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