The reply depends somewhat on which version 50mm you've got and exactly
_where_ the fungus is.
_IF_ it's the style with the two-tone mount (serial number and/or "Made
in Japan" on the mount, not around the front), _and_ you can tell that
the fungus is directly behind the front element (not deeper within),
you're out of luck. On these versions, the whole front group is a
self-contained assembly which cannot be disassembled -- you won't be
able to "open" it to get to the fungus.
_IF_ however you have this type and the fungus is deeper inside, you've
got hope. To get inside, note that the "name ring" on the front is
rather soft plastic -- be careful however you decide to remove it (see
below). Underneath are three screws holding on the front group -- easy
to open. Some versions have a small detent ball and spring underneath
-- watch out!
(The rubber stopper (from another reply) is a good idea, but most often
we just use our heavy duty tweezers spread wide enought to fit the
notches, especially with the plastic name rings. It's quite difficult
to exert enough pressure with the stopper to turn the plastic ring
without causing it to cross-thread.)
_IF_ you have an older type lens with the serial number on the front,
and the fungus is only behind the front element, you _may_ be able to
unscrew just the retaining ring that holds the front element without
having to take anything else apart. A rubber stopper will be great for
this, or even a square of rubber cut from an old inner tube. On some
versions you may have to remove the name ring before you can unscrew the
retaining ring holding the front element, but once again, this will save
alot of effort if the fungus is only behind the front element.
_IF_ you have an older type with serial number on the front, _and_ the
fungus is deeper inside, you'll have to remove the whole front group.
The "name ring" will be metal, so use either a rubber stopper or
spanners of some sort to unscrew it. Once you've got the name ring off,
the filter ring, a detent ring, and the aperture ring will come off --
but watch out for the small detent ball loose under the detent ring!
Then you can unscrew the front group. Hopefully it will be a type with
notches -- if not, it's very difficult to remove with anything but a
special tool olympus made just for this.
___OR___
If you can't get in through the front (and the fungus is not behind the
front element alone), you can always try to go in through the back and
clean the rear element of the front group from behind -- but that's much
more involved!
Tom Murphy wrote:
> I have a 50 mm lens with fungus on the inner elements. From reading the
> archives it seems that "Pond's Cold Cream" and a de greaser is the way to
> go. My problem is how do I dismantle the lens to get at the fungus?
< 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 >
|