Disassembly - Voigtlander 35mm F1.4 Nokton Classic II S.C Leica M mount lens

 This article shows how to disassembly focusing mechanics and front nameplate area of Voigtlander 35mm F1.4 II Nokton Classic S.C lens in Leica M mount. It may be also useful if you need to calibrate rangefinder focus precision. 



It is second generation of Voigtlander 35mm F1.4 Classic lens with updated optical formula to reduce focus shift - optical shift of focus location when closing aperture. Though I'd assume that mechanically it may be similar to version I . One noticeable difference externally is aperture ring with straight but more durable and thicker control leaves.

I'm usually protecting front glass with custom modified shaved version of B+W IR cut filter. Without filter lens look quite familiar and Single Coating has yellow tint.


Front disassembly

Initially I had assumption that front nameplate should be unscrewed CCW following filter thread (like in Zeiss ZM lens). But Voigtlander 35mm F1.4 II has front nameplate attached with glue. I'm using acetone accurately radially applied around outer nameplate edge while lens facing up and let it stay for few minutes to soften the glue.


After that I'm using strong double-sided adhesive foam pieces connected to nameplate areas while avoiding putting adhesive on top of letterings to not damage white paint. Then I'm attaching on top 37-39mm step up ring and taking nameplate out.


As I mentioned in previous articles, Cosina factory often applies glue to almost every bolt of recently produce Voigtlander lens. This Voigtlander 35mm F1.4 II is no exception.

Here's one way how to safely break the glue without the risk of stripping bolt head. You can add a tiny drop of acetone to bolt head first to soften the glue around bolt head. Then use precision JIS screwdriver with rotation disc at handle end to firmly press on it with thumb finger while pressing on lens with palm edge to hold it firm. Hold pliers in other hand and grab screwdriver, then rapidly move pliers to rotate screwdriver CCW by about 5-10 degrees. You will hear noticeable "click" of breaking glue, though few next screwdriver turns need to be still performed using pliers assist but make sure that bolt head is also rotating.

Picture below shows approximate position of screwdriver and pliers, I'm holding them with one hand while taking picture with other hand.


After unscrewing three bolts and removing hood mount ring there is nothing to further disassemble. Looks like aperture ring can be removed from opposite side. Though at this point you can check if there is no dust and replace grease. Access to unscrew front optical module is also easier at this point.


 I'm assembling front area back. Instead of glue I'm using thin adhesive to connect front nameplate.



Rear area and focus mechanics disassembly

Space to access retention ring is quite tight. First lens need to be focused to closest distance.


You may use spanner wrench to catch two sockets on retention ring to unscrew it CCW, though it is quite thin and can be easily damaged. I'm following another approach. It requires plastic cylinder of same diameter, so I'm cutting it from pills container, then adding adhesive putty on edges.


Pressing firm at retention ring edges it can be unscrewed CCW.


Then I'm disconnecting optical core from focusing frame.

In case you need to access aperture clicks area check image below. Green arrows show aperture transmission that need to be took out first, then brass retention ring need to be removed to release aperture ring. I'm skipping that steps since aperture clicks work perfect.


There is set of calibrating shims, to remove it following pin need to be removed.



If there is dust migrated to aperture chamber whole rear optical frame can be unscrewed CCW. I'd recommend to use rubber strap wrapped around optical frame instead of spanner wrench because edges are quite thin.

Green arrow shows sockets to fit pin of optical core when assembling lens back, and brass rollers should fit two side sockets on optical core frame.


Focusing frame is crafted with very high precision and made of durable brass and aluminum rings.

Looks like focusing rotation has some extra movement similar to Voigtlander 40mm F1.4 lens, so I'm planning to extend minimal close focus range to 0.65m and share details in next article.

One of brass helicoid slider is intentionally split for easy correction of transmission precision. Everything is optimized for very smooth helicoid moves while using single focusing knob.



Unscrewing four bolts allowing to remove ring with distance scale.

  


Flip the lens and unscrew four mount ring bolts.


Accurately pull the mount ring up without rotating it, then flip it and put on the side.


Next step is to remove DOF scale ring. 


If you decide to unscrew and clean rangefinder couple helicoid thread, slowly unscrew it and memorize disconnection point because it has multiple thread connections.

Now I'm assembling lens back.



Conclusions

Cleaning and repairing Voigtlander 35mm F1.4 II Nokton Classic requires lots of attention due to compactly packed mechanics. There is strong securing glue applied to every bolt which increasing risk of stripping bolt head or damaging screwdriver. Definitely this disassembly is not recommended to perform unless you have lots of experience. From the other side mechanics is beautifully made and designed to last for decades if properly maintained. Reaching aperture chamber for dust cleaning is relatively easy if you have proper tools and lens has simple way to calibrate rangefinder focus precision.

Voigtlander 35mm F1.4 remains one of my favorite lens and it performs excellent optically and mechanically on M camera and also adapted on Fuji X, delivering classic image rendering with unique character. Now when I learned more about how to clean and maintain it, this lens has even higher long term practical use value.


Disassembly of aperture ring area

Later I also disassembled another Voigtlander 35mm F1.4 II Nokton Classic MC to repair aperture ring. 


Extending MFD to 0.62m

Following article is showing lens modification steps to allow wider focusing ring rotation range to reach minimal distance of 0.62m comparing to factory default 0.7m




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