Adjusting focus & aperture ring Tele Rokkor QD 135mm

perkus · Joined: 13 Mar 2012 Posts: 5 Location: Brussels

Hi everybody,

long-time lurker finally decided to register - as I want to skill up in repair and need some help.

I bought a Minolta MC Tele Rokkor QD 135mm / f3.5 cheap for 3Eur off ebay.

Despite the glass looking excellent and clean, the focus and aperture rings dont work properly. The focus ring only moves between the 2 metre and infinity mark (minimum distance is indicated as 1.5m on the ring). Somewhere before the 2metre mark something clicks/sets off and the aperture ring does not move the blades anymore.

Just to be clear: I have some experience with mf lenses but this is my first time trying to repair a lens, and I chose this one deliberately as it came cheap and I might not miss it too much in case something goes wrong.

I couldnt find any disassembling/repair instructions on the web for this particular lens, hence my questions:

What could be wrong, how could I repair it and what tools would I need?

Thanks in advance for any help.

peterqd · Expire: 2014-01-04

Hi and welcome!

It sounds to me as though the lens has been wrongly reassembled. The focus problem is probably due to the helicoil being threaded wrongly.

This lens sometimes suffers sticky blades, at least mine does. Are the blades stuck open or closed? The protruding lever which links to the camera is a direct connection to the blades, so you should be able to actuate them with this (with the ring set on f16), even if it doesn't move under its own spring tension. If you can't then again it looks like wrong re-assembly.

perkus · Joined: 13 Mar 2012 Posts: 5 Location: Brussels

Hi,

thanks for the quick reply and the welcome.

The blades are stuck open and can be actuated by playing around with the lever, so indeed this might just be sticky blades.

But the wrong adjustment of the focus ring persists, I cant move it "lower" than the 2m mark. I tested it on my gf1 and whilst the focus is definitely moving it seems completely off the specifications on the ring (taking into account the 2x crop of the gf1).

peterqd · Expire: 2014-01-04

I've never dismantled my lens so I can't give detailed instructions right now, but as the blades need cleaning anyway I'm willing to go through it with you if you like. I'll be able to start it on Thursday probably and I'll take some pics as I go.

In the meantime, you might like to gather some tools together. You'll need at least a 1mm or 1.2mm flat blade jeweller's screwdriver, a fine cross head or Phillips screwdriver and a pair of tweezers. A magnet is useful too, and see if you have a freestanding magnifier and a desklamp. Work on a piece of smooth cloth, not fluffy like a towel, and have a few small self-seal poly bags ready to keep parts in.

perkus · Joined: 13 Mar 2012 Posts: 5 Location: Brussels

Hi,

Great - it would be great if you could document how you go through the process and I am happy to follow and document my failure or success Smile

Edit: I managed to assemble the tools you recommended and will try to have a go over the weekenend - any instructions appreciated Smile

perkus · Joined: 13 Mar 2012 Posts: 5 Location: Brussels

Hi, sorry to zombie the thread but I finally had time to do the repair and it was more difficult than expected. In the end both the helicoil was threaded wrongly and the thread of helicoil itself was stuck as it was full of dirt.

I have cleaned it up a bit and it runs more or less ok again, but does anybody have tips on what sort of lubricants I could use to help the helicoil run smoother?

thanks and sorry for reanimating the thread so ruthlessly Smile

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