Re: [Leica] Radioactive lenses

[Edward Meyers <aghalide@panix.com>]

On Sun, 1 Aug 1999 TDSatty@aol.com wrote:

> <<<<<Hold your LTM Summicron over a white piece of paper and look through it. 
>  If 
> the lens has a yellowish cast, this is most certainly one of the early 
> Summicrons in which radioactive thorium was one of the "rare" earth elements 
> used in making the glass.  Apparently, this warm yellowish cast is part of 
> the decaying process of the thorium.  The radioactivity can actually be 
> measured with a Geiger counter.  I don't think its hazardous to your health, 
> but it may fog film over time.  And it will certainly impart a warmish look 
> to your pictures.>>>>
> 
> I hear that the radiation is a primary source of "Bokeh" in older lenses, 
> enhancing shadow detail (highlight detail in transparencies) by a process 
> similar to pre-exposure, although not recommended for users still in their 
> child bearing years, especially if a long strap is used.  Care should also be 
> taken to only lift the camera to the eye at the moment of exposure.  However, 
> there are no known studies of illness related to ionizing radiation among 
> Leica users.
> 
> Tom Schofield
> 
According to a source who got this from the Leitz family, LEITZ
never used radioactive glass, not neccessarily for the safety of the
public (there really is no problem here) but for the safety of
their workers. My source told me that this is absolute. I have
a taped interview to this. Ed