[rollei_list] [slight OT] A Sonnar 1.5/50 + coatings at Kodak as of 1940
- From: Emmanuel Bigler <Emmanuel.Bigler@xxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Fri, 16 Jan 2009 10:05:44 +0100
From Richard Knoppow :
.....
Kodak began coating quite early. A few premium Kodak lenses had soft
coatings on internal surfaces by about 1940. These included the Eastman
Ektar series...............a noticable ghost image of very bright objects in the image field, an
effect which does not occur in the later, coated version.
The Sonnar was designed with flare in mind..... The use of designs
with a muntiplicity of cemented surfaces to avoid glass/air surfaces
stopped almost immediately when coatings became available.
Thanks you very much Richard !
You mention that Kodak coated lenses as of 1940 ; this raises two questions:
- could you elaboarte on the notions of soft and hard coatings ?
- to the best of my knowledge, Zeiss (Smakula, 1935 ?) had a patent on
the anti-reflection coating, how could Kodak get around this patent ?
Or was-it simply that Zeiss did not have a US patent ? Or during the
war, the question of enforcing patents was irrelevant ?(even if the US
were not at war in 1940)
Regarding patents and WW-II : I read in Pierre Glafkidès huge book on
photographic physics and chemistry that German patents were cancelled
afert the war. This, for example, allowed MPP in the UK to copy freely
some features patented by Linhof for the Technika. Probably, some Carl
Zeiss and Rolleiflex patents were also cancelled !
--
Emmanuel
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