Archived posting to the Leica Users Group, 1997/12/20

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Subject: Re: [Leica] Focusing long lenses (long)
From: Eric Welch <ewelch@ponyexpress.net>
Date: Sat, 20 Dec 1997 23:27:19 -0600

At 05:12 PM 12/20/97 -0800, you wrote:

>If Canon has a patent _now_, I would think that they had a patent then.
>You're flipping cause and effect.

They are the only company that does it for a reason. And it has nothing to
do with patents. It's too difficult for others to do. They don't have the
ability to grow the crystals big enough, and flourite crystals big enough
to grind into lens elements don't occur very often in nature. And they are
brittle, and they are more effected by temperature than optical glass.
Those are all the reasons. It's not worth the hassle to other companies.
Patents have nothing to do with it. 

These things I know for a fact. It's in Canon's literature. All you have to
do is a bit of reading from the old days (late 70s early 80s when I was a
faithful Canon user).

==========

Eric Welch
St. Joseph, MO
http://www.ponyexpress.net/~ewelch

Police tagline.  Do not cross.