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Frank,

I read recently on another list that the density of photoreceptors in
the eye is not a limiting factor in its resolution, apparently because
the eye can move.  Unfortunately, I don't have time right not to dig
this out and put it up for review.

Fred

On Feb 16, 2005, at 2:05 PM, Frank Reed wrote:

>
>
>  Alex, you wrote earlier:
> "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)."
>
> I mentioned before that I was skeptical, and it only dawned on me
> while I was throwing out last week's back-of-the-envelope calculations
> that one arc-second resolution is literally impossible. The
> diffraction limit is imposed by the laws of physics and gives a lower
> limit of 15 arcseconds under the very best of circumstances (under
> typical circumstances, this optical limit is about 30"). If Nature
> chose to pack more cone cells into our foveas than one for every 15"
> of angle across the retina, they would not yield higher resolution.
>
> Can anyone think of a loophole I've missed here? The diffraction limit
> has some fuzziness of definition (there's a pun in there somewhere),
> but I don't think it's enough to help.
>
> -FER
> 42.0N 87.7W, or 41.4N 72.1W.
> www.HistoricalAtlas.com/lunars
>

   

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