I usually hold the lens up to a light and look at it with a 10x jewelers
loop at both ends. I can then see early signs of fungus.
-----Original Message-----
From: Walt Wayman [mailto:hiwayman@xxxxxxx]
Sent: Monday, April 26, 2004 10:06 AM
To: Oly List
Subject: [OM] Finding Fungus For Fun
I received an off-list e-mail inquiring about the possibility of using
the little Hakuba slide viewer that I posted about last week as a light
source for the inspection of lenses for fungus, dust, and so forth.
With only moderate verbosity, I expressed my opinion, then proceeded to
opine further about what I considered to be the proper way to check the
innards of a lens.
Then I got to wondering if my advice was as good as I thought it was
when I wrote it. Since we're all, at least those who remain true-blue
OM users, now in a position of dealing almost exclusively with used
gear, often bought sight-unseen based on a description by a total
stranger in a faraway place who may be either ignorant or dishonest, or
both, we need to know how to inspect the gear properly. It seems we're
hearing more and more about problems with lenses bought over the
internet from some in our group.
Anyway, this is what I wrote, and if anyone has any disagreement, any
correction, or a better modus operandi, I think it would benefit us all
to hear about it. I can't always be perfect, you know, and do
occasionally learn a thing or two here.
"The little Hakuba slide viewer is definitely NOT the tool you're
looking for to inspect lenses. The best way to spot nasties inside a
lens is by shining a plain old flashlight through it, from each end,
while moving the light and the lens around. Like the focused beam of
light from a slide projector shows the dust floating in the air, all of
which was invisible in the diffused room light, the focused beam of the
flashlight sharply reveals the crap inside a lens.
"As an experiment this morning, I used both the slide viewer and a
two-cell Mag-Lite to look at the only lens I have that I know has an
internal problem, a 65-200/4 Zuiko with the all-too-common bad element
toward the back. With the diffuse light from the slide viewer, had I
not known about the bad element, chances are better than good that I
would have overlooked it. With the hard light from the Mag-Lite, the
frosting of the element was immediately obvious, as
was every speck of dust inside the lens.
"In fact, using a flashlight to look inside a lens, particularly a zoom
lens, can be a scary experience. It puts me in mind of a line from an
old Rod Stewart song: "The morning sun, when it's in your face, really
shows your age." Almost every lens has at least one or two specks of
dust inside, and a hard light source, just like a projector in a dark
room or the sun on Maggie May's face, shows things that soft, diffuse
light won't."
Walt, standing by for correction
--
Everybody thinks they have a sense
of humor -- even people who don't.
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