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Leitz 40mm f/2 repair clean and lube

leica m rangefinder repair clean lube

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#1 Erik Lund

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Posted 05 October 2012 - 20:43

My Trusty little Leitz 40mm f/2 was suffering from aging grease, Canada Balsam and the internal black paint had begun to become detached also so a repair was needed. I also wanted to add a modern focus tap. Since the lens is so cheap I decided to try it out myself.

I have a lot of knowledge about AF and MF Nikkor, Cannon Olympus and Voigtlanders SLR and Leica mount lenses, most parts of the design and build is same same :-) but this tiny Leica has some differences as to how it's put together. First I was very disappointed to find that the front threads part series 5.5 threads is glued to the aperture housing, next I found that the rings that 'normally' have two holes or ridges for lens spanners for tightening the old Leitz lens had one or even none, so had to be taken apart with friction, a rubber tube of the right thickness must be used to reach into some parts of the lens to get it apart, I modified these rings, drilling two holes makes the hole deal a lot easier.

Got it all dismantled and sorted out, the two elements with the Canada Balsam issue got a 'cooking' treatment in boiling water to separate the two halves.

A drop of Araldite Krystal and the two are inseparable, a coat of mat black paint to finish the job off.
Putting everything back together without leaving dust or prints is the worst part... The old gease was cleaned off and the many threaded focus threads lubed with new grease and put back together as marked by disassembly. The new focus tap needed a slight trim to clear the mounting ring and two extra location holes to keep it in alignment a single screw holds it in place. Everything fits within very tight tolerances; position of glass elements, focus threads so it was a joy to work on it.

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All the parts, note extra holes, the two glass element front center

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Extra holes for focus tap in focus mount.

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Focus mount with focus tap.

24 hours wait for the Epoxy to cure and testing today went very well, focus at infinity and all the way to 0.7m is spot on.
Lens is now in good service condition and much closer to my heart Posted Image

Edited by Dallas, 09 October 2012 - 15:00 .
spit & polish

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#2 Fons Baerken

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Posted 06 October 2012 - 06:43

interesting thanks,
how do you keep dustfree?

#3 Erik Lund

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Posted 06 October 2012 - 10:10

Thanks!

I use wet lens cleaning cloths, finishing off with microfiber lens cloth and a blower with a filter.

I don't mind a few small specs of dust...

#4 Hugh_3170

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Posted 06 October 2012 - 11:22

Hi Erik, congratulations on your successful repair of yet another lens type.

A couple of questions please if I may:

1. Is the use of Araldite Krystal a common replacement for Canada Balsam these days? I am aware that microscopists do use this product for the preparation of archival microscope slides for long term usage, but I have not encountered its use in the gluing of lens elements.

2. How did you keep the two lens elements centred? Did you make up a jig or were their edges pre-ground in some way by Leitz to make them self aligning? Araldite starts to bond in just a few minutes and time is against one, so centering would need to be very quickly established.

Thanks in advance.
Hugh

#5 Tejpor

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Posted 06 October 2012 - 11:30

Erik, hats off... Your dedication is remarkable!

#6 Erik Lund

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Posted 06 October 2012 - 16:45

Thanks!

Canada Balsam has a very very faint brown tone, the Araldite Krystal is completely clear...
No obvious difference in real world images...

Canada Balsam is no longer used. I found that the most common Glue at factories are now an UV cured Epoxy, simply expose the glued elements, when centered, to UV and it hardens, very neat indeed.

Re-cementing the two elements is definitely not easy with Epoxy since it sets so fast, a drop of glue, without air bobbles, is placed at the center then you press the two elements together quickly.
My worst worry was too little glue, not filled to the rim or to much and it would flow out and make it to the surface of the elements...
I was lucky I guess worked nicely...
I kept them centered by feel and a small screwdriver, cleaning fingers - centering, cleaning fingers - centering, cleaning fingers - centering until I was satisfied...

In total you have 5 minutes before the glue sets from you start mixing the two components.
I removed the excess glue with a scalpel. it is very important to apply new mat black paint to avoid reflections and flare.

#7 Hugh_3170

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Posted 06 October 2012 - 16:57

Thanks mate for your answers to my questions - I am now even more impressed!

#8 bjornthun

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Posted 06 October 2012 - 16:58

Erik, I'm utterly impressed.

Cementing and centering two lens elements with glue that sets in five minutes.. :good: :good: :good:
Bjørn T

#9 Alaun

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Posted 08 October 2012 - 16:30

....and put back together as marked by disassembly....

I think, this should be put in bold and larger letters! (I had the fun to put a Noflexar 35mm back together, I had put apart for cleaning, was my first try on a lens)

#10 Erik Lund

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Posted 08 October 2012 - 17:08

I agree, and at the beginning :) On the other hand you learn a lot from your mistakes...

Edited by Erik Lund, 08 October 2012 - 17:08 .


#11 Akira

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Posted 09 October 2012 - 11:39

Erik, you re-glued the elements? That's awesome!
"The eye is blind if the mind is absent." - Confucius

http://www.flickr.co...tos/akiraphoto/

#12 stenrasmussen

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Posted 09 October 2012 - 12:26

Another proof...Erik IS the Dr. Lens :yes:
Machina fotografica necesse est

#13 Erik Lund

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Posted 09 October 2012 - 12:45

Thanks!

Yes Akira, the lens had to have the old Canada Balsam (glue) replaced...





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