Archived posting to the Leica Users Group, 2012/04/07

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Subject: [Leica] When a Biogon is no match for THE Biogon
From: benedenia at gmail.com (Marty Deveney)
Date: Sun, 8 Apr 2012 10:15:39 +0930
References: <CAF8hL-FHOzYfurv9pp1a3+u1f3_39HGYsohp-=vvN=HOdG+Z9w@mail.gmail.com> <CABmfTOXQYh21UQ5kbtt+h_-9F=XFsOV-p7--mfH2c4UMaoHC1g@mail.gmail.com> <20120406141008.GW69877@selenium.125px.com> <CABmfTOW2F2p1H+ASbFgN7+ButbovFGEiqXrtRBq2vWbsQ6=C_w@mail.gmail.com> <20120407145311.GA819@selenium.125px.com>

On Sun, Apr 8, 2012 at 12:23 AM, Tim Gray <tgray at 125px.com> wrote:
> The ZM 21/4.5 DOES have the same size exit and entrance pupils. ?For that
> matter, so does the 28 Summicron. ?Not that they are 100% by the book
> symmetric lenses, but...

That makes sense.  The wavy distortion will be there if the front
group is negative, irrespective of the entrance and exit pupils, and
the distortion charts show this.  I can't find figures for the exit
pupils of these lenses, but it makes sense to use a symmetrical design
with a negative front element to move the rear element away from the
shutter.

Marty


Replies: Reply from tgray at 125px.com (Tim Gray) ([Leica] When a Biogon is no match for THE Biogon)
In reply to: Message from richard at richardmanphoto.com (Richard Man) ([Leica] When a Biogon is no match for THE Biogon)
Message from benedenia at gmail.com (Marty Deveney) ([Leica] When a Biogon is no match for THE Biogon)
Message from tgray at 125px.com (Tim Gray) ([Leica] When a Biogon is no match for THE Biogon)
Message from benedenia at gmail.com (Marty Deveney) ([Leica] When a Biogon is no match for THE Biogon)
Message from tgray at 125px.com (Tim Gray) ([Leica] When a Biogon is no match for THE Biogon)