Olympus Zuiko 200mm f5 Disassembly Question

[r_a_feldman]

I just got a OM-1 F-Zuiko 200mm f5 (not f4!) lens (serial number 120xxx) with a known fungus condition. The infection did not look too bad and the price was right.

I have been able to remove the rear two lens elements (behind the diaphragm) and the front element, but I am having trouble getting out the next two lens groups, the doublet and the plano-concave lens in front of the diaphragm. From the exploded parts diagram that is online it looks like the only thing holding the lens group in is a retaining ring which is about 1cm wide. It looks like the ring might have some thread lock applied, so I have been soaking it in acetone, without success so far (half a day).

Does anyone have any experience with this lens and any suggestions as to how to proceed?

 

[OAPOli]

Olympus lenses are notorious for their nasty threadlocker. Acetone is good but you might need a custom tool (i.e very rigid) for the retaining ting.

 

[ic-racer]

Try harder. (seriously)

 

[r_a_feldman]

Try harder. (seriously)

I did, and only succeeded in bending the tip of my spanner wrench.

Olympus lenses are notorious for their nasty threadlocker. Acetone is good but you might need a custom tool (i.e very rigid) for the retaining ting.

What I would like now is a pneumatic impact spanner wrench.

I am going to continue soaking the ring in acetone for several days more before I try again to loosen the ring.

 

[mshchem]

 

[r_a_feldman]

@mshchem,

Good one.

That is probably what I need, but I can get two good Zuiko 200mm f5 lenses for what it costs.

 

[mshchem]

Would warmth help? Warm acetone?? I had a old Japan made Leica screw mount 135mm lens that came in a box of stuff, the helical focus was absolutely " grease welded" I ended up throwing it in the trash. I tried everything. I think it would have required heating it to incandescent temperatures!

 

[OAPOli]

You can maybe find a hole saw of the right dimensions and grind two tabs. Those are hardened steel and would do the job.

I'm not sure what you mean by soaking in acetone, but watch out if this gets to the doublet. Acetone can dissolve lens cement.

 

[r_a_feldman]

You can maybe find a hole saw of the right dimensions and grind two tabs. Those are hardened steel and would do the job.

I'm not sure what you mean by soaking in acetone, but watch out if this gets to the doublet. Acetone can dissolve lens cement.

Thanks for the warning about the doublet.

I would need a hole saw with a 48mm OD, which is 3.5mm larger than 1.75 inches, so a hole saw is out. I usually use old hack saw blades cut and ground to the diameter of the ring if I need to fabricate a spanner. A hole saw will come in play though, in that I will use a 1.75" one to cut a 3/4" oak disk to mount the piece of hack saw blade (set in a slot across the disc). That is a project for tomorrow.

 

[OAPOli]

There are 1-7/8" ~ 48mm hole saws. A cylindrical tool will give you maximum rigidity.

 

[r_a_feldman]

This is what I made, using an old hacksaw blade, 3/4" oak, and a 3/8" bolt, epoxied together. No luck so far, using either a ViceGrip on the bolt or chucked into an electric drill, which gives an impact then stalls.

I will keep soaking the ring in acetone for a few more days...

 

[OAPOli]

Maybe you can show a photo of the ring? I'm not picturing the conundrum.

 

[mshchem]

Is it reverse thread???