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From: Alexandre Eremenko (no email)
Date: Sun Feb 13 2005 - 02:39:21 EST
On Sat, 12 Feb 2005, Frank Reed wrote:
> Interesting. I don't know anything about this.
> What can a typical trained
> marksman achieve in terms of angular accuracy?
0.4'-.5' without telescopic sights (See also Jared's message).
unlike Jared, I see some analogy between star shooting
and target shooting. In both cases, not only sharpness
of your eye but also firmness of your hand is relevant.
As I understand, a marksman does not really see the central circle
on the target s/he intends to hit. She only sees the larger circle,
but with some training she is able to aim at its center
with better accuracy than her eye resolution.
Something similar probably happens when an experienced observer
determines the touch of two discs as you described.
> know if there are any people who have
> genetically superior foveas in their
> eyes with the cones more tighly packed
According to my mother (an ophtalmologist), the density
of those cone packing does not vary much among people,
and 1' is the theoretical limit derived from this density.
However there are well documented cases of much higher resolution.
(One person tested in XIX century had resolution of 1",
but this seems to be the world record. Several people were described
who could see the phases of Venus with naked eye). The
reasons why some people
have such resolution is not known. Or at least was not known
30 years ago when my mother told me this.
By the way the well-known double star (Mizar, zeta of Big Diper)
was used to test the vision of ancient Arab warriors.
The distance is 12', so this was not a very rigorous test:-)
Alex.
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