The good lens is now back together minus the oil.
I only opened it as far as the levers in the back where the mechanicals are
still a reasonable size.
It now shuts right down with the preview button and is lovely and free to
spring open again.
The other lens with the sticking iris has taken loads of fantastic pictures
in the past even though there are some sizeable dust particals inside. Does
this not matter?
Rob
----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Wednesday, January 19, 2005 9:01 PM
Subject: [OM] Re: Oil Free?
> robert smith wrote:
>
> >My question is:
> >When people say that a lens is oil free are they just refering to the
iris area?
> >
> Probably, as that is all one can see without opening the lens up as you
> have done. However, there should be no oil anywhere at all in the lens.
> What happens with age, probably dependent on the ambient temperature
> over that age and perhaps the particular batch of grease used, is that
> the grease in the may helicoid break down, releasing a lower viscosity
> fraction - oil. This then may migrate to the diaphram mechanism and/or
> the levers in the back. This problem is MUCH more prevelent in the
> design labeled 'MC', although I've seen it in 1 miJ lens with an
> earlyish serial number for that design. Whether the lach of a problem in
> later serial # miJs is a real improvement or just that they are younger
> I don't know. Uncommon in older F.ZUIKOs, whether due to better grease
> or the different mechanical design. Unfortunately, they aren't optically
> as good.
>
> >My good lens has light oil around the flat disc like levers at the back
of the lens but none further in, just white grease on the scrolls at the
side.
> >Should I remove the oil from the disc like levers before I reasemble the
lens to leave it all dry?
> >
> Yes, it should be dry there. In fact, that may be the whole problem. Oil
> on those large flat surfaces adds a lot of friction to the DOF setup.
>
> Moose
>
>
>
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