Archived posting to the Leica Users Group, 1997/11/20

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Subject: Re: "Roundness" a mythical construct?
From: dannyg1@IDT.NET
Date: Thu, 20 Nov 1997 21:26:22 +0000

Dave,

Something tells me this post isn't going to be a good idea.....

Though I'm not sure, it could be an effect I notice often, Tessar lenses have a very flat 
rendition that seems a linear representation of the world, translated more perfectly to the 
film. A six element Planar style lens seems to me to be more prone to a 'stretchy' edge 
effect that makes its rendition appear more 'round' to me.

Whether all of this is a personal perception or a reality, I notice it in other peoples work 
as well, so I suppose that it's demonstrable on a testbench.There are some notable 
Planar-style exceptions (the 50 'cron is one), but most of the time I notice it. 

Examples of lenses that seem to have the most roundness (to me at least) are the 135/3.5 
Xenotar for 4x5 and the 80mm/2.8 Xenotar on my Rollei D.

OK guys, let the feathering begin. 

Danny Gonzalez