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Re: [OM] Tokins atx 80-200 f2.8 Zoom (long)

Subject: Re: [OM] Tokins atx 80-200 f2.8 Zoom (long)
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sat, 23 Jan 2010 17:51:18 -0500
I suspect that the lens cement has broken down chemically due to 
exposure to (?) or just old age.  15 years is probably a low estimate of 
age.  More likely 20 and possibly even older.  I'd be very surprised it 
Tokina has spares.  But it's certainly worth an inquiry.

Kiron and some other Japanese made lenses have problems with breakdown 
of the viscosity of the grease in the focusing helicoid which turns it 
into thick oil which migrates throughout the interior of the lens.  It's 
hard to find certain models that don't need to be disassembled and 
cleaned.  Some stuff just doesn't last forever.

ps: I have an AF 80-200/2.8 Tokina and I love it.  But it weighs a ton.

Chuck Norcutt


JOHN DUGGAN wrote:
> Hi all, Took my Olympus OM 4ti out for exercise yesterday. Pulled it
> out of it's case with minty Tokina ATx 80-200mm f2.8 zoom attached. 
> Since buying this lens I have really come to appreciate it and would
> be lost without it. Took a few shots, and realised that there seemed
> to be "ghosting" during focussing. Looked at the front of the lens to
> find a patch of what appeared to be fungus about 35mm in diameter in
> the front element group. The lens itself (bought from a listmember)
> about 2yrs ago is pristine! Last time I used the lens about 5 months
> ago it was fine. UK importer wants £25, $40, to look at the lens. If
> they can get spare parts it will be £60/$90 labour PLUS parts and
> tax.
> 
> I decided "nothing ventured nothing gained" and so proceeded to start
> to dismantle it! This was not as foolish as it sounds, the problem
> seemed "right at the front end" Tokina atx on e-bay seems to have
> exactly the same problem! 270516683772
> 
> Undo 3 tiny screws and front cell pops out. The front cell consists
> of a cemented doublet and a second lens. The cement of the doublet
> had softened and run, and the "fungus" was cement which had trickled
> down the rear of the element leaving filament trails and had pooled
> in the centre due to the lens being stored face down. This cleaned
> off with no problem. However the doublet now shows signs of
> de-lamination with silvery patches between the elements.
> 
> What to do next?
> 
> Hope new elements are available, and that distributor will supply me
> with one to fit myself. New distributor, lens 15? years old?
> 
> Look out for lens in Olympus fitting on e-buy and hope it does not
> have problems.
> 
> Look out for lens in other fitting and either swop front cell into my
> lens or change my lens mount onto other lens. (if lens cell is good.)
> 
> 
> Get doublet re-cemented...if I can find a firm to do this.
> 
> I cannot understand  how the doublet has de-laminated. The lens was
> in perfect condition when I bought it. I have always used a front
> filter and have NOT used lens cleaner on it. Stored in spare bedroom,
> no real exremes of temperature. Has anyone had similar experience? 
> Advice gratefully accepted. Any info on lens parts numbers would be
> VERY useful.
> 
> Regards John Duggan, Wales, UK
> 
> 
> 
-- 
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