The response depends on the particular version/type of lens you have. If your
lens is one with a "two tone" rear mount (i.e., bright chrome mount attached to
a lighter frosted silver ring in the back), the trouble is relatively easy to
address. This design is known for it's tendancy for helicoid lube to migrate
into the aperture levers inside the rear of the lens, then into the ring that
operates the aperture blades, finally onto the blades themselves. Fortunately,
this design, in whatever variety (50mm 1.8, 28mm 2.8, etc.), can be disassembled
and cleaned fairly quickly if you know what you're doing.
The only other standard/wide lens with a solid mount (not those with a "two
tone" mount) that seems to have an occasional problem like this is the 50mm
1.4. Sometimes a sluggish aperture can be cured by removing the rings inside
the rear end of the lens, but often the lubrication is on the blades as well.
Unfortunately, the front elements of these lenses are sometimes impossible to
remove -- it appears that someone was overly generous with the thread lock
around the front groups, and they just will NOT unscrew! We've learned over the
years to "cut our losses" once reasonable efforts to open them have proven
unsuccessful.
Andy Gilbert wrote:
> ***Original Message***
> Date: Tue, 12 Mar 2002 02:18:57 -0400
> From: Andrew Dacey <frugal@xxxxxxxxxxxxxxx>
> Subject: [OM] Slow aperture on 50/1.8
>
> Well when I was doing a gear check recently, I found a nasty surprise, the
> aperture on my 50/1.8 seems slow. It still seems to close quickly so I don't
> think that will be an issue but on opening, it opens very slowly. Is this
> something to be concerned with? Is it fixable? Should I just use this as an
> excuse to start a hunt for a MIJ >1,100,000?
>
> - --
> Andrew "Frugal" Dacey
>
> I've got the same problem on a 28/2.8, which I had hoped to trade in for a
> 28/2. (I still bought the 28/2 ;) Comparing it to other lenses it feels
> like a spring has broken/come adrift in the stop down mechanism, when you
> operate the stop down lever on the lens, that is. Maybe John H can advise?
> (Hi, John ;) ) I doubt it would be economical to fix, especially on a
> 50/1.8. They make a good loupe, however ;) I was disappointed not to get
> rid of mine, I hadn't noticed the fault, but don't see it as a great problem
> on a landscape lens. I also thought it could be used with my rather beaten
> up OM40(PC) on those occasions where I want to take a camera, but need to
> accept it's loss/theft/damage.
>
> Andy Gilbert
> Exeter
> Devon
> England
>
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