In article <4tiica$8k7@newsstand.cit.cornell.edu>, d_ruether@hotmail.com says...
>In article <4th6na$u0@usenet.ucs.indiana.edu>, jwitte@hamlet.ucs.indiana.edu
>says...
>
>> May be a stupid question, but is human vision closest to 50mm or
>>24mm? My photojurnalism teacher said that it was closest to 50mm, and
>>that was why 50mm was considered a "standard" lens. However, *I* can see
>>more than I can through my 50mm Nikkor, and a photo friend said human
>>vision was closer to 24mm. Could it be that the eye is 50mm when focused
>>on *only one* spot, but 24mm when it scans a scene (as it normally does
>>when seeing)?
>
>
>(NOT a stupid question!) Hmmm, where to begin....?
>
>Our vision (taking the combined coverage of both eyes), is most similar
>in both perspective and coverage to an 8mm full-circle fisheye lens on
>a 35mm camera that has been cropped both top (by the eye-brow area of
>the face) and bottom (by the cheek area of the face). We see a bit over
>180 degrees horizontally, but "only" roughly 110 degrees vertically
>(depending on facial structure). Most people attend most of the time
>to a very small central portion of their vision area (maybe the equivalent
>of a 1000-5000mm lens on 35mm?), with the area outside that very small
>angle serving as context for the small central vision spot. Unusual motion,
>other oddity, or something else of interest in the peripheral area draws
>our attention, and our central small "visual attention spot", to the
>subject.
>
>Since our "8mm fisheye vision" is cropped (the area where many of the
>characteristics of fisheye [spherical] perspective [that are thought
>of as distortions] occur is missing), and is peripheral (not attended to
>closely), it is easy for most people to assume that they see in rectangular
>perspective. Over a narrow central angle, all perspective types are
>nearly identical, but a wide-angle lens showing a much narrower angle of
>view than our eyes (say, 100 degrees), shows very unfamiliar characteristics
>near the edge of coverage compared with our 180 degree vision. (Also, it
>is physically impossible for a rectangular-perspective lens to approach
>180 degree coverage.) Cropped-fisheye perspective does account for the
>familiar characteristics of our vision that are different from those in
>even normal and moderately wide angle photo lenses: subject vertical lines
>stay roughly vertical and parallel when we look moderately up and down at
>a subject, unlike with rectangular-perspective lenses; forground-to-
>background size relationships look more natural in fisheye images
>than in similar-angle rectangular-perspective images; rounded objects
>only 40 degrees or so away from the center in rectangular perspective
>begin to look "squashed", but in spherical perspective (and with our
>vision), rounded objects remain virtually unchanged over a much wider
>angle).
>
>BTW, there are ways to become aware of (to "see") the curving of straight
>lines away from the center of our vision - and to know that we do see in
>spherical perspective, and not rectangular. (For another post, maybe...;-)
>Hope This Helps

Thinking about this a little more, it occured to me that, due to the
structure of the eye (roughly a sphere, with the single-element lens
near [but below] the surface, and with the image projected onto the
roughly hemispherical "film plane" with its forward edge not in the
same plane as the lens [I trust this description is not in error!]),
the perspective would not be completely of the spherical (fisheye)
type, though it would be much closer to it in characteristics than
to the rectangular type. BTW, the actual FL of the eye (or any other
optical system) tells you nothing about the angle of view, without
knowing both the size and the shape of the surface on which the lens
projects the image. Also, the 50mm "normal" lens was derived from the conventional format-normal dimension of the diagonal of the film image (43-44mm), later upped to about 50mm (perhaps for convenience of construction?).
Hope This Helps