Re: Seeing the field stop

Brad Isley <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...

> One of the visual tests given to prospective naval aviators is a
> peripheral vision test.

It is not clear to me that extreme peripheral vision has anything
to do with the question at hand.  Obviously, peripheral vision
(a.k.a. averted vision) is relevant for astronomy, but when people
use averted vision intentionally, they use a part fairly close to
the fovea -- off by perhaps 10-20 degrees, at a guess.

Extreme peripheral vision, the kind that extends to 180 degrees,
is useful mostly for detecting motion, or for detecting the
presence of very large and obvious objects.  You certainly
cannot count cinder blocks with extreme peripheral vision,
nor can you determine whether an EP is "sharp to the edge", as
the expression goes.

> BTW: I have no trouble seeing the field stop on a Nagler ep.

I assume that in this case, you are talking about direct (foveal)
vision?  This would seem to be a matter of the geometry of the
eye and head; you can see with the fovea when and only when
the eye is pointed directly at the target.

    - Tony Flanders