Archived posting to the Leica Users Group, 1998/01/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]At 12:04 AM 1/31/98 EST, Tom Shea wrote: >Modern coatings are very hard, but older coatings were soft. One of >the first coatings was magnesium fluoride which was so soft that its was quite >impractical for the outside of front and rear elements. > Well, modern coatings are still based on MgF; the difference is in the coating method. Zeiss got the patent on the vacuum-deposit technology in '35 or so, and wouldn't share it with Leitz (though they did license it to JSK and Zeiss-owned Voigtlander). So Leitz lenses were coated with a drip method which left a moist, soft coating, until the Zeiss patent expired in the late 1950's. Note that most Zeiss T lenses and the products of Schneider and Voigtlander from the '40's and '50's do not display the soft coatings which afflict Leitz glass of the era. Marc msmall@roanoke.infi.net FAX: +540/343-7315 Cha robh bas fir gun ghras fir!