2006-11-27 02:34:05 · 2 answers · asked by esanjay_raj 1 in Science & Mathematics ➔ Physics
The optometrist does it every day with his special equipment that looks into the human eye with a light source. The normal eye has a 20/20 vision. The equipment analyses the vision fomed formed on the retina. The sharpness of the image determines if the image is formed behind, on or in-front of the retina. This distortion of the eyeball is resulting in near-sightedness or far-sightedness.
The corrective lenses assist in reproducing the correct image at the retina taht is in perfect focus.
The shape of the human eye would determine its focal length. Perhaps the question should be what's the focal length of a human eye with 20/20 vision.
2006-11-27 06:07:40 · answer #1 · answered by Anonymous · 0⤊ 0⤋
Hi. From the lens to the retina, about 50mm. (That is why a camera's 50mm lens is considered 'normal'.)
2006-11-27 02:42:21 · answer #2 · answered by Cirric 7 · 0⤊ 0⤋