what is the focal length of normal human eye
Answers
Answer:
This article started after I followed an online discussion about whether a 35mm or a 50mm lens on a full frame camera gives the equivalent field of view to normal human vision. This particular discussion immediately delved into the optical physics of the eye as a camera and lens — an understandable comparison since the eye consists of a front element (the cornea), an aperture ring (the iris and pupil), a lens, and a sensor (the retina).
Despite all the impressive mathematics thrown back and forth regarding the optical physics of the eyeball, the discussion didn’t quite seem to make sense logically, so I did a lot of reading of my own on the topic.
There won’t be any direct benefit from this article that will let you run out and take better photographs, but you might find it interesting. You may also find it incredibly boring, so I’ll give you my conclusion first, in the form of two quotes from Garry Winogrand:
A photograph is the illusion of a literal description of how the camera ‘saw’ a piece of time and space.
Photography is not about the thing photographed. It is about how that thing looks photographed.
Basically in doing all this research about how the human eye is like a camera, what I really learned is how human vision is not like a photograph. In a way, it explained to me why I so often find a photograph much more beautiful and interesting than I found the actual scene itself.
Answer:
the focal length of normal human eyes is 18.5 mm