MC 3M-5CA tight focusing ring fix ?

Flor27 · Joined: 13 Sep 2007 Posts: 1195 Location: Paris, France

Hi all,

I would like to fix the focus ring of my 500mm MC 3M-5CA. It's a bit tight, and I suspect old grease being thick.

Does anyone know how to access to the focus ring helicoid in order clean it and put some fresh silicon grease ?

Thanks

Attila · Expire: 2025-11-18

Nice to see you here ! Thank you for joining us! I have this lens , but works perfect so I have no experience to dissasemble it. I guess it would be not difficult Russian lenses has great construction they are not difficult constructions and they not used glue like some idiot Japananse maker. My suggestio if not makes much trouble to you, just leave it. Dissasemble a lens always risky business I do only if no other way to keep in live.

Flor27 · Joined: 13 Sep 2007 Posts: 1195 Location: Paris, France

Thanks for the warm welcome !

Actually I see two ways to dismantle the lens without touching (I mean not move from the barrels) optical components:

- 3 big screws on the back of the lens (M42 mount side).

- 3 tiny screws on the focus barel, hidden by the fixed barel until you focus closer. This tiny screw were paint at the same time as the focus barrel

This tiny screws seem the maid to remove initially but the fact that they are painted means that they were screwed before the focus barrels was installed.

peterqd · Expire: 2014-01-04

I don't know this lens at all, but I did manage to ease the thick grease problem on one Russian lens (I can't remember which, maybe the Mir-1) by removing the front lens retaining ring, which exposed the front end of the helicoid, and dribbling in a couple of drops of lighter fluid. I loosened the tight ring with a household rubber glove wrapped round the end of a wooden broom handle and then I unscrewed the remainder easily using a pencil eraser.

Attila · Expire: 2025-11-18

To grease a lens helicoid can be dangerous !! if you can put more grease or oil there than neccessary it can be land on blades!!! and you will have nice smooth helicoid and dead aperture. So be carefull do if absolutely neccessary. Aperture assemble not an easy task at all.ANother problem in the factory maker used special grease what would be not be liquid when environment bit worm like summer time in car. Many people had dead aperture blades after "maintenance".

Flor27 · Joined: 13 Sep 2007 Posts: 1195 Location: Paris, France

There is no aperture blade in the MTO lens Cool

Attila · Expire: 2025-11-18

yes right it has fixed aperture Smile

so you have no problem ...

Flor27 · Joined: 13 Sep 2007 Posts: 1195 Location: Paris, France

Good news !

As for now this lens is distributed (and still constructed ?) by Lytkarino Optical Glass Factory, also know as LZOS.

So some days ago I have asked them by e-mail how to re-grease the focus ring. And they have replied !!

Orio · Expire: 2012-12-04

Yes, excellent support.
I wish that many Western Europe, Japan or USA richer companies had the same respect for the customers that LZOS has. They don't have it for registered customers, either -and they make you pay for support- let alone for unregistered customers.

A lesson to learn from Russians, I say.

Attila · Expire: 2025-11-18

As I said in other thread my Nr.1 favourite sellers are Russians! Unbeliavable, they supported an such old lens!

xaprb · Joined: 28 Jan 2021 Posts: 168

An old thread, I know, but it shows up on search engines, so I’ll add something I hope is helpful. Here’s a photo of the lens unscrewed.

The ring on the front part (at right) with the focus distance markings is not part of the barrel, it’s a thin ring that slips over it. There are three set screws that hold it in place. It has a little nub sticking back, which will run into the nub sticking forward in the rear part of the barrel (at left). This limits its rotation to one turn. To take the barrel apart you have to take out the set screws in that thin ring, so the barrel can spin inside it and screw apart all the way. A simple design but perfectly adequate.

Mine unscrewed about 6 and 1/4 turns from the infinity focus mark till the helicoid disengaged. Of course, I put masking tape on the front barrel (on the barrel, not the focus distance ring, which will move…) and marked where it disengaged.

The interior threads in my copy were painted; you can see that in the photo. The old grease was really dried out and hard. I put new grease only on the threads of the front part of the barrel, so I didn’t push a pile of grease into the interior of the lens if I used a little too much. It’s a simple lens to service and now it is pretty easy to focus. If I were to do it again I might try an even lighter grease and see if I could get that Nikon-like focus ease, which would be even better.