Archived posting to the Leica Users Group, 2001/11/01

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Subject: Re: [Leica] Photodo ratings for 35mm Summilux -MASPH and 50mm Summilux-M
From: Dante Stella <dante@umich.edu>
Date: Thu, 1 Nov 2001 13:08:43 -0500 (EST)

B.D.:

Something is wrong with the testing?  I say live by the sword, die by it.
People on this group are fascinated with MTF and even more fascinated with
resolution testing.  If that's the shorthand you want to use, you are
going to find testing regimes were Leica comes out behind (note that Leica
rarely publishes MTF figures).  If the testing procedure is done
consistently, and it makes some Leica lenses better, then you have to
accept that some will do worse.  Questioning the systemic considerations
that lead to a low score for one lens questions the high scores too.

When it comes down to it, no modern prime lens would ever do poorly
enough, resolution-wise for it to be the drag on an optical system that
ends in output: a "good print" is 6lp/mm on the negative (precisely why
minilab prints can never be indicative of quality); scanning, 20lp/mm;
printing b/w, 60lp/mm.  The real problem is substandard image-processing
equipment.  MTF is a combination of resolution and contrast, and it is
safe to assume that the floor for making "good" prints could be quite low.

The upshot of this is that the only compelling reason to buy one
particular lens over another, length and relative aperture being equal,
is a difference in aberration characteristics, or the "fingerprint."




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Replies: Reply from "B. D. Colen" <bdcolen@earthlink.net> (Re: [Leica] Photodo ratings for 35mm Summilux -MASPH and 50mmSummilux-M)