Re: Coatings on Early M Lenses

["C.M. Fortunko" <fortunko@boulder.nist.gov>]

I will second this. Van Stelten is local and a hell of a nice and competent
guy. I don't think he does this in his shop in Louisville, since I did not
see any equipment there. However, the work gets done correctly. I know this
on "good authority."

I did not know about the drip process. However, a friend of mine who worked
at Leitz in the 1980s, did not think that Leitz coatings were state of the
art at that time.

I have a DR Summicron with a superb coating. Could it have been redone? My
DR looks very good and much different from the other Summicrons (Rigid, DR,
and collapsible) I have seen. Many of them seem to have a shiny quality,
which a sales person in Palo Alto attributed to incorrect cleaning.

A friend of mine (Robert Benjamin) in Boulder, and a Leica expert (now at
Jones Drug at Camera),  attributes the bad condition of some of the older
lenses to overuse of Kodak lens cleaner. He does not recommend the use of
this particular concoction at all. According to him, RoR should be used at
most once a year.

Best regards,

Chris


Chris


At 12:22 AM 8/3/96 -0400, you wrote:
>Leitz was not granted permission to use the Zeiss vacuum-coating technique
>developed by Alexander Smakula and patented by Zeiss in 1936 and 1940;
>thus, Leitz used a drip process which produced a much moister and softer
>front coating  -- many lenses of the period from the lesser manufacturers
>were coated on internal elements only for this very reason, though I cannot
>recall that Leitz ever did so.  The Zeiss patent expired, I believe, in
>1960, and Leitz was vacuum coating their lenses shortly thereafter.
>
>These coatings dry out with time and need replaced.  John Van Stelten in
>Louisville Colorado does this for about $100 a lens.  He's efficient and
>quick, and the results can be astonishingly good.
>
>This is a handy buyer's point:  many dealers don't understand the history of
>technology, and simply ascribe the dried coatings to 'wipe marks' and
>discount the lens substantially.  Shop around, and you can get some buys.
>
>Marc
>
>msmall@roanoke.infi.net  FAX:  +540/343-7315
>Cha robh bas fir gun ghras fir!
>
>
>