>Hi all
>
>have just picked up a Zuiko 55mm F1.2 this afternoon by mail order off the
>web, in what seemed like pretty nice condition. Glass is perfect, some wear
>apparent on front of aperture ring, but my main concern is what may be a
>"sticking diaphragm". I have never seen this condition before, so I'm not
>sure if this is what it is, or even if it is a problem.
>
>When I use the dof preview button (with lens on or off camera) the aperture
>blades seem to close down as per normal, but when I release the dof, the
>blades don't "snap" back as quickly as on my other lenses. They do retract
>smoothly, but slowly. With aperture at f16 and shutter speed set to 1/1000
>on my OM-1n the stop down phase is too fast to see, but after the mirror
>has dropped, the blades can be seen retracting.
>
>Does the fact that the sluggish aperture retraction is occurring *after*
>exposure has been made mean that there isn't going to be any problems with
>exposure (that's what I would think logically anyway) .
>
>I found a related thread on the list from a couple of months back that
>suggested that it is possible to dismantle a lens and remove oil which
>could be the cause, but I would be a bit nervous about this in case I
>couldn't get mine back together again! Lenses like this one don't appear
>too often in Aust.
>
Peter,
I was probably the one who's post you read from a few months ago about
doing the lens surgery. It may be good for John H. to chime in here about
the relative difficulty of a "handman" fixing THIS lens but I found fixing my
Mint 50mm F1.4, which I had just gotten off Ebay, challenging, but not scary.
I say this if the problem is the same one I had. My problem was as small
patch of oil/grease between the 2 "rings" inside the lens that rotate over
each other. One ring is attached to the aperture control and the other is
attached to the actual aperture blades (Iris). If the 55mm F1.2 is the same
as the 50mm F1.4 then you DONT have to actually dismantle any of the optics
(elements) to get at and clean the rings. If the problem is oil/greas on the
aperture blades I don't know how difficult that would be but I imagine you
would have to remove some of the lens elements.
John H.?? Could you give advice on this?
Mark Hammons
P.S. Peter -- if you make the attempt let the list know how it turns out. We
all
like to know how fellow members do with their "minor surgeries". :-)
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