of our eyes is to enable us to see clearly the objects in our surroundings at variable distances and under various conditions of lights. This function is achieved by a very complex arrangement of structures in the eye. Our eye can be thought of as a very advanced camera. There are many similarities between our eye and a camera. Like in a camera the aim is to provide a well-focused image of the object onto the film at the back of the camera. Similarly in the eye, the retina, which is situated towards the back of the eye, works as the photographic film. The image is formed there and then the signal is sent from there to our brain through the optic nerve, and thus we perceive the objects around us. In fact, the retina is much more advanced than a photographic film because it can automatically change its sensitivity depending upon the amount of illumination present.

The rays of light enters the eye and passes through cornea and lens, which converge them so that it gets focused at the retina and a sharp image is formed. This function is akin to that of the lens of a camera. Once again the eye is superior, because the lens of the eye has the property to automatically adjust its power depending upon the location of the object of interest. Therefore, whenever we see from distance to near object, the lens of eye increases its curvature and thus is able to focus the image clearly onto the retina. The aperture (pupil) in the colored part (iris) of the eye is also adjustable according to the illumination of the surroundings. This is akin to the aperture of the diaphragm in a camera.

In a normal eye, the rays of light coming from a distant object gets focused by the cornea and the lens of the eye onto the retina and form a sharp image. When looking at a near object, the lens of the eye becomes more convex (accommodation) and thus its converging power is increased. This helps in focusing the near object clearly on the retina.