Hello Omympoids,
The recent threads on fungus (pun intended ;) ) have been very interesting.
I did a bit of research about this organism, and have read that most fungus
is very host specific, and is also very sensitice to environement. They
require fairly specific growing surfaces, this is probably why we usuually
only see the thread type fungus on lenses. I have read that funguses can
only survive within certain temperature ranges too, in fact the reference I
saw said that common fungi cannot survive below 5C or above 50C, Humidity
also plays a strong part in fungi survivablity.
After reading this I tried DEEP freezing my 135mm lense for a few days in a
sealed bag with some silica gel at about -18C. Hopefully this will have
killed off any remaing fungi. To me this seems more reliable than the UV
treatment as there are no hidden or shaded area of fungi.
Any fungi-ologists ;) on this list who can comment on this...
Stuart
--- Begin Message ---
|
Subject: |
Re: [OM] Fungus again |
|
From: |
"Thomas H. Hogan" <flzhgn@xxxxxxxxxxxxx> |
|
Date: |
04 May 98 00:44:01 |
What happened to the suggestion of using Pond's Cold Cream followed
by methanol? This method sounds the safest (for the lens).
Although the Ultra Violet light exposure will probably be brief -- I
have
used UV (Sylvania 15 watt mercury/fluorescent tube) inside incubators
for 12 hours without seeing any notable effects on the glass door. It
should be pointed out that UV light can effect the electron orbitals
of the silicon atoms in the glass and cause it to become permanently
colored.
The glass of these mercury lamps becomes yellow with age and this effect
may partially be due to the UV irradiation.
This effect I believe comes from "two-photon" absorption and is often
seen
with old glass that has been exposed to direct sunlight for a few years.
Glass is also used in some types of radiation dosimetry gauges.
Still, it depends on the intensity of the source: I have had a glass
test
tube turn yellow inside a gamma ray (cobalt 60) source after five
minutes
of exposure! I continued to use the same test tube (containing a
compound
that I needed to sterilize) and it eventually became an opaque dark
amber.
Well, I'll close by saying that I would not subject my Zuiko lenses to
UV germicidal lamps even if I could protect or replace the rubber or
plastic parts. We also haven't considered whether or not the UV light
would have any detrimental effect on the precious single or
multicoatings!
I would consult with John H. or send them to him for proper care!
IMHO, it would be a horrible waste of a Zuiko to treat it with UV light
(for more than a few minutes)!
--
Hank Hogan --
BTW, I'm looking for a job as a biological science research
technician. If you know of anyone who might need a technician
with my skills (see resume on my home page) please let me know.
--
Thomas ?Hank? Hogan
Biologist, Photographer, Web Designer
mailto:flzhgn@xxxxxxxxxxxxx
http://www.netcom.com/~flzhgn/indexc.htm
< 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 >
--- End Message ---
|