Archived posting to the Leica Users Group, 2001/05/10

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Subject: Re: [Leica] Leica lens coatings
From: Marc James Small <msmall@roanoke.infi.net>
Date: Thu, 10 May 2001 15:33:27 -0400

At 10:53 AM 5/10/2001 -0700, Mark Bohrer wrote:
>John:
>All I know is that my 1954-vintage 50mm F1.5 Summarit ended up with a very 
>scratched front element after repeated cleanings with lens tissue over many 
>years of use (1969-1975). It was pristine when I found it in my parents 
>basement. If I'd bought and used an E41 UV filter, it would have stayed 
>pristine.

No, it would not have "stayed pristine", Mark.  Leitz was barred in 1954
from using the vacuum-coating technologies controlled by Zeiss (though
Voigtländer and Schneider did have access to the process).  Hence, Leitz
was forced to use the older 'drip-coating' method, which left a very moist
coat.  Over time, this dries out and leaves a powdery residue which can be
easily rubbed off.  If your lens had been given a proper T-coating, of
course, the coating would have been MUCH harder.  (I have some Prewar and
Wartime Zeiss lenses which still have "pristine" coatings despite never
having been routinely covered with a filter of any sort.)

Marc

msmall@roanoke.infi.net  FAX:  +540/343-7315
Cha robh bas fir gun ghras fir!

Replies: Reply from Marc James Small <msmall@roanoke.infi.net> (RE: [Leica] Leica lens coatings)