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[OM] 100mm f2.8 Internals

Subject: [OM] 100mm f2.8 Internals
From: "Stuart Goggin" <SGOGGIN@xxxxxxxxxxxxx>
Date: 22 May 98 09:49:41 +1000
Hello All Olympus people, especially thow who have stripped down a 100
f2.8.....





I have a problem with a 100mm f2.8.   This lense is so beat up that it is
not worth fixing,  but it also happens to be my favourite lense at the
moment.    The  first problem is that the stop down linkage of the lense has
some binding, the second is that the aperature linkage seems to be
introducing a 1 stop overexposure.   For example I mounted a camera on a
tripod and measured the exposure,   I then mounted another couple of
different lenses and found that these all appeared to be more "open" by
about one stop.   

The binding appears to be much worse when I use the camera with the a motor
drive,  ie after a while it just stays stopped down.....



QUESTION 1:
I have noticed there is appreciable "Slackness" in the aperature linkage ie
the one that links the fstop ring to the camera, and I wondered if it is in
fact adjustable?

QUESTION 2:
I have stripped down the lense as far as removing the three screws on the
mount to gain access to the stop down lever.  This was so that I could
"Reconnect" the stop down linkage.  This allowed me to remove the entire
silver mount complete with the linkages.    Inside there are three screws
which appear to hold a black disk,  this hides the aperature blade linkages.
  Because there is some binding in the blade linkages I would like to remove
these three screws and see If I can clean it up and enable it to move
freely.   Will it EXPLODE into a million peices if I remove these three
screws.  Is there a better way of getting at the blade linkages......

QUESTION 3:
I am using this lense on an OM20 body,  I have noticed that the the
aperature ring on the lense when mounted on the body will move very freely
in one direction but is very stiff in the other.   It appears that the
variable resistor ring that it drives in the body may have some binding.  Is
this a terminal problem?  Easily fixed??????


Thanks for any advice.  
I tried to talk to our local authorised service centre.   But they wanted
$20 for two screws for a motor drive,  I hate to think what they would
charge for fixing this.....  As I got the lense for free as a Junk lense, it
is really not worth paying much money to fix,  but it is the "neatest" zuiko
I have, I am really impressed with the image quality I get from it, in spite
of the many many scratches on the glass.





Stuart Goggin

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