Mirroring Eds thoughts...
I'm thinking that the long tab of the arm from the diaphragm mech is
riding near the end of the arm coming from the rear mount. They slide
over each other throughout focus travel from infinity to 1:2. If one of
those is slightly bent, it can slide off the other. At 1:2 (full
extension), a slight bend (little error at infinity) will display the
most error in alignment. The repair shop in Italy said "you can't use
this lens on that adapter". NOT SO. The adapter can only push the tab
on the back of the lens so far, and that can be duplicated by hand.
___________________________________
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
On 6/21/2011 5:09 PM, Chuck Norcutt wrote:
> When he's focusing to a small aperture he's putting the lens's diaphragm
> lever hard up against the fixed position diaphragm control pin on the
> adapter. If that is bent or otherwise mispositioned it could be putting
> a lot of stress on the lens's diaphragm lever as it tries to push the
> pin back to the position where it should be.
>
> I have no idea what sort of problem that might cause in the lens but I
> don't think it's good, especially if the user has a heavy hand. I don't
> think you can diagnose the problem without the particular adapter that
> he's using. The reason you may not see the problem is that the problem
> may be caused by that specific adapter.
>
> Chuck Norcutt
>
>
> On 6/21/2011 4:17 PM, John Hermanson wrote:
>> Thanks for the input. Yes, I'd guess that Olympus version of the
>> adapter would have steel front mount, might as well be from OM-1.
>>
>> Why I asked: a new customer is using his 90mm f2 Zuiko on an m43
>> adapter. He says that when the lens is focused all the way out to 1:2,
>> he stops the lens down to any small aperture and then hears a "click"
>> inside the lens. When the lens is focused back, the diaphragm ring
>> turns, but stop down button / tab on back of lens are no longer linked
>> to the diaphragm. Customer is in France, lens has been to a repair shop
>> in Italy several times, now I have it. I wanted to see if m43 adapter
>> could be linked to this problem in any way, but all it's doing is
>> holding the lens stopped down.
>>
>> So far, lens is not misbehaving, DAMN, I wish it would. I like it when
>> the problem is cut and dried.
>>
>> Again thank you for all the responses.
--
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