[Leica] Information on the Summarit, from those who repair or have had one repaired?

[sethrosner at nycap.rr.com (Seth Rosner)]

Hello again Vick and Gene:

I have just spoken with Ernst Hartmann, the service manager at Leica USA in 
Northvale NJ about our colloquy. Gene, you are right: Ernst's comment is 
that it is possible to reassemble the Summarit - and other Leitz/Leica 
lenses - correctly, assuming the right tools and assuming meticulous care in 
aligning each element perfectly, without collimating it.

That said, even with the highly trained technicians they have at Leica, they 
always check on a collimator each lens they have serviced. It is the only 
way they can be certain that there is no decentering and that the lens is to 
factory tolerances and will meet its performance standard.

Seth
----- Original Message ----- 
From: "Gene E. McCluney" <mccluney@sbcglobal.net>
To: "Leica Users Group" <lug@leica-users.org>
Sent: Monday, June 27, 2005 4:40 PM
Subject: Re: [Leica] Information on the Summarit,from those who repair or 
have had one repaired?


> >Exception noted, Gene    ;-)
>>
>>Perhaps Vic does not have a collimator, as I assume you do, to ensure that 
>>the lens elements are all perfectly centered on reassembly. Decentering is 
>>perhaps the most common cause of imagery problems with any lens system. 
>>Leitz/Leica's quality control has made this a virtual non-problem with 
>>their lenses.
>>
>>The front and rear elements of the Summarit are uncemented singlets. 
>>Assuming Vic is courageous enough to undertake the task.
>>
>>Thanks for your interesting take on lens servicing, Gene.
>>
>>Seth
>
>
> In all the Leica lenses that I have disassembled, the elements fit into 
> machined depressions in the
> lens mount.  Each element fits precisely.  I see no way an element can be 
> de-centered, as they
> fit exactly and precisely with no play.  In other words, it appears that 
> the "centering" is done
> during the fabrication and initial assembly, and subsequent dismantling 
> and re-assembly shouldn't
> affect the overall "centering" that is built into the lens. Disassembly ad 
> reassembly using the same lens elements should result in exactly the same 
> "factory" centering.
>
> The case for a lens needing "re-centering" using a collomator is highly 
> exaggerated, in my opinion ,
> at least when it comes to Leica lenses.  Just make notes of what goes 
> where when taking apart.  Some Leica lenses have thin fibre washers to 
> separate elements.  These should be put back exactly as originally 
> installed.  But even with this, the glass elements fit into milled 
> depressions in the lens mount structure, and cannot decenter laterally. 
> If the glass is "seated" when assembling then no de-centering will occur.
>
> The above is in reference to the "optical block" of a leica lens and does 
> not address the helical focusing mount, which is of course possible to 
> re-assemble incorrectly.   It is possible to disassemble the optical 
> elements of most lenses without disturbing the helical focusing mount 
> alignment.  There are a number of Leica lenses where the "optical block" 
> completely unscrews from the helical focusing mount, leaving the focusing 
> mount undisturbed.
>
> Gene McCluney
>
>
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