Archived posting to the Leica Users Group, 2014/02/11

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Subject: [Leica] Lanthanide glass?
From: benedenia at gmail.com (Marty Deveney)
Date: Wed, 12 Feb 2014 07:52:04 +1030
References: <52FA0EC1.7060102@summaventures.com> <F62F2284-786F-432A-BF9F-8F2023D5CF30@bex.net>

There are better, more stable ways to make high refractive index glass.  I
think lanthanum was largely discontinued in camera lenses for these
practical reasons rather than anything to do with health.

Marty


On Tuesday, 11 February 2014, Howard Ritter <hlritter at bex.net> wrote:

> Lanthanum is mildly radioactive, but not so much so that its use in
> eyepieces for astronomical telescopes is prohibited. Several manufacturers
> advertise that their products contain lanthanum glass.
>
> --howard
>
>
> On Feb 11, 2014, at 6:51 AM, Peter Dzwig <pdzwig at 
> summaventures.com<javascript:;>>
> wrote:
>
> > Guys,
> >
> > Knowing your expertise....
> >
> > What is the issue with Lanthanum in lenses. I thought its use had been
> > discontinued long ago on health grounds, maybe in the 50s, although what
> the
> > details were I don't recall. Now someone else tells me otherwise.
> >
> > ...were there other compounds discontinued for similar reasons?
> >
> > Peter
> > --
> >
> > ===========================================================
> > Dr Peter Dzwig
> >
> >
> > _______________________________________________
> > Leica Users Group.
> > See http://leica-users.org/mailman/listinfo/lug for more information
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>


Replies: Reply from pdzwig at summaventures.com (Peter Dzwig) ([Leica] Lanthanide glass?)
In reply to: Message from pdzwig at summaventures.com (Peter Dzwig) ([Leica] Lanthanide glass?)
Message from hlritter at bex.net (Howard Ritter) ([Leica] Lanthanide glass?)