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RE: [OM] Cleaning an OM300/4.5 lens

Subject: RE: [OM] Cleaning an OM300/4.5 lens
From: Olaf Greve <Ogreve@xxxxxxx>
Date: Wed, 31 Mar 1999 14:33:20 +0200
Cc: "'tom@xxxxxxxxxxxx'" <tom@xxxxxxxxxxxx>
Hi, 

It seems like you are the one to talk to, as you have gone through the
process of cleaning an OM300. Today I inquired over here and it seems like
the cost for having it cleaned will end up between $80 - $100. As it seems
that it should not be too difficult to clean it (I hope and pray I'm not
mistaken here ;) ), it might merit the trouble to attempt to do it myself
(gives me an interesting chore for the easter days)...

Basically what I will need is kind of a step-by-step guideline for reaching
the element with the fungus. I have written down what I think will be the
process for doing so, can you please answer the specific questions I ask
along the path?

I have sent this message to you both directly and via the list (so others
can also add on to it if they have any related information). Alright, here
goes:

>grasp with the left hand the ring at the base of the hood, and with the
>right the hood itself. Then rotate the hands as if you were unscrewing
>something (that's really happening).

Yesterday Frank van Lindert suggested me the same approach, I tried it and
it easily unscrews. That is as far as I have gone so far (i.e. I didn't
remove the shade from the lens, I just unscrewed it). I suppose the shade
hood can then simply be removed by pulling it off?

>> You wrote that a small screwdriver should suffice and that no spanners
are
>> needed, from the looks, the fungus is only present on the top of the 2nd
>> element. Fortunately the bottom of the lens doesn't seem to have any
fungus.
>> Are you sure that a small screwdriver is all that is needed to reach that
>> part?

>generally the most exposed part is that is removable as described. If the
>second element and not *group* is really in question, you are right you
need
>a wrench.

Hmmm, basically what I am referring to is when you look into the lens from
the front, you will see the front element (i.e. the first "lens", this is
what I meant with the word "element") and some 4-5 centimetres below that
you see the second one, the latter one is the one with the fungus.

Now, for the rest of the process (i.e. after removing the shade hood):

For removing the "lens info ring" which holds the first element in place
(i.e. the "inside" of the filter ring, where it mentions stuff like: "MC
300mm Olympus" etc.), Frank suggested to use a rubber ring of the same size
to evenly apply pressure and prevent shooting out over the lens with a sharp
tool. This idea is clear, however two small questions:
1-Do I first have to remove the screws you mentioned (i.e. the ones that are
located under the shade hood)?
2-When removing these screws, what happens exactly (more specifically, will
the complete housing be loosened, or will something fall apart, or...?!?)?

After this ring has been removed, I guess the first element is completely
loose and can be removed, right? If this is the case, and I remove the first
element, will there be any awkward pieces coming loose, or are there any
other things I should take particular care with?

After removing the first element, I assume the second element is directly
reachable for cleaning. Preferrably I would like to leave this element in
place and clean it like that (without having to remove it). Do you see any
issues with doing that?

>Here John Hermanson only can give the best advice. Generally speaking, i
>clean lenses this way: I alitate on the lens and dry with a clean cotton
>wrap. If this is not enough, I wet the cotton towel with alcohol. If this
is
>not enough again, I use propylic alcohol (isopropanol) that is used also
for
>circuits. If the lens is "dirty dirty", I use a bit of ammonia (most glass
>cleaners are ammonia. Mirrors-makers clean the glass with ammonia, too). I
>am speaking of the exterior of lenses, of course. For the interior, a
>dust-free room is advised.

O.k., I have heard that Pond's cream may not be available in The
Netherlands, so maybe I have to go for one of the things you mentioned. Do
you know if any of these substances can damage the coating (FYI: my lens is
a multi-coated version)?

Well, supposing the cleaning process goes as described above, there will be
a few potential pitfalls left:
-Getting a dust-free environment;
-Re-assembly of the lens;
-???.

If you have any advise on these, it would also be more than welcome,
especially considering the re-assembly of the lens, is that a
straightforward process, or is it tricky with having to align all sorts of
things before screwing it back together, etc.?

>> Cheers, and let's see if can get this thing cleaned. :)

>Yes, it deserves it.

That's why I'm willing to make the effort :)

Cheers!
Olaf

PS: feel free to directly e-mail me if you think this discussion is getting
too lengthy for the list, also, if you still have the messages left from
your original question (which must have been some 8 weeks ago now), I'd love
to see them...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Olaf Greve
 /\/\   Cambridge Technology Partners, Inc.
/ /_ \  Apollo House,   Phone:  XX-31-(0)20-5750419
\  / /  Apollolaan 15,  Fax:    XX-31-(0)20-5750500
 \/\/   1077 AB,        E-mail: ogreve@xxxxxxx
        Amsterdam,      http://www.ctp.com
        The Netherlands
        Personal: http://www.angelfire.com/ca/greve
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



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