[Leica] Lanthanide glass?

[benedenia at gmail.com (Marty Deveney)]

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
>