Archived posting to the Leica Users Group, 2000/08/22

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Subject: [Leica] A rant on Pop Photo tests
From: Bryant <tbryant@wizard.net>
Date: Tue, 22 Aug 2000 21:48:00 +0000 ()

Hi Luggers,

   I've noted that Pop Photo's tests often show that the "better" Japanese
lenses often beat the Leica lenses,  e.g. the Canon 35mm f/1.4 vs the Asperic
35mm Summilux f/1.4.  We Luggers, and other more objective judges, do not
agree.

   I'd like to take a stab at explaining why this is so.

   Pop Phot tests lenses based on their flat field capability.  If you take
pictures of distant landscapes or brick walls with the lens wide open, this
makes sense.  Most of us don't, and Leica knows it.  Leica lenses have
considerable field curvature, unless Leica doesn't want it there, e.g. the
100mm F/2.8 Elmarit R Macro (Pop Phot raved about it.)  Allowing in a little
field curvature means that they can correct for other things that we notice
more, like spherical abberation, coma, or lateral chromatic abberation, or a
host of other optical nasties that translate to soft images.

   It's hard to believe that the Canon 35mm f/1.4 is better wide open than the
35mm Summilux f/1.4.  The Summilux can hang it's rear element as close to the
focal plane as it likes, the Canon can't.  This restriction cannot make for a
sharper lens.  Assuming both lenses were designed to deliver maximum
performance, cost no object, the Leica lens, with fewer design restrictions,
has got to be better.

   In practice, you might never see it, as hand holding is is one heck of an
irregular soft focus inducer!

   Now, Canon *knows* that they have to shine in the Pop Photo tests to sell
expensive lenses, so they design for flat fields.

   I'll go with Leica.

   Tom

Replies: Reply from Dante A Stella <dante@umich.edu> (Re: [Leica] A rant on Pop Photo tests)