Archived posting to the Leica Users Group, 1997/12/12

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Subject: Re: Was: Re: [Leica] filters for M-lenses; Now: ABSORBAN
From: Jim Brick <jim@brick.org>
Date: Fri, 12 Dec 1997 18:37:28 -0800

At 03:45 PM 12/12/97 -0900, you wrote:
>
>>
>>If you want lens protection, use a lens cap. If your lenses are less than
>>30 years old, you don't need a UV-filter as UV inhibitor is in the lens
>>cement.
>>
>>My advice... don't buy a UV filter at all. Buy film.
>>
>>Jim
>
>Does anyone on the list know when Leitz commenced using ABSORBAN in their
lenses? Date and or serial number, any particular lenses?
>
>While we are at it:  When did they start using multicoating?
>

I have a publication called EPOCH and was produced by the National Camera
Exchange. This particular issue is dated Fall/Winter 1985. The article was
called "Lenses Are Just Made of Glass." It states that "Leitz developed a
special cement, replacing the Canada Balsam, that had the properties of a
UV filter." They state that this was developed sometime in the fifties. So
that could be 1959 or 1950. This is also the article that a Leica lens
designer was quoted... "If we had meant for our lenses to have a flat piece
of glass in front, we would have designed them that way." The article also
said that "any filter adds aberration, very much like spherical aberration.
This will be more pronounced with thicker filters, but even thinner better
filters, produce this effect."

Jim