Archived posting to the Leica Users Group, 1997/12/04

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Subject: Re: [Leica] RE: soft focus vs out -of- focus in an ultimate sharpness world
From: Jim Brick <jim@brick.org>
Date: Thu, 04 Dec 1997 22:52:43 -0800
 
At 10:00 PM 12/4/97 -0800, you wrote:
>At 11:00 PM 12/3/97 -0600, Eric Welch wrote:
>>As far as I know, Leica has only two diffraction-limited lenses. So what
>>good are those numbers?
>
>I think your question assumes that if a lens isn't diffraction-limited,
>then diffraction doesn't matter.  This is a "weakest link" view of how a
>photographic system works -- the weakest link in a chain fails first.  But
>that isn't how photographic systems work -- instead, the loss of sharpness
>is cumulative.
>
>...(the blood & guts of lens diffraction)
>
>A "diffraction-limited" optical system is one in which aberrations are so
>small that the primary factor affecting image quality is the aperture
>diffraction.
>
>-Patrick
>

Very cool dissertation Patrick.

Thanks,

Jim