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Re: [OM] 50/3.5 macro and 28/3.5 problems

Subject: Re: [OM] 50/3.5 macro and 28/3.5 problems
From: Nils Frohberg <nilsf@xxxxxxx>
Date: Mon, 17 Jun 2002 03:03:39 +0200
* dreammoose <dreammoose@xxxxxxxxx> [020617 01:31]:
> Welcome to the list, Nils. What, yo never call or write unless you're in 
> trouble? ;-)

i'm slowly starting to get my gear together. i ran around with the OM1
and a 50/1.8 for quite some years now, until the light meter broke. now
a short while ago, my dad gave me the rest of his equipment (thanks
again, dad :), which included the OM2 and some lenses. as soon as i got
all set up, i'll bug all of you with my pictures :)

btw, does anyone on the list know a good repair shop in germany (at
best, bonn/cologne area)? i think i should get the two bodies checked.

> 
> First of all, it's not 'just a 50mm'.  The multicoated 50/3.5 is an 
> excellent macro lens. In nice condition they usually sell for US$125-175 
> on *Bay.

thanks for the info, that's what i somehow expected.

> 
> The 50/3.5 has a sticky diaphram. This is commonly caused by a dirty or 
> bent mechanism in the back under the lens mount, oil on the actuating 
> mechanism and/or oil on the blades. I've never worked on this particular 
> lens, but all I've opened up are similar. It's probably worth while to 
> take off the rear mount (3 cross-point screws) and take a look at the 
> rear mechanism. I should be obvious how the DOF button pushes on a long 
> curved lever which moves a pin, the other end of which goes down into 
> the lens to actuate the diaphram mechanism.The spring that pulls the 
> diaphram open is there too and  has been known to come loose. If that 
> all works smoothly, but the blades don't move, it all depends on your 
> skill with small mechanical mechanisms, tools available and courage. It 
> is possible to clean these up yourself, if you are adept at that sort of 
> thing. These instructions for the 50/1.8 should give you a general idea 
> of what is involved 
> <http://olympus.dementia.org/Hardware/50mm_cleaning.html> . Even if you 
> don't want to work on it yourself, having it cleaned and adjusted is 
> probably worthwhile for this lens if the glass is all unmarked..

yes, this sounds good. i'll check first thing tomorrow morning.

> 
> On the 28/3.5, you have lost or displaced the aperture detent ball 
> bearing. If you look on the back of the aperture setting ring, you will 
> see small depressions underneath the aperture markings on the front.  In 
> the lens below where these depressions lie, there is a small hole which 
> should contain a spring with a small ball bearing on top of it. The 
> bearing pressing against the setting ring and dropping into the 
> depressions is what provides the click stops. If the ball bearing (and 
> spring) fell out of place into the lens proper, you may be able to find 
> and replace them in proper position (and replace the gucky, dried up 
> grease for smoother action). Playing hide and seek with tiny parts on 
> the rug/floor and all over an untidy desk is always such fun. The lens 
> will work fine without the ball bearing and spring, it just has no 
> detent action. Some people who are intent on setting exact apertures 
> intentionally weaken or remove the detent action.

the ball's actually still in place, the metal ring that covers the ball
is not pressed down completely though (making the clicks when the ball
jumps into place). that's because the filter winds into one part of the
lens, and the part with the writing winds into another, and they don't
match exactly. i'll try to take a picture or two tomorrow illustrating
that.

but i also think this will not interfere much with taking pictures.

> 
> Moose

thanks,
--nils

-- 
Nils Frohberg
GPG Key: email nilsf@xxxxxxx with Subject: GET GPG KEY
GPG Key: http://www.nils-frohberg.de/gpgpub.txt

"The truth is, that those who have never entered upon scientific pursuits
 know not a tithe about the poetry by which they are surrounded."
                                                       -- Herbert Spencer

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