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Re: Yellowing of radioactive lens elements....Re: [OM] 55/1.2

Subject: Re: Yellowing of radioactive lens elements....Re: [OM] 55/1.2
From: Thomas Haegin <haegint@xxxxxxxxx>
Date: Sun, 10 Aug 2003 01:10:53 +0200 (CEST)
Bill,
I could certainly understand if you are getting fed up
with the issue and just pass now. But I would much
appreciate if you found time and energy to elaborate.
I personally find this discourse extremely
interesting, and I'd be happy to get educated. I would
hope other members of the list felt likewise.

So you are esseantially saying that the radioactive
rare elements were not used as ingredient in the Zuiko
glass "recipe", but only in the surface coatings? I
previously thought these elements were used to
"enrich" the "glass soup" in order to achieve the
whatever superior glass qualities required for 1.2 and
1.4... but yeah, I sure could be wrong.

And if these elements are in the coatings only, and
were used in MC coatings rather than in SC coatings,
why do the early 1.2 and 1.4 yellow as they were all
SC in the beginning anyway? Or did they have some
"special" SC coating formula?

Thomas


--- whunter <whunterjr@xxxxxxxx> schrieb: > 
> Ahhhhh Ha......   Exactly!!!!    Just posted re this
> fundamental issue. 
>   ONE:  degradation is primarily in the organic
> binder substrates of the 
> coating NOT the inorganic matrix of the glass.  TWO:
>  whether induced 
> by ionizing radiation of 'radioactive decay', HEAT,
> cosmic radiation, 
> etc., you see the effects of degradation in the same
> end results.  
> Given a constant level of ionizing radiation (UV,
> radioactive, cosmic, 
> visible light spectrum, whatever......) the
> degradation rate of the 
> coating will vary greatly depending on ambient
> temperature AND 
> HUMIDITY. All of this is additive.  As you
> appropriately remind, the 
> differing degradation of the same lens reflects
> changes in additive 
> contributions from the environment.  Further, since
> the exterior of the 
> lens ( the coating surface) has greatest exposure,
> virtually all of the 
> observed changes are limited to that molecular
> level, NOT the glass.


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