Archived posting to the Leica Users Group, 1998/09/26

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Subject: Re: [Leica] Content-Type: text/plain
Date: Sat, 26 Sep 1998 14:35:37 EDT

> At 10:16 AM 26-09-98 PDT, you wrote:
>  >Hi LUGers,
>  >
>  >I have a question I should probably direct to Leica USA but they're 
>  >closed for the weekend so I figured I'd try it out here.  I was twisting 
>  >off a stuck filter on my lens today... after I finally got it off, I 
>  >noticed that the engraved front part of the lens (bearing "E46 37488xx 
>  >LEICA SUMMILUX-M 1:1.4/35 ASPH.") had shifted approximately 30 degrees 
>  >in the direction of twist.  With the filter off, I tried to see if I 
>  >could twist it back, or even twist it more, but it won't budge now.
>  >
>  >I'm wondering if it's possible that I damaged the lens.  I don't think 
>  >it's likely but I thought I'd ask, just in case.  Anyone ever had this 
>  >happen?
>  >
>  >Thanks!
    If the assembly which is loosening contains lens elements or a group, even
the slightest twist on a helical thread would put the lens slightly out of
collimation.  You could probably re-tighten your Summilux yourself but if it
has started to unscrew it probably ought to be professionally re-tightened,
collimated, and any screws or compound* replaced which have been sheared

*I'd heard from some Leica repair techs that in recent years Leica has been
using thread locking compound (euphamism for GLUE) to assemble various lens
mount components.  Not a bad thing, except that concurrently they've reduced
the # of or eliminated the little setscrews around the periphery.  I dismissed
it with "no way, Leica would *never* glue their lenses together!"...that is
until I had the entire front assembly of a 3rd-generation (E49) 28 Elmarit-M
(a borrowed one at that!) unscrew and dump the diaphragm blades all over the
floor.  (I was trying to remove the lenshood and didn't know you had to push
it in before turning it!)  Leica gladly re-assembled my friend's 28 (hopefully
with stronger glue!) but it was a shocking experience.  Of course, Leica (or
the owner of the lens) could use red Loctite and it would *never* come
unscrewed, but then for a CLA teardown a repair tech would have to heat the
lens to 500F, so that's probably not the best idea ;)