Archived posting to the Leica Users Group, 1998/03/23

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Subject: [Leica] No-filter convert
From: "Boreham" <boreham@dial.pipex.com>
Date: Mon, 23 Mar 1998 18:31:01 -0000

As a recent convert to the "no protective filter" school I offer the
following to encourage other people who feel naked without one!
It is an extract from the Broadsheet published by Williams of Hove (now
Hove Camera Co again) one of the biggest Leica agents in the UK. It is part
of an account of their tour of the factory at Solms.
" We were then shown an almost unbelievable test to check the hardness of
the coating on the front element of a lens. Definitely not something to try
at home this one"
"They take a wad of squidgy polymer compound into which is embedded an
extremely hard, gritty substance. This is brought directly into contact
with the coated surface of a lens element and ground into it at a
substantial pressure for a precisely measured time. OUCH ! At the end of
this process, the front element is examined with a powerful glass and if
there is any sign of scratching in the surface of the coating, the setting
of the coating machine is re-calibrated."
"Leica are so confident in their modern lens coatings that they maintain
the use of a UV filter on a current production lens is totally unnecessary.
This is not only because the coating is so hard that it does not need the
further physical protection of another piece of glass in front of it, but
also because the highly efficient modern coatings effectively filter out
the UV radiation without the need of any further assistance. Leica go even
further and say that there is a possibility that the use of a filter could
even degrade the performance of a lens."

Mike

P.S. For sale:- 3x Leica UV filters (E46), one B&W UV (E60) all unmarked !