On Saturday, August 9, 2003, at 12:15 PM, Thomas Haegin wrote:
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.
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.
Enuff....
Bill Hunter
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|