DIY repair for 40 1.4

[presspass]

I've had this lens a while and enjoy the way it works in black and white. It has two issues, however. The rear retaining ring around the lens element group comes unscrewed. I tighten it, but that only works for a while. Is there a DIY fix for this? The second issue is a persistent squeak when I focus the lens. Again, is there a DIY fix? Thanks

 

[dyavrom]

i had a similar issue with my 35 1.4 nokton. the squeaking is likely not enough grease on the focus threads. i just unscrewed the mount, pulled apart the lens and placed some bicycle grease. the element group that comes unscrewed could be a faulty screw that locktite should would just fine to hold. but do be careful, i remember i had a terrible time putting everything back together because I didnt bother aligning the screw mounts properly. id recommend taking photos each step of the way so you have something to refer back to.

 

[weather]

I have the same squeaking issue with this lens. I also surmise that the cause is a dry focusing helicoid. not sure that bicycle grease is the most permanent solution, perhaps a wax based lubricant. But I haven't disassembled the thing yet.
If either of you have a diagram for this lens I'd be really appreciative.

 

[weather]

Alright so last night I repaired my Nokton 40mm 1.4...it was a stressful experience.

Symptom: Squeaky when focusing

First I scribed the lens mount to the depth of field ring and then proceeded with the removal of the mount by the 4 screws on the back.

In retrospect it would have been intelligent to take note of the following:
-position of the lens (position of the focus ring)
-position of the mount after unscrewing it from the helix
-position of the inner helix

Following removal of the mount the helix was exposed and I noticed no sign of lubrication. I applied a small amount of thick wheel bearing grease using a tooth pick.

This is where it got stressful. It is quite difficult to screw the mount back on, also it is important to start threading the mount on by the exact same thread it came off or else the lens wont focus properly. I screwed (har har) around with this for the better part of an hour each time with the lens ending up in an incorrect position. One time I threaded the mount back on and the lens focused properly! But then I realized that the mount was on upside down...

****...I just wrecked a $400 lens

But after I gave it a break and came back to it with a fresh mind I was able to wind the inner helix all the way in, independent of the focusing ring and synchronize that with infinite focus position, essentially 'resetting' the lens position. Once here I counted the threads on the mount and realized how many different positions this thing could screw on so from here is was trial and error to get the little screws on the mount lined up correctly.

It took a few tries but eventually it worked. The lubrication to the threads effectively stopped the squeaking. It feels like new!