Komura 135/2.8 what did I just buy?

[jpb16]

I just got back from a garage sale here in Seattle. I bought a Komura lens 135/2.8 screw mount for $10. But there a several catches.
First one, I knew about: the focus ring is stuck. any suggestions on how to unstick it? I'm thinking some sort of solvent like lighter fluid but I don't want to use the wrong thing.

Second one: I measure the lens with a ruler that was sitting at the garage sale and thought it was M39. Turns out it is probably M42. The other lens markings are Sankyo Kohki. I've seen mention of M42 to M39 adapters but are they real? I'm ok with losing the rangefinder coupling but don't know about the focal plane distance.

And the third thing is the f-stop ring. Why would there be two aperture rings right next to each other? One is smooth and the other clicks. The one that clicks is not directly coupled to the aperture.

thanks in advance. If I'm totally missing some existing threads that answer these topics, let me know and I'll look harder (I already did some Komura searches but wasn't getting the info I was looking) I know the picture is crappy but some folks live by seeing a picture before they comment. (oops, no offense).

 

[Larry H-L]

It sounds like a "pre-set" lens for an M42 SLR. I have a 135 Komura in LTM, but it is an f3.5.

With the two aperture rings, you set one to your chosen f-stop, turn the other ring to open to max aperture for focusing, then turn it back to stop down the lens for shooting at the given aperture.

 

[jpb16]

not sure I understand what "pre-set" lens means.

I'm also thinking I cannot adapt a 42 mm thread mount lens into a smaller M39 body unless there is a focal plane distance that allow it.

 

[Roger Hicks]

There is enough extra distance to the focal plane, and yes, adaptors work, but scale-focusing a 135mm lens is hard work. This is why Leica sold (and later built in) rangefinders.

Cheers,

R.

 

[ferider]

You can get the 135/2.8 Komura coupled in LTM for not much money, mine cost around US 60.

Your M42 version is preset, in that the second ring functions as a stop for min. aperture set with the first ring. Good lens.

Roland.

 

[johannielscom]

Lighter fluid on the aperture ring or focus ring probably won't do any good, chances are the obtrusion is mechanical, i.e. something got dislodged. Don't force it, something might break if you do.

With sticky grease, I usually try warmth first. Keep the lens in your living, close to the heating, never let it get warmer than comfortable to handle. See if that helps. If it doesn't the lighter fluid will have a less tough job, should you try that.

 

[jpb16]

thanks for the info. I put a few drops of lighter fluid on it. I assume it is typical for the focus ring to get stuck at end of travel (i.e. at infinity). I'm going to let that soak in overnight and see if I can get the proper screwdrivers to borrow from work tomorrow for disassembly. Being a born cheapskate, I am temped to program the CNC lathe and make up a batch of adapter rings and have them black anodized.

 

[radi(c)al_cam]

(...) Being a born cheapskate, I am temped to program the CNC lathe and make up a batch of adapter rings and have them black anodized.

A lot of people here in this forum would like to have such an adapter -- that could become an entrepreneurial initiative 🙂

Myself being all thumbs, I regard you with envy ;-)

 

[jpb16]

Heat worked. I put the lens in the oven on warm for 3 minutes. I could then work the focus ring back and forth. I unscrewed it enough so I could dribble in some lighter fluid. Now seems to work smoothly. My plan is to buy an adapter ring to use manual focus on my Nikon to see how I like it. Then maybe transition into using it on the Leica IIIf. thanks for all the help.