I'm wondering if it is to be expected that ALL
radioactive glass Zuiko's will turn yellow eventually?
As I understand the discussion so far, some people's
early lenses are yellowed, but other were spared the
problem. What would cause one Zuiko to turn yellow but
not the other one?
I would expect radioactive decay should occur in all
of them as a function of time only rather than
external things like environment or geographic region
etc. where it was kept.
Thomas
--- Kennedy McEwen <rkm@xxxxxxxxxxxxxxxxxxxx>
schrieb: > In article , Thomas Heide Clausen
<omlist@xxxxxxx>
> writes
> >
> >I read somewhere that strong UV radiation should
> make the yellowing
> >disappear. Of course, it was on a Pentax mailing
> list, and I cannot
> >find the posting claiming that. Any of you guys out
> there, skilled in
> >the issue of radioactive lenses, who can either
> debunk that or
> >confirm it as a possibility for such unfortunate
> lenses.
> >
> >55/1.2 is a cool lens otherwise, btw....
> >
> I can't fully debunk it, but I think it is unlikely,
> due to the nature
> of the problem. The yellow is damaged silicon
> compounds in the glass as
> a consequence of the radiation and I cannot see any
> way that exposure to
> UV would repair this. That said, it isn't something
> I have tried, so I
> could be wrong - I just can't visualise a mechanism
> that would make it
> work at the moment.
>
> Years ago we used to supply video cameras to the
> main UK nuclear
> reprocessing plant for monitoring systems - great
> business because every
> six months they had to replace most of the cameras
> because, amongst
> other damage, the lenses went brown - and I do mean
> brown, not pale
> yellow! If UV exposure would have cured the problem
> I am sure they
> would have found it and saved themselves a fortune.
> ;-)
> --
> Kennedy
> Yes, Socrates himself is particularly missed;
> A lovely little thinker, but a bugger when he's
> pissed.
> Python Philosophers
>
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> < Web Page:
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>
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