I have seen sticky focus ring on this type of lens several times. The
tolerances on the fit between the ring and inner barrel are very tight.
Just a little dirt or spilled drink between the edges of the front or
back edge of the focus ring can eventually gum it up. No impact
required. I don't think anyone had ever opened this one.
___________________________________
John Hermanson | CPS, Inc.
21 South Ln., Huntington NY 11743
631-424-2121 | www.zuiko.com
Olympus OM Service since 1977
Gallery: www.zuiko.com/album/index.html
Daniel Sepke wrote:
> If it has recently been purchased with known, or undisclosed faults (the
> sticky focus issue) it may have been subject to an unskilled botched repair
> attempt by the seller. I know the 250mm I had for a few hours had been
> abused prior to my owning it. Cambridge had not disclosed any of the issues
> with that lens in their sale listing. If the scarcity of this lens is
> accurate who knows the one John has been asked to work on may be the same
> one I had.
>
> The sticky focus problem could be due to a drop that put the focus ring
> slightly out of round perhaps or it could have shifted the internal
> mechanism somehow, remember this lens has close focus correction that moves
> the internal groups as the lens focus' closer. Element reversal is a very
> real possibility if an unskilled repair person was in the lens. Either way
> it is likely a sad thought that this lens is probably never going to be
> repaired either due to parts unavailability or fear of damaging it further.
> If I was in John's shoes I know I would be reluctant to do much with it.
>
> Dan.
>
> -----Original Message-----
> From: Dawid Loubser
> Subject: Re: [OM] Separated Zuiko 250/2, was: Inside the Zuiko 300mm F4.5
>
> Hmm - that's quite a plausible theory from an optics point of view,
> would explain
> why it could be sharp in the centre (where it never matters which way
> around the elements
> are mounted, except for coating differences and as long as the order
> is maintained) and
> go all screwy in the corners.
>
> Usually element separation is plainly visible.
>
> On the other hand, I wonder who would have the guts to take a 250/2.0
> apart without him
> knowing *exactly* what he was doing. Even our on-list genius John
> seems scared to take
> on this problem :-)
>
--
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