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

[mccluney at sbcglobal.net (Gene E. McCluney)]

>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