With great trepidation I will offer my two cents on this.
I had a problem with a 50mm lens in that the aperture was slow to
open if only closed down one stop. More than one stop and it seemed
fine.
On removal of the lens mounting ring at the rear I discovered there
is a coil spring with one end fixed to the lens body and the other
connected to a ring which is free to rotate. This ring has a tongue
which goes down into the guts and engages a forked lever which acts
upon the actual mechanism containing the diaphragm blades.
My problem proved to be an excess of friction hindering the movement
of the ring very slightly. The spring I mentioned is not
particularly strong in action. When the spring was disconnected the
aperture preview function would not operate - likewise the camera
actuated stop down - ie, the aperture would not re open when
actuated. Could it be that the lens you mention is missing an
equivalent spring, has a broken spring or one that has had one end
come adrift ?
This is just wild speculation on my part as I have no idea if the
lens you mention has a similar layout of its aperture
actuation mechanism.
By the way, lubrication was definitely not the solution as most
lubricants had too high a viscosity and served only to make matters
worse - the parts needed to be completely free of lubricants.
Giles
> Would anyone care to explain 'exactly' how the mechanism in question
> (leaves, or what nots!) works please. I'm all out to learn about
> lenses, and if someone has a few minutes of experience to spare... I'll
> LAP THEM UP!!!! :)
>
> Thanks
>
> Konrad
>
>
>
>
> Winsor Crosby wrote:
> >
> > That sounds really awful. Remember the diaphragm has to stop down and
> > release every time the shutter fires. Quickly. If there is gunk or
> > corrosion on those little individual leaves, the whole diaphragm may have
> > to be replaced. I don't know, but it doesn't sound minor to me.
> >
> > >Which lens is it... f 3.6 or f 4? If the glass is OK, I'd go for the f 3.6
> > >version (I know, I have one). I'd be more cagey if it's the f 4. It
> > >sounds
> > >like the problem is confined to the lens mount area, therefore shouldn't
> > >require major disassembly of the lens to clean/lube. I'm saying this
> > >assuming
> > >that the stop-down lever doesn't stick AT ALL.
> > >
> > >A question, though... how often do you use DOF preview? I find that I
> > >seldom
> > >use it. Just curious.
> > >
> > >M.
> > >
> > >pizzuto @ waldonet.net.mt (Konrad Pizzuto) (Mailed by: pizzuto @
> > >waldonet.net.mt (Konrad Pizzuto) @ internet)
> > >02/08/98 02:55 AM EST
> > >To: olympus@xxxxxxxxxxxxxxx @ internet
> > >cc: (bcc: Mahlon R. Haunschild)
> > >Subject: [OM] Found a 35-70 Zuiko zoom - help required!!
> > >
> > >Hi,
> > >
> > >I know of an Olympus 35-70 zuiko lens for sale in a shop in Malta, for
> > >some $90. It has a problem with the preview button however. Whilst the
> > >diaphragm moves normally when you select the separate apertures via the
> > >ring, pressing the preview button makes the little protruding 'thing'
> > >that moves stay to the 'preview' side. It does not return to its normal
> > >position when you release the button, meaning that you are, in practice,
> > >always 'depth-of-field' previewing!!! Now, do you think it is worth the
> > >money, and can I repair it myself? If not, what price might I try and
> > >negotiate? Also is that a normal price for a second hand zuiko 35-70?
> > >
> > >regards
> > >
> > >Konrad Pizzuto
> >
> > Winsor Crosby
> > Long Beach, California
> > mailto:wincros@xxxxxxxxxxx
> >
> > ##################################################################
> > # This message was delivered via the Olympus Mailing List
> > # To receive the Olympus Digest send mail to: listserv@xxxxxxxxxxxxxxx
> > # with subscribe olympus-digest in the message body.
> > #
> > # To unsubscribe from the current list send a message to
> > # listserv@xxxxxxxxxxxxxxx with unsubscribe olympus in the message body.
> > #
> > # For questions email: owner-olympus@xxxxxxxxxxxxxxx
> > ##################################################################
>
> --
> <hr>
> <a href="http://www.geocities.com/SunsetStrip/8129";>Silenthawk's
> Homepage</a>
> <a href="mailto:pizzuto@xxxxxxxxxxxxxxx";>Mail me</a>
>
> ############################################################
> | This message was delivered via the Olympus Mailing List
> | To receive the Digest version send mail to: listserv@xxxxxxxxxxxxxxx
> | with "subscribe olympus-digest" in the message body.
> | To unsubscribe from the current list send a message to
> | listserv@xxxxxxxxxxxxxxx with "unsubscribe olympus" in the body.
> | For questions email: owner-olympus@xxxxxxxxxxxxxxx
> | htttp://Zuiko.sls.bc.ca/swright/olympuslist.html
> ############################################################
>
>
>
############################################################
| This message was delivered via the Olympus Mailing List
| To receive the Digest version send mail to: listserv@xxxxxxxxxxxxxxx
| with "subscribe olympus-digest" in the message body.
| To unsubscribe from the current list send a message to
| listserv@xxxxxxxxxxxxxxx with "unsubscribe olympus" in the body.
| For questions email: owner-olympus@xxxxxxxxxxxxxxx
| htttp://Zuiko.sls.bc.ca/swright/olympuslist.html
############################################################
|