How is a camera like an eye?
Any eye is like a camera in many ways, like if it is dark an eye's pupil will open up to let more light in and in a camera you have to open the lens to let more light so you get a clear photo. The lens is the eye of the camera. Its function is to bring light from the subject into focus on the film. A camera can have a single lens or a complex set of lenses. Together with the shutter, the lens controls the amount of light that enters the camera.
Which part of the eye controls the amount of light entering?
It is the Iris. This is the part of the eye which is responsible for one's eye color. It acts like the diaphragm of a camera, dilating and constricting the pupil to allow more or less light into the eye.
Together with the shutter, the lens controls the amount of light that enters the camera.
What Part of the eye is responsible for the vision and color?
It is the Retina. It has a thin tissue lining the innermost wall of the eye. The retina acts much like the film in a camera. The retina responds to light rays hitting it and converts them to electrical signals carried by the optic nerve to the brain. The outlying parts of the retina are responsible for peripheral vision while the center area, called the macula, is used for fine central vision and color vision. The very center of the macula is called the fovea. It has a very high concentration of special cells called cones which make it the only part of the retina capable of 20/20 vision.
What part of the eye does the focusing?
It is the crystalline lens. The lens is responsible for focusing light onto the retina. It changes shape slightly to allow us to change focus between objects that are near and those that are far. If you are looking into the distance your eye will try to focus at what you are trying to look at because if you look and something really close you lens will close up more and if you're looking into the distance your lens will open more to focus better. This process is called accommodation. As we age, the lens becomes less flexible and able to "accommodate" or change focus. Your eye can focus on up to 100,000 different distinct points in the visual field. In general the eyes of all animals are similar to simple cameras in that the lens of the eye forms a reversed image of objects in front of it on the sensitive retina, which corresponds to the film in a camera. A young child can see clearly at a distance as close as 6.3 cm (2.5 in), but with increasing age the lens gradually hardens, so that the limits of close seeing are approximately 15 cm at the age of 30 and 40 cm at the age of 50. This condition is known as presbyopia.