Thanks again, again. My guess is that you've never seen this particular
malady before, eh?
Chuck Norcutt
John Hermanson wrote:
> excellent!
>
> ___________________________________
> John Hermanson
> Camtech Photo Services, Inc.
> 21 South Lane, Huntington NY 11743
> 631-424-2121 | Olympus OM Service since 1977
> http://www.zuiko.com | omtech1 AT verizon.net
>
>
> Chuck Norcutt wrote:
>
>>Thanks for the help. The problem is fixed. The lens must have been
>>repaired and mis-assembled some time before I got it and apparently I've
>>never tried to use it until recently or, if I did, never attempted to
>>set it wider than f/5.6.
>>
>>The problem was that the diaphragm stop down lever driven by the camera
>>(CE1049) which is supposed to fit into the wider of two notches in
>>CE1584 was on the outside of the notch and not inside the notch. The
>>aperture control pin (CE1573) also fits into a notch in CE1584 but into
>>the smaller of the two side-by-side notches. It was properly in the
>>small notch but, since the stop down lever was outside of its own notch
>>in CE1584, when the aperture control pin would cause CE1584 to rotate
>>CE1584 would run into and jam against the misplaced stop down lever
>>before completing its full travel.
>>
>>It took removing the front lens assembly as you suggested to see what
>>the problem was but the fix had to be implemented from the back by
>>removing the mount so the stop down lever could be lifted and inserted
>>into the notch in CE1584.
>>
>>Add "mis-assembled 28/2.8" to your list of symptoms and fix file.
>>
>>I think this may be the first time I've ever "easily" removed a thread
>>locked lens assembly with a little bit of acetone.
>>
>>Thanks again for the help.
>>
>>Chuck Norcutt
>>
>>
>>
>>John Hermanson wrote:
>>
>>
>>
>>>The pin on the 28 2.8 is L shaped and connects to the diaphragm control
>>>cam through a slot in the main tube. To remove the ring, you'll have to
>>>take out the 2 screws holding the pin in. Unscrewing the front lens
>>>assembly, which would expose the diaphragm mechanism, should reveal what
>>>the problem is.
>>>
>>>___________________________________
>>>John Hermanson
>>>Camtech Photo Services, Inc.
>>>21 South Lane, Huntington NY 11743
>>>631-424-2121 | Olympus OM Service since 1977
>>>http://www.zuiko.com | omtech1 AT verizon.net
>>>
>>>
>>>Chuck Norcutt wrote:
>>>
>>>
>>>
>>>>Hey, here's a real, live, nitty-gritty, on-topic OM post!
>>>>
>>>>I have a 28mm 2.8 which will not open (using the diaphragm ring) to more
>>>>than f/5.6. The diaphragm blades open fully when the DOF preview button
>>>>is not depressed but the diaphragm ring can't be rotated to either f/4
>>>>or f/2.8. It hits a hard stop at f/5.6.
>>>>
>>>>I assumed that there must be a problem with the detent ball but was
>>>>surprised when I removed the filter/detent ring and found that the
>>>>detent mechanism is fine and there is no appreciable wear on the ring.
>>>>
>>>>I tried rotating the diaphragm ring again without the detent ring and
>>>>ball installed and it still hits a hard stop at f/5.6. Then I tried to
>>>>lift off the diaphragm ring and was surprised to discover that I
>>>>couldn't. I can lift the side opposite what I'll call the diaphragm
>>>>coupling pin (CE157300 on the parts diagram) but that pin acts like it
>>>>has a hook on the end. The pin side lifts no more than 1/2mm and stops
>>>>cold just as though what I think should be a flat bladed pin has a hook
>>>>on the end and is catching on something.
>>>>
>>>>Any suggestions? If I remove the lens mount will I be able to see the
>>>>inside of the barrel and figure out what the obstruction is? I guess I
>>>>could also remove the two screws attaching the diaphragm ring to the
>>>>coupling pin but I hate to disassemble what I don't have to.
>>>>
>>>>Thanks,
>>>>Chuck Norcutt
>>>>
>>>>
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>>
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