on 11/13/03 12:59 PM, Wayne Culberson at waynecul@xxxxxxxxxxxxxxx wrote:
> Okay, so I replied on list again. Hey, I'm over 50, so give me a break :-)
>
> But not to waste this post - I have a Tokina ATX 28-85/3.5-4.5 that seems to
> have developed a slight lens coating problem on the inside of the front
> element, that is visible if you hold the lens at just the right angle to the
> light and your eye. So far it doesn't seem to affect the photos at all, but
> if someone had one that was fungus ridden in the rear elements, or otherwise
> broken, but had a good front element, I would be interested in it.
> Has anyone else experienced this on a lens, that can perhaps explain it
> better, or what causes it, or if it really even matters?
> Thanks,
> Wayne
Sometimes its not too hard to go inside these zoom lenses... if you want to
mess with it you might find it just needs a cleaning. Zoom lenses, because
of the sliding cam sleeves, sometimes have more lubing grease inside than
primes... and sometimes this outgasses over time (with aid from high
temperature I suspect) and deposits on lens surfaces.
Most modern (say last 30 years or so) lenses use good adhesives for bonded
lens elements, I suspect element separation is much less common with
well-made modern era lenses than for those made before ~1975 (although I
have no proof of this other than that I think that's about when the
'UV-cure' adhesives became widely used). So maybe all your zoom lens needs
is a good cleaning...?
--
Jim Brokaw
OM-'s of all sorts, and no OM-oney...
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