Archived posting to the Leica Users Group, 2001/05/28

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Subject: Re: [Leica] Re: Cleaning Marks/ Recoating
From: Marc James Small <msmall@roanoke.infi.net>
Date: Mon, 28 May 2001 09:40:25 -0400
References: <200105280123.SAA20873@mejac.palo-alto.ca.us>

At 11:48 PM 5/27/2001 -0400, Douglas Cooper wrote:
>Ken Ruth (another
>legendary repairman) told me that it's impossible to grind and recoat a lens
>without doing damage.

I hate to speak for Ken, but the above certainly does NOT reflect more than
ten years of conversations I have had with him on this topic.  I would
suspect that Ken probably gave you VERY cautious advice, along the lines of
'regrinding of a lens can change the optical performance'.

In any event, most "cleaning marks" on older Leica glass are not "cleaning
marks" at all, but artifacts of the wet coatings used by Leica until 1958;
these coatings dry out and leave identifiable marks on the lens.  Having
these removed and the lens recoated will not alter the optical properties,
as no glass is removed.  A true nick or ding or gouge is a different
matter:  if the lens is otherwise all right, then perhaps the best thing to
do is to blacken the gouge with a magic marker of some sort to reduce flare.

Marc

msmall@roanoke.infi.net  FAX:  +540/343-7315
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