[Leica] Don's PAW 25 de plane, de plane

[henningw at archiphoto.com (Henning Wulff)]

At 9:51 PM -0400 6/16/04, Don Dory wrote:
>Robert,
>You asked for an example so this one will work:
>
>http://gallery.leica-users.org/On-the-road/tooueylaugh_copy
>
>I was trying to document the last few months of this woman's life by
>getting in close to her and her friends.  The women on the right may be
>less than 2 feet from the lens yet her head registers as a normal human
>head.  The retrofocus lenses that I have for SLR's would make them much
>more elongated.
>
>I hope this helps.
>
>Don
>dorysrus@mindspring.com
>
>-----Original Message-----
>From: lug-bounces+dorysrus=mindspring.com@leica-users.org
>[mailto:lug-bounces+dorysrus=mindspring.com@leica-users.org] On Behalf
>Of robertmeier@usjet.net
>Sent: Tuesday, June 15, 2004 10:59 PM
>To: Leica Users Group
>Subject: Re: [Leica] Don's PAW 25 de plane, de plane
>
>Don,
>
>The 21 SA repeals the laws of optics?   Something circular in the corner
>of
>the frame does not become an oval with the 21 SA?   Please post a
>picture to
>show this miracle.
>
>Bob

Don, I think you aren't quite sure of what 'lens distortion' is 
either. The difference in linear distortion displayed by the SA on an 
M and a typical SLR lens will have essentially no discernible 
difference in the rendering of these women's heads. If the SLR lens 
displays the all-too-common barrel distortion, the perspective 
distortion that it would display away from center would actually be 
(imperceptibly) less than that of the SA.

SLR lenses typically display barrel distortion in the zone 5 to 12mm 
off axis, go towards neutral at 15 and then change to pincushion 
distortion beyond 18mm. This results in the characteristic 
'moustache' distortion of strongly retrofocus designs.

-- 
    *            Henning J. Wulff
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