Disassembly - Voigtlander 28mm F2 Ultron II Type 1 Vintage Line - Leica M mount lens

 Today I'm attempting to disassembly Voigtlander Ultron II 28mm F2 Vintage Line Type I lens in Leica M mount. I've recently received good questions about this lens from one of blog reader and also DIY lens maintenance person from Namibia (thank you!). Comparing to other compact Voigtlander M mount lenses there are no visible retention rings in mount area, so it was challenging to understand how to open lens properly for cleaning or focusing tuning.

I've purchased this lens few years ago after reading great detailed Voigtlander 28mm F2 Ultron II review performed by Fred Miranda . It performed flawlessly all this time and only reason to open lens today is to support DIY repair questions for cases when shipping lens to service center is not an option. 






Disassembly steps

The key of opening Voigtlander 28mm F2 Ultron is to start disassembly from the front. There is thin retention ring positioned in the filter thread. I'm not using any spanner wrenches to not damage thin detents of the ring. Instead I'm first soaking retention ring borders with few drops of acetone for few minutes. Then I'm cutting plastic pills container to fit diameter of retention ring, attaching thin adhesive Loctite putty to cylinder edges, pushing it against retention ring and unscrewing it.

Note, the front lens glass is protruding above front nameplate, so make sure you use hollow cylinder side for unscrewing retention ring.


Now the front nameplate can be removed. It has three sockets at rear side to be positioned above three bolts holding the front hood mount ring during reverse assembly.

Next step is to unscrew three most deep positioned black bolts marked on picture below.


After unscrewing three bolts lens optical core frame can be disconnected from the focusing frame.

Few front optical elements are framed into separate casings that can be precisely positioned for tuned optical centering. Glass frame holding bolts are secured with factory glue, so it's important not to unscrew that bolts unless you plan to later deal with optical re-centering.


Voigtlander 28mm F2 Ultron lens has set of infinity calibration shim rings marked below.


Optical core frame and inner tube of focusing helicoid have more complex surface with about 45 degree angled radial surface.


Focusing helicoid has two thick brass guiders for focusing, and two sitting deeper - for rangefinder couple cylinder.


Whole rear optical frame consists of two cylinders. Unscrew all two without separating them to access aperture chamber for internal glass cleaning if needed.


Conclusions


I think Cosina did excellent job with mechanical design of Voigtlander 28mm F2. All parts are very durable and precisely tuned, lots of brass used in focusing frame for extra durability. Lens has surprisingly large number of bolts and calibrating parts for such a compact mechanical design, which is making it much better optical performer comparable to Leica 28mm lenses. Once you know steps and have proper skills and tools - it's very easy to open lens and focusing mechanics for maintenance and cleaning. Though it's important to not open areas that may affect optical centering precision.

The way optical core is connected to focusing frame is similar to Voigtlander 50mm F1.2 M mount lens, and requires front nameplate to be removed first unlike most common way of disassembly from mount area. Cosina engineers definitely introduced new level of mechanical quality standards with latest Voigtlander Vintage Line lenses generation. It's a joy to take pictures with these little lenses on M camera and particularly Voigtlander 28mm F2 Ultron II also performs excellent when adapted on Fuji X body.

It's important to add that internal mechanics of Type 1 and Type II versions of this lens model is identical, so disassembly steps are applicable to Type II.






4 Comments

  1. Thank you for continuing to do these disassembly/repair posts. You have created a valuable resource in a not very well documented genre of self repair.

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    Replies
    1. You are very welcome Brandon. In most cases lenses are getting opened due to some practical maintenance question to be solved. Additionally I'm trying to return the favor to large number of DIY repair resources and forum threads that helped me with the past repairs and allowed to train skills for current projects.

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  2. I have a slight issue with my ultron 35mm 1.7 in m-mount (the now discontinued one) where the lens body/upper part has an ever so slight play sideways, the helicoids/focusing mechanism is buttery smooth, so it is likely the attachment screws that need some tweaking. I have yet to find a disassembly of the ultron 35mm 1.7 m-mount version, and I wonder if it might also share a similar construction, if you have any clue.

    It also shares the locking ring for removal of the nameplate, and being a lens that went on sale back in -15 it hopefully shares a similar construction.

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    Replies
    1. Hi Johannes, the Ultron 35mm 1.7 released at similar time as Nokton 50mm 1.5 (first version in M mount), so most likely they have similar build design. I had chance to open Nokton many times, but sold my Ultron 1.7 long time ago and can't check it now. I'll take a closer look at pictures online and provide you with more details.

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