A warning that I'm overstepping my bounds here but, from looking at the
parts diagram, I would agree that it looks as though the aperture ring
should simply slide off. If the grease has solidified to the point of
preventing the ring from turning (as Mark's note hypothesized) then I
would not be at all surprised that it's that same solidified grease
that's acting as a glue between the two parts and also preventing you
from sliding it off as well as turning it.
If it were me I would very gradually feed some drops of a solvent such
as Ronsonol lighter fluid around the inner diameter of the aperture ring
and perhaps on its back face. Also maybe a drop or two in the groove
that appears to slide over the actuating pin Mark mentions. Just don't
use so much that it ends up dripping and running inside the lens.
If the grease is totally dried out and has evaporated off all of its
volatile components I'm not sure warming can help much. It probably
does need a solvent to loosen it up.
On the other hand I think this is a very expensive piece of glass... so
ignore what I just said. :-)
Chuck Norcutt
Alan Wood wrote:
> In 2001, Mark Dapoz kindly provided some advice:
>
> Chances are that the grease around the aperture ring has solidified
> and is preventing it from turning. Use a rubber stopper to twist the
> front part of the lens off, it's just a big retaining ring. The
> aperture ring should then easily come off. You will then see a
> little pin sticking out from the barrel. Try moving that pin, it
> should move freely and close the aperture. If it doesn't then you
> have other problems and it's best to get the lens CLA'd. If it does
> move freely, just clean up the grease on the aperture ring and
> re-lube it using an appropriate grease.
>
> ----------
>
> It has taken me 7 years, but I have finally managed to unscrew the
> front ring (the one that says ZUIKO MACRO etc.). Now I cannot get
> any further. The aperture ring (the first knurled ring) will not
> come off. I have tried gently warming it.
>
> Please does anyone have any suggestions for loosening it? Maybe a
> solvent?
>
> Thank you
>
> Alan Wood http://www.alanwood.net (Unicode, special characters,
> pesticide names)
>
>
> ------------------------------------------------------------------------
>
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