>..and, more
>germane to this list, the Zuiko's diaphragm sticks.
>
>The lens is in gorgeous shape. It's not quite a 10, but only because a few
>of the ridges on the aperture ring are shiny at the very front corner. The
>glass is clean and mark-free, the focus and aperture turn easily, and it
>came with a Vivitar UV filter that looks like it was installed when the lens
>was purchased and never removed.
>
>The problem is that the diaphragm, which closes down easily and snappily
>enough, takes a second or so to open up all the way from f/22. There's no
>oil visible on the blades, and the stopdown lever takes no more effort to
>operate than normal. If I turn the aperture ring quickly from f/2.8 to f/22,
>the diaphragm follows it a bit, stopping down to f/4 or so, before opening
>up again.
>
>Is this something that I'd be nuts to think about trying to fix myself? Is
>it a common problem? Should I send it back and say "you sold me a bum lens"?
>Do I count myself fortunate that I only spent $70 on it, and live with it?
>
This is an unbelievable similarity to my situation. I just got a like new 50mm
F1.4 Zuiko off Ebay -- the serial number is over 1,000,000 -- that had the same
problem -- sticky diaphragm. It would shut down OK and usually open OK but
if you used the stop down button it usually didn't open back up very quickly.
I was able to fix the problem myself just last saturday night.
I took the lens mount off -- 3 screws.
I then removed the stop down button and lens release button -- they just lift
out.
I then unscrewed 3 screws that hold on what I would describe as a retaining
plate.
Underneath the retaining plate are 2 rings that "kinda" rotate over one anothe.
Each
ring has two projections: 1 going down into the lens engaging a notch and 1
coming back
up "sticking" out of the mount face of the lens.
One of these rings is for the aperture ring. It engages the aperture ring with
the
projection that goes down toward the aperture ring. The projection that sticks
out of
the mount plate is the projection you see move on the lens mount when you
rotate the aperture ring.
The other ring engages the diaphragm. The projection that goes down engages
the diaphragm and the one that goes up out of the lens mount is the lever that
is "hit" by the camera when the shutter is released and the lens briefly
"stops down" to its preset aperture.
Anyway, these 2 rings as I said rotate over one another. In taking mine apart I
found one small spot of what looked like grease -- evidently from the focusing
helix. I merely cleaned the 2 rings very well and reassembled in reverse order.
You do need to be careful of the diaphragm "return" spring, which attaches to
the ring for the diaphragm and the retaining plate.
The lens now has a very "snappy" diaphragm just like all my other lenses.
I guess what this means is that if you are reasonably mechanically inclined
you might want to try this yourself. I'm not sure I would have wanted to get
any deeper into the lens, however. Also, none of the optics had to be removed
to do this fix.
Let the list know how it turns out.
Mark Hammons
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