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Re: [OM] Helicoid grease (was:50/2 macro vs. 90/2 macro)

Subject: Re: [OM] Helicoid grease (was:50/2 macro vs. 90/2 macro)
From: "John Hermanson" <omtech@xxxxxxxxx>
Date: Mon, 8 Jan 2001 09:07:11 -0500
Most loose helicoids are either replaced due to extreme use or regreased.
That's it for tightening a helicoid.
If you take the helicoid apart, be sure to mark the points where the tubes
disengage from each other.  They can thread back together in multiple
positions and if you don't start with the ONE correct position,   the levers
in the back will not line up with the correct position on the mount.

John  Hermanson
___________________________________
Camtech, Olympus Service since 1977.
21 South Lane,  Huntington NY 11743-4714
631-424-2121 http://www.zuiko.com
Free Olympus Manuals: 1-800-221-3000
___________________________________
----- Original Message -----
From: "Lex Jenkins" <lexjenkins@xxxxxxxxxxx>
To: <hopi@xxxxxxxxxx>
Cc: <olympus@xxxxxxxxxxxxxxx>
Sent: Sunday, January 07, 2001 11:21 PM
Subject: Re: [OM] Helicoid grease (was:50/2 macro vs. 90/2 macro)


| Hiya,
|
| I suspect a helicoid tensioner is a jig to restore mechanical fit in a
worn
| helicoid.  I don't see anything in the focusing mechanism itself that can
| either be replaced or adjusted.
|
| My guess is the helicoid tensioner either: peens or otherwise modifies the
| threads very slightly to restore close tolerances; stretches the outer
| diameter of the male-threaded section; or, reduces the outer diamter of
the
| female-threaded section.  Probably the first.  Probably not something the
| average tinkerer could duplicate.
|
| Also, regarding complete disassembly of the lens, it appears to me that
| keyed wrenches are necessary to remove lockrings retaining optical
elements
| just beneath the filter ring and just above the diaphragm.  These
lockrings
| either fit snugly or are secured with threadlocker compound.  Can't get
'em
| loose with just a screwdriver.
|
| I've fabricated keyed wrenches using leftover brass door keys and brass
| stock from the hardware store.  A major hassle but sometimes the only way
to
| do a job right.
|
| I can see some definite complications in the Zuikos that I haven't run
| across in other lenses:
|
| 1. The checkered rubber ring that must be removed to access the screws
| retaining the focus shroud.  In most lenses the checkered focus ring is
part
| of the shroud, eliminating one disassembly/reassembly step;
|
| 2. Some optical elements are not permanently mounted in metal or plastic
| collars, making careful handling far more important - not only to avoid
| fingerprints that might mar the coating, but I suspect that fungus, mold
or
| mildew can be transferred to the elements through touch.  It's probably a
| good idea to wear latex or thin vinyl gloves while handling the optical
| elements.
|
| OTOH, Zuikos eliminate a couple of disassembly complications present in
| Canon FD lenses:
|
| 1. It isn't necessary to disassemble practically the entire damn mount
when
| going through the rear;
|
| 2. The filter ring shroud (the doodad with the lens info printed on it)
can
| easily be removed using a screwdriver.  Some other lenses don't have keyed
| slots, making it necessary to use grippy rubber tipped tools to loosen
those
| rings.
|
| Regarding fungus, mold and mildew removal, I'm experimenting with a couple
| of household cleaners like Oxy-Clean, an oxidizing cleanser that doesn't
| contain common bleach (sodium hypochlorite).  I'll report back whether it
| helps, harms or does nothing.
|



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