[rollei_list] Lens Coating History, Take 79
- From: Marc James Small <marcsmall@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 04 Mar 2010 00:58:40 -0500
At 12:43 AM 3/4/2010, Richard Knoppow wrote:
> Working coatings were developed very early but they
>were not practical for production lenses. Smakula, of Zeiss,
>worked on vacuum deposition of metallic oxide coatings as
>early as 1935 but Zeiss does not appear to have applied them
>to production lenses. Perhaps because the early methods
>produced coatings which were too soft to withstand normal
>cleaning. Others experimented with chemical coatings. Here
>again, the results were successful in terms of reducing
>surface reflections but the coatings were not rugged enough
>to be practical.
> The technique of hard coating was developed in the US
>during WW-2 (sorry Marc, this is well documented).
Richard, your facts are wildly in error.
First, the Smakula process produces HARD
coatings, unlike the earlier drip technologies.
Second, Zeiss began coating production optics in
1937. I own a 1.5/5cm CZJ Sonnar T in Contax RF
BM sold at Roanoke Photo-Finishing in March,
1939, with a Contax III camera. Almost all CZJ
military production from 1936 until 1945 was
hard-coated, one reason the Allied military
always tried to acquire Zeiss binoculars and
rangefinders whenever possible. Schneider also
shared in the use of the process from 1939
onwards. Almost all Zeiss industrial and medical
gear was hard-coated after 1940, as were all of
the CZJ lenses in LTM sold to Sweden to pay for those ball-bearings.
Third, Kodak introduced hard coatings immediately
before the War broke out, as did Wray in the
UK. Most Wartime Barr & Stroud gear is
hard-coated using the Wray process. All three
processes were essentially identical: all of the
work up to Smakula's was, after all, in the
public domain, such as Bauer's identification of
Magnesium Fluoride as the proper coating
material. The use of vacuum to deposit the film
was "more one of technology than a jump of
genius", as Smakula told his grandson late in
life. For that matter, Zeiss published the
details of the Smakula process in the summer of
1940, so it was secret no longer.
Fourth, hard coating technology existed by 1940,
having been independently developed in Germany by
Zeiss, in the US by Kodak, and in the UK by
Wray. The requirements of military production
kept this from being a common item on
photographic lenses until after the War ended,
but Zeiss certainly was marketing coated lenses
in the public market by 1939, and Kodak by
1940. The Smakula process certainly used baking,
and I suspect the Kodak process did as well. I
know that the Wray method used this as well --
the workers hated the smell of the burners which
provided the heat. Why the US government
insisted on re-inventing the wheel during the War
escapes me, but, then, government is all too
often the least efficient method for getting things done!
Zeiss and Leitz both offered to coat uncoated
lenses up to around 1970, incidentally. Zeiss
USA had a special facility for this in New York City.
So, we are not in disagreement, save for your
contention that the Zeiss, Kodak, and Wray
processes produced a "soft" coating, and the date
of introduction. All three processes produced a
hard coating, and Zeiss and Kodak both marketed
hard-coated lenses prior to WWII.
The record on this is clear and certain.
Marc
msmall@xxxxxxxxxxxx
Cha robh bàs fir gun ghràs fir!
---
Rollei List
- Post to rollei_list@xxxxxxxxxxxxx
- Subscribe at rollei_list-request@xxxxxxxxxxxxx with 'subscribe'
in the subject field OR by logging into www.freelists.org
- Unsubscribe at rollei_list-request@xxxxxxxxxxxxx with
'unsubscribe' in the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
//www.freelists.org/archives/rollei_list
Other related posts:
