Archived posting to the Leica Users Group, 2001/05/10

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Subject: [Leica] Leica lens coatings
From: John Hudson <xyyc@home.com>
Date: Thu, 10 May 2001 08:27:22 -0700

This article

http://www.f32.com/articles/article.asp?artID=102

contains the following quotation:

"Filters however, regardless of how well they are made, unfortunately do
influence the photographic image adversely. Lens performance is slightly
diminished, and due to the introduction of two more glass to air
surfaces, the possibility of internal reflections and flare is much
greater. Therefore some lens manufacturers design their lenses such that
they will not transmit any UV light. All the lenses for the Leica
cameras for instance use a special UV absorbing material, Absorban, to
cement the various lens elements together. In lenses without cemented
elements, this is assured via different means. The result is better lens
performance without the necessity of a UV filter."

My question is: for how long has Leica been using Absorban to cement the
various lens elements together? Would M lenses dating to the 1960's have
used this UV absorbing material? What about my first M lens acquired in
1965 [Summarit 50mm / f1.5]?

Is the author of the article fair in suggesting that Leica lenses
perform better without than with UV filters?

John Hudson
Vancouver, BC