Leica Summilux-M 35mm F1.4 Steel Rim reissue 11301 lens has minimal focus distance (MFD) of 3ft or about 0.9m. In this article I'm discovering and then performing experimental modification of lens focusing mechanics to increase closer focusing range to about 0.76m . This modification requires precise and accurate grinding of five separate parts, a lot of attention and patience.
Closer focus range estimation
I'm working with Leica Summilux-M 35mm F1.4 Steel Rim reissue lens copy generously provided for experiment by Fred Miranda after few theoretical discussions regarding possibility of extending closer focusing range. We came to conclusion that closer look and partial disassembly is required first, then decide on possible next steps. You can check details in Leica 35mm F1.4 Steel Rim reissue lens disassembly article.
During disassembly I discovered significant difference of focusing mechanics comparing to older versions of 35mm F1.4 Steel Rim lens. It became obvious that metal grinding is required to accurately extend range of movements. The core idea of mod is quite similar to what I was doing before with Voigtlander 35mm F1.4 II Nokton Classic lens to extend closer focusing to 0.62m .
Though with Voigtlander it only required grinding of one metal bar limiting MFD, but in case of Leica 35mm F1.4 Steel Rim reissue lens there are five locations that require grinding:
- MFD focus stopping bar of outer RF helicoid ring
- elevated area of inner RF helicoid ring
- side wall of RF helicoid guider
- side wall of RF helicoid guider mount on focus ring
- MFD stopping point on focus ring outer edge
Fred decided that adding 10cm to close focusing range is quite useful and is well justifying to give it a try, so I proceeded with next steps.
Closer focus modification steps
I'm opening lens again and would like to point your attention at first part requires grinding - it's outer RF couple helicoid ring that is also holding focusing helicoid guiders and have radial elevated area to limit focus ring rotation.
To avoid extra steps on cleaning and replacing factory applied grease I'm covering part with paint masking tape. Then using precise file slowly and accurately grinding out part of that bar limiter. It does not need to be cut completely to the base, but it is quite important to keep the new edge square.
Next area where this bar meets with focusing ring RF helicoid pin need to be grinded.
I'm using masking tape again.
I've grinded inner radial area and then realized that helicoid pin need to be temporarily disconnected. It is important to memorize it's exact position when mounting back since it is affecting precision of RF cylinder position. After removing guider I've also grinded right side of it's mounting base.
Then I mounted RF helicoid guider back and performed another grinding cut on top area.
At this point focusing ring can move further once connected, though the silver pin of infinity focus lock is hitting edge on the focus ring at 9ft distance, so that area on focus ring needs to be masked first and then grinded up to middle of infinity mark.
After this grinding and cleaning I'm assembling focus ring back.
Grinding of that four areas was a relatively simple though time consuming process. All these areas remain inside and not visible once lens is assembled, so there is no need of fine polishing, painting or oxidizing cut surfaces.
At this point modified Leica 35mm F1.4 Steel Rim reissue lens can be assembled together and it is focusing smooth down to about 0.76m according to what I see when mounting on Leica M10P camera and checking Live View focus and measuring distance to focused object using ruler.
Modification is complete if you only need this lens to focus closer while using Live View or adapting it on another mirrorless system camera. Though for that second scenario it's much easier to just purchase close focus LeicaM-to-other-system adapter. Though if you need this Leica Steel Rim reissue to work with Leica M rangefinder patch at closer focus - lens requires one more step.
Modifying lens rangefinder couple cylinder
Lens RF couple cylinder have protruding elevation designed as a reserve space for RF helicoid sliding pin.
When modified Leica 34mm F1.4 Steel Rim reissue is mounted on Leica M camera and focusing is passing 3ft, the camera RF roller is moving on top of the elevated area.
That is making Leica viewfinder focusing patch to suddenly move into opposite way and show incorrect focusing distance. To solve that all the elevated area of extended travel for camera RF couple roller need to be grinded. The challenge is that RF couple cylinder is not perfectly flat - it's wall height is gradually decreasing in a CCW direction, so grinding should follow that path.
I have to say that it was most time consuming part of this mod, it took me about 2 hours of manual grinding and polishing of that small area.
First I'm applying masking tape and adding tape layer to the opposite side of cylinder. It is important to use small flat metal file and keep it parallel to the cylinder edge surface in the grinding area and also in the opposite area.
While grinding I was taking a break very often and looking at grinded area from very low angle to check if the "path is smooth" by observing the transition area starting much before the grinding point. It's hard to find proper words to explain precisely, but it's like working with curves in vector editor - observed curve of path should look smooth without bumps. I was very carefully and slowly removing material by gentle grinding mixed with polishing here and there until "the road" started to look like below.
Final step was to use acid to darken the metal, and then accurately assemble lens back.
If you look at RF couple connecting area the light gray surface color shows where grinding and polishing is done.
Now Leica RF couple roller is moving very smooth while passing to much closer focus position on lens RF couple cylinder edge. Focusing patch in viewfinder is also moving smooth indicating closer focus due to lens RF couple cylinder keeps retracting into the lens during focusing. The precision error depends on how even and smooth is the curve of RF couple cylinder, though it's very minimal.
Conclusions
It's great to see that Leica Summilux-M 35mm F1.4 Steel Rim reissue 11301 lens is constructed with a bit of extra capacity for closer focusing. It could be easily the case that RF and focus helicoid pins meet each other at 3ft distance which would make closer focus modification impossible. Though now it's discovered that lens is capable of well functional and smooth focusing down to about 0.76m MFD.
These results wouldn't not be possible without great support and dedication of Fred Miranda who initiated this discovery, provided his own lens, and most important decided to move forward with lens modification, thank you Fred!
It was interesting and challenging journey, though with what is explored now and proper skills and time it is possible to repeat this modification on any other Leica Steel Rim reissue lens. It's definitely not a random DIY project you'd decide to run over weekend - some level of precise machining or manual grinding skills are required. It's rather a guiding line to share with your local lens repair expert and ask if they'd be able to perform this mod.
Picture samples
Looks like there is no significant IQ degradation at 0.76m focus distance. Check how modified lens optically performs comparing to default MFD by looking at test pictures set taken by Fred Miranda.
Being able to move camera much closer to target you have wider range of perspective control. Even though that extra 0.14m distance sounds negligible, but change to perspective is significant. I think that many skillful photographers could find that extra flexibility quite useful and practical enough to prefer extended MFD comparing to default one. Leica M system rangefinder is still very precise at this distance and it's very easy to nail focus quick regardless of minor parallax.
Extra disassembly pictures
I've made more pictures during disassembly so putting them here in case you need to take a closer look at some parts from other angles.
I wonder why leica didn't just do this standard
ReplyDeletePerhaps their goal was to reissue ability to take similar range of pictures and closer focusing didn't fall into that requirements, which could also lead to extra work/cost.
Delete