MOD - closer focusing distance of 0.62m - Voigtlander 35mm F1.4 II Nokton Classic S.C

 This article explains modification steps for lens to extend MFD from 0.7m to a bit closer 0.62m. It requires disassembly of focusing frame and accurate grinding of focus ring limiter. If you are sensitive to pictures of drilling or grinding lens internals, it's better to just check final result on first image below and skip further read.

Disassembly steps

Check disassembly article on Voigtlander 35mm F1.4 II lens and follow steps to disconnect optical core and then take apart focusing frame.

Focusing frame modification

Modification idea is similar to performed in article on 0.65m close focus for Voigtlander 40mm F1.4 Nokton Classic 

Frame mechanics allow to rotate internal cylinder in slightly wider range than 0.7m-infinity. Minimal position is closer to 0.6m but there should be some space left for sliding helicoid socket of optical core frame.

You can see on image below that helicoid sliding pin and silver plate holding roller are positioned too close if rotating focus ring past 0.62m. Most safe modification is cutting MFD limiter to allow rotation down to 0.65m position. I'm grinding a bit more though for experimentation.

Image below shows focus ring position rotated to approximately 0.6m, where protruding square pin should pass the blocking horizontal frame bar. I'm marking slightly closer position and need to grind out approximately 7mm of that MFD limiter.

One way is to completely disassemble remaining focusing frame, clean out grease, grind, then clean, add grease and assemble it back. That takes lots of effort, so I'm simply wrapping internal frame into masking tape. About 7mm of that protruding section need to be grinded.

I'm using thick leather piece to safely mount frame into vise. Then slowly (to avoid overheating) and accurately grinding most protruding area of focusing limiter.

Next step is to finish the grinded surface using precise metal file, then bluing aluminum. Once that is done I'm removing masking tape, and all surfaces remains clean and free from metal dust.

Image below show new location of focusing limiting edge which is now about 7-8mm further to the left from original location.

After attaching focus ring I'm checking that protruding pin can move further up to new position of MFD stopper without touching grinded wall of frame.

Finally, I'm assembling focusing frame back, attaching optical core, and checking again that focusing ring is rotating freely in full range. Images below shows full extended focus range.

Measurement from camera to in focus object shows 0.62m distance which allows to focus 8cm closer which is great to have when shooting this lens adapted on Fuji X-Pro3.