Re: Resolution / depth of field (was Stellar by sunlight)

[Brian Whatcott <inet@INTELLISYS.NET>]

At 10:30 AM 3/28/02, Gary Turner wrote:
> ...
> As the pin-hole gets smaller, depth of field increases. ...
> However, as the hole gets smaller, resolution gets worse. ...
> Here is the argument I have heard for the aperture effect though.
>
> theta_min = 1.22 (wavelength / diameter) for a circular aperture.  If you
> can make your pupils dilate to twice their original size, theta_min becomes
> half of what it was - you can read words that are twice as far away as
> before.


While theta_min may improve, you may well find that you read text
 less clearly by twilight than during a sunny afternoon .   The resolution
limit mentioned is a pragmatic estimator. Sadly, the best resolution limit
is often dominated by aberrations. On the other hand, this limit can also
be circumvented.

Happily, visual acuity is something that is amenable to experimental
verification, I'd think.





Brian Whatcott
  Altus OK                      Eureka!