Difference between revisions of Eyeballs
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== [[wikipedia:back of the envelope|Back-of-the-envelope]] calculations == | == [[wikipedia:back of the envelope|Back-of-the-envelope]] calculations == | ||
We can use [[Optics related math]] and some very approximate numbers to give order-of-magnitude estimates of some of the | We can use [[Optics related math]] and some very approximate numbers to give order-of-magnitude estimates of some of the quantities involved. | ||
To estimate the focusing power of an [[emmetropic eye]], we might take the [[axial length]] as around 2.5cm. For [[distance vision]] (parallel incident light) that number is simply the [[focal length]] of the eye at rest, giving 40 [[Diopters]]. If we take the [[near point]] as about 25cm, that requires an additional 4 dpt of focusing power from the lens. | To estimate the focusing power of an [[emmetropic eye]], we might take the [[axial length]] as around 2.5cm. For [[distance vision]] (parallel incident light) that number is simply the [[focal length]] of the eye at rest, giving 40 [[Diopters]]. If we take the [[near point]] as about 25cm, that requires an additional 4 dpt of focusing power from the lens. | ||