CLA Disassembly - Voigtlander 50mm F2 Heliar lens in Leica M mount - collapsible 250th Voigtlander Anniversary version

 Cosina commemorated Voigtlander 250th anniversary by producing very unique and limited set of Bessa R3M / R2M rangefinder cameras paired with Voigtlander 50mm F2 Heliar collapsible lenses in Leica M mount. There are only 1700 black and 800 chrome versions produced according to info from CameraQuest. I've recently acquired one copy that needed CLA and discovered the disassembly process which is now share in this article.






Rare and unique Voigtlander 50mm F2 Heliar collapsible

It's quite hard to find Voigtlander 50mm F2 Heliar lens for a reasonable price. Usually it's being sold together with Bessa R3M or R2M camera and the price keeps slowly elevating over years due to the rarity. I purchased first copy about 10 years back for a bargain price of about $450, that lens required minor dust cleaning from the aperture chamber (which I did successfully) but also had some wobbling of focus and mechanics (that I had no skills to investigate and repair at that time). It was a great lens to shoot with 50mm F2 Heliar adapted on Fuji X cameras, with the minor downside of minimal focus distance is only 1m. At some point I sold the lens when shifting my attention (and budget) to another Voigltander lenses, but after that was missing it's unique rendering and mechanical design.




The lens is collapsing to a more compact size when not in use. When lens is retracted it is still focusing and interacting with camera rangefinder, you need to pull front area out and rotate CW to lock it in extracted position. It should be a strongly built habit, otherwise it's easy to forget and take completely blurry pictures on Leica M camera.




Recently I was able to find another used copy of Voigtlander 50mm F2 Heliar in almost perfect working conditions, though with minor mechanical issues. This time I have some extended experience with performing CLA and exploring previously unknown internals of Voigtlanded lenses, so it was easier to safely explore proper steps.




Voigtlander 50mm F2 Heliar - disassembly steps


I'm adding few terms and labels to photos of separately placed set of Heliar 50mm F2 parts below to refer them later in further CLA steps.






Front optical area disassembly

One of common Voigtlander 50mm F2 Heliar issue - is the fungus or dust in the aperture chamber. The disassembly steps to access that area from the front are relatively simple. The only challenging part is the factory glue applied to parts and bolts, so you'll need to use acetone or heating bolts with soldering iron.

Steps:

  1. Apply drop of acetone to the front filter thread and let it soak factory glue
  2. Use hollow rubber cylinder to unscrew the front black nameplate in CCW direction
  3. Apply drop of acetone then unscrew three black bolts holding the chrome hood mount ring, remove the ring
  4. Apply drop of acetone to the outer edge of front glass frame, wait for a minute, then use hollow rubber cylinder to unscrew front optical module in CCW direction. NOTE: module frame has two sockets for spanner wrench - do not use them, there is high risk for wrench to jump out and scratch the ring or glass, using hollow rubber cylinder is safer and keeps the metal surface coating intact.
  5. Open aperture to F2, and use air blower to remove dust from glass surface in aperture chamber. NOTE: do not place front optical module on table - it has flat protruding glass surface on both sides, place it on a hollow cylinder or clean paper towel.

Focusing mechanics maintenance





Due to collapsible mechanical design some disassembly steps are easier to perform when lens is retracted. First you need to disconnect lens optical core from the focusing frame.



Detaching optical core form focusing frame


Steps:
  1. Collapse the lens core, then apply few drops of acetone between the outer edge of black ring "5" and "3b".
  2. Use hollow rubber cylinder to unscrew cylinder "5" in CCW direction.
  3. Accurately pull out optical frame "6" from the focusing frame. NOTE: there is a set of brass shims for infinity focus calibration. The "3b" cylinder has the small removable metal pin on the inner wall matching the rectangular socket on "6" frame. Infinity calibration shims may catch the pin when extracting, so point extra attention there.
At this point optical core and focusing frame are separated, which is opening access to disassembling and maintenance of focusing and collapsing mechanics.


Opening focusing frame - rear area


Steps:

  1. Unscrew four bolts on the lens mount ring and detach mount ring.
  2. If you need to calibrate rangefinder precision, next steps is to apply drop of acetone between outer edge of "RF ring" and brass thread. Let it soak for a bit, then grab focus ring "2b" with one hand and use hollow rubber cylinder to unscrew CCW the black "RF ring". There is set of thin shims under that ring, calibrating its elevation.
  3. Apply few drops of acetone, then unscrew three small black bolts positioned in a row on the mount side of focusing frame "2a". NOTE: in my lens copy there was large amount of factory glue on all three bolts and I had to use soldering iron on low temperature to melt the glue before unscrewing bolts. Though one bolt was dead stuck and I had to drill the head a bit to use torx bit and finally unscrew it (later replaced by similar bolt). It's also important to use JIS screwdrivers and apply initial rotation torque using pliers to break the glue.
  4. Slowly rotate fame part "2a" in CCW direction and mark helicoid thread detaching point. In my current Voigtlander 50mm F2 Heliar copy rings are detaching when 1.5m focus scale line on "2b" ring is exactly in between last two digits of serial number on "2a" ring.
At this point you can clean the old grease and re-lubricate helicoid thread and thick brass helicoid guider "2c" edges.


Opening focusing frame - front area


Steps:

  1. Apply drop of acetone to each of four black bolts on front plate "4c", then accurately unscrew them.
  2. Use sticky edged cylinder (I'm using strong double-sided adhesive tape on plastic cylinder) to extract black plate "4c".
  3. Take out brass compression ring "4b".
  4. Take out thick brass shim plate "4a" (it's 0.3mm thick)
  5. Accurately extract the collapsing frame "3a" - looks like it is the most heavy part of focusing frame designed to hold extracted lens firm and precisely when locked.
  6. In case the switch focus direction is showing some lag, shift the position of "3c" brass L-plate to make tighter fit of helicoid guider "2c". In my Heliar 50 F2 copy this brass L-shaped "3c" part was slightly bent, so I just straightened it using flat pliers. It completely eliminated minor focus ring radial play.
Access to inner focusing/collapsing mechanics is allowing to perform grease cleaning and replacement. The lens copy I have is showing some minor longitudinal play of "3a" frame inside of "2b" ring. I decided to experimentally increase the thickness of shim "4a" by cutting similarly shaped ring with 4 drilled bolt sockets, made from 0.1mm thin aluminum sheet. I placed that extra shim under "3a" during assembly. It resulted by significantly reduced longitudinal play and much more accurate focusing of lens.


Closer MFD modification of 50mm F2 Heliar classic


The Voigtlander 50mm F2 Heliar has radial arc cut in focus ring "2b" providing moving range of helicoid guider "2c". Stock version is allowing lens to focus from 1m to infinity. It feels a bit limiting in some shooting situations comparing to modern Leica M mount Voigtlander lenses that often allowing to focus much closer down to minimal 0.65m supported by optical rangefinder of latest digital Leica M cameras.

It is not possible to allow closer lens focusing without metal grinding and increasing radial arc angle. I performed that type of focus MFD extending on Leica 50mm F2 Summicron rigid lens earlier. It allowed Leica 50mm F2 lens to focus much closer - down to 0.75m.

Cutting "2b" frame is making that part slightly less durable, thought it's made of solid brass, so I decided to perform experimental modification and see how closer lens would be able to focus. I increased arc geometry to 180 degrees angle and reshaped arc cut end to diagonal. The helicoid guider "2c" is now stopping at new extended arc end by pressing with it's angular edge, the downside of that is that helicoid guider socket in inner frame "3a" is only partially holding helicoid guider edge at new MFD, so it requires more gentle focusing back action to not intensify brass part wearing.

Resulting focusing range is measured down to 0.78m which is making modified Voigtlander 50mm F2 Heliar lens more versatile when used on digital Leica M camera. I've spent few day with it outside and focusing closer was very convenient.




Stock focusing range is down to 1m


New focusing range down to 0.78m. The focusing ring "2b" is slightly elevating bottom edge above frame ring "2a".



At this point I'm concluding the CLA Disassembly and going to spend more time shooting with enhanced and fine tuned Voigtlander 50mm F2 Heliar classic lens.




Pictures from Voigtlander 50mm F2 Heliar










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