Archived posting to the Leica Users Group, 2003/08/26

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Subject: diffraction (was Re: [Leica] Leica 90mm f/4.0 Elmar C prices)
From: Doug Herr <telyt@earthlink.net>
Date: Tue, 26 Aug 2003 18:59:41 -0700

on 8/26/03 6:28 PM, Marc James Small at msmall@infionline.net wrote:

> Note how many of the Leitz and Contax lenses made
> before the War stop down only to f/8 or f/9 or so, as the manufacturers
> were concerned over diffraction degradation beyond that point.  (The Zeiss
> Jena 1.5/5cm Sonnar, for instance, went from f/8, f/11, f/16, and then f/22
> between 1937 and 1945, as the effects of coating were confirmed to combat
> diffraction effects.  My oldest of these lenses is a quite early coated
> one, but only stops to f/11.)
> 
> Marc
>

How would coatings change diffraction effects?  I thought internal
reflections and diffraction were completely independant.

Doug Herr
Birdman of Sacramento
http://www.wildlightphoto.com


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