[Leica] 50mm rigid Summicron

[frank.dernie at btinternet.com (FRANK DERNIE)]

I have read that the rigid was designed to reduce  the vignetting inherent 
in the smaller elements needed in a lens capable of collapsing through the 
lens mount throat. I have element layout drawings at home - the difference 
between the collapsible and rigid is obvious. The same author wrote that the 
difference between the close focus and standard lens is only the mount, 
optically they are identical.
Frank

----- Original Message ----
From: Marc James Small <marcsmall@comcast.net>
To: Leica Users Group <lug@leica-users.org>; LUG <lug@leica-users.org>
Sent: Monday, 27 November, 2006 11:58:55 PM
Subject: Re: [Leica] 50mm rigid Summicron

At 06:11 PM 11/27/2006, Phil Swango wrote:
 >Marc Small wrote:
 >> I believe that the Rigid 2/5cm Summicron is identical
 >>optically to the DR/NF version of that lens, the only difference being in
 >>the lens mount, but I have never researched this and that could be a third
 >>design based on a common pattern.
 >
 >That's what Erwin Puts says too.  I don't know if he's a reliable source or
 >not.  I've had both and couldn't see any difference.

Phil

Measure them.  That is the difference.  The Rigid 
has a longer front element to rear element 
distance, which requires a redesign.  I did a LOT 
of research about this 12 years or so ago, back 
in my days on Hummingbird Lane, but my notes are 
not with me at the moment, and my leaky memory 
nly recalls that there is definitely a redesign 
of the collapsible to rigid design and, probably, 
a further redesign to the NF version.  Leitz was 
being slammed hard at the time over its lens 
designs which made them most unwilling to discuss 
these redesigns or those of the 1.4/50 Summilux, 
not admitted until 1966, some four years after that revised lens appeared.

Mandler seems to have been the brains behind the 
redesign of the collapsible Summicron to the 
rigid lens.  Wright and Glanfield were the first 
to note the discrepancy but the man who made it 
obvious was the late and VERY lamented Bob Schwalberg.

I am embarrassed to be caught, once again, 
without my notes at hand, but I will confidently 
state that the rigid Summicron has a greater 
depth than does the collapsible lens, and that 
the collapsbile Summicron design was clearly 
tweaked by Mandler to produce the rigid Summicron 
design which was, most likely, further tweaked 
for the NF version of the rigid M BM lens.

I do recognize that Leitz has maintained that 
these lenses were identical in design.  However, 
operating from memory, there are differences in 
the patents for these lenses and, I vaguely 
recall, an internal Leitz memo discussing this surfaced some years back.

I had promised the late Roy Moss an article on 
this during his tenure as VIEWFINDER editor but 
it got set aside in the course of my work on my 
Zeiss book and I just never got back to it, 
though I did get a prompting e-mail on this from Roy from around 1995.

Marc


msmall@aya.yale.edu
Cha robh b?s fir gun ghr?s fir!



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