Archived posting to the Leica Users Group, 1997/12/06

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Subject: [Leica] Leica's diffraction limited lenses
From: "Thomas J. Donovan" <75674.3465@compuserve.com>
Date: Sat, 6 Dec 1997 13:39:37 -0500
 
Eric Welch,

        >>As far as I know, Leica has only two diffraction limited lenses<<

  >>Seems to me diffraction limited is when the lens has optimum aperture<<
                                                      >>wide open<<

Per "Leica Fotografie", 8/93. page 27; " The optical performance of the
lens (280 f4) at full aperture is so remarkable that f4 can actually be
used as the "optimum" working aperture. Indeed, stopping down does not
really enhance the performance to any appreciable degree".  Indeed, per a
LHSA meeting in Kentucky, as I recall, the folks (Lothar Kolsch?) from
Leica Germany announced that the 280 f4 was a "diffraction" limited lens.

Eric, sure seems like your definition is similar to that of Leica Germany!
Given that the 280 f4 is one ( I own this one ) of the two; my guess on the
2nd lens ( based on
looking for a similar pattern in the BAS charts ) might be:  a.) the R-180
f2  b.) the R-70-180 APO (I own this one ).  c.) M-135 f4.  d.) the R-400
f2.8.  My guess would be that the second one is the R-180 f2 lens!

Tom D.