yukosteel wrote:
I heard from one friend that Lux 35/1.4 intentionally has F1.4 aperture stop not at the very end of ring rotation, to address potential metal temperature expansion.
I've used three Summilux 35s and they all got funky somewhere around the f/1.4 position on the ring. By funky, I also mean the aperture. I think Leica at some point made a decision about something.
Gary Clennan wrote:
Plastic components is also the source of the issue with the focus wobble in ZM lenses.
This is not true. No ZM lens I've opened has them. I'm not sure about the ZM 35/1.4 though.
The larger ZF Zeiss lenses do have it, at least I've seen white teflon rollers in the Makro-Planar 100/2 ZF and Distagon 35/2 ZF.
Even @yukosteel has disassembled some ZM lenses where non can be found. The wobble and focus binding can have other sources too. The Zeiss ZF build is not as robust imho as the recent Voigtlander lenses.
hmzimelka wrote:
This is not true. No ZM lens I've opened has them. I'm not sure about the ZM 35/1.4 though.
The larger ZF Zeiss lenses do have it, at least I've seen white teflon rollers in the Makro-Planar 100/2 ZF and Distagon 35/2 ZF.
Even @yukosteel@ has disassembled some ZM lenses where non can be found. The wobble and focus binding can have other sources too. The Zeiss ZF build is not as robust imho as the recent Voigtlander lenses.
I'm sorry but you are completely incorrect. The Teflon rollers found in some ZM lenses is the primary (not only) source of the wobble issues. Take the ZM28 for example. It has 3-4 variants, the most recent having the Teflon rollers replaced with brass material. Perhaps you have been lucky and had more recent build versions. Either way, it's a crummy design and unfortunately they won't sell replacement rollers anymore.
Gary Clennan wrote:
I'm sorry but you are completely incorrect. The Teflon rollers found in some ZM lenses is the primary (not only) source of the wobble issues. Take the ZM28 for example. It has 3-4 variants, the most recent having the Teflon rollers replaced with brass material. Perhaps you have been lucky and had more recent build versions. Either way, it's a crummy design and unfortunately they won't sell replacement rollers anymore.
OK, I'm curious where in the assembly does one find the teflon rollers in the ZM 28/2.8?
I certainly don't see where there is space for cams and rollers in the designs of the simpler Zeiss ZM lenses so if you have some info on this it will be appreciated. Certainly then what parts once were teflon that are now brass?
The ZM Planar 50/2 has also been known to wobble and bind with focusing. There is no part in that lens that could have been substituted with teflon rollers. Same for the Biogon-C 35/2.8. The retaining ring that holds the optical block into place can easily work itself loose slightly and cause optical block wobbles when changing focus direction. Zeiss started using thread lock for these parts, which makes opening these lenses rather difficult at times.
The ZM 28 is not much different to the Biogon-C 35, Planar 50/2, C-Sonnar 50, etc... perhaps @yukosteel@ has some info relating to his experience with this.
hmzimelka wrote:
OK, I'm curious where in the assembly does one find the teflon rollers in the ZM 28/2.8?
I certainly don't see where there is space for cams and rollers in the designs of the simpler Zeiss ZM lenses so if you have some info on this it will be appreciated. Certainly then what parts once were teflon that are now brass?
The ZM Planar 50/2 has also been known to wobble and bind with focusing. There is no part in that lens that could have been substituted with teflon rollers. Same for the Biogon-C 35/2.8. The retaining ring that holds the optical block into place can easily work itself loose slightly and cause optical block wobbles when changing focus direction. Zeiss started using thread lock for these parts, which makes opening these lenses rather difficult at times.
The ZM 28 is not much different to the Biogon-C 35, Planar 50/2, C-Sonnar 50, etc... perhaps @yukosteel@@ has some info relating to his experience with this....Show more →
You don't know where the rollers are located but you've disassembled a few of them? I will see if I can find a few pics for you but this was a year ago so they are likely gone. Trust me, there are Teflon rollers in earlier builds of the ZM28. All the best.
Thanks for extra details regarding ZM build. I personally had very less than a dozen cases of servicing ZM lenses, and most cases required only focus calibration or aperture chamber cleaning.
Based on what can be seen in CV 35/1.4 II where brass rollers are used as helicoid guiders, I'd imagine that Cosina involving similar design in their ZM 28/2.8 due to similar packed compact size of focusing mechanics. It's quite possible that teflon rollers were used in earlier models of CV lenses too. Definitely putting rollers instead of straight brass bar as a helicoid guider is making focusing even more smooth and easy.
The ZM 35/2 I opened most recently has regular brass helicoid bars, though that lens is larger and doesn't require minimizing of moving mechanics to standards of much more compact lenses.
Back to the point that spare brass rollers can't be ordered - fortunately it's very friendly material for a relatively simple DIY project if you have high speed rotary tool. I'd cut piece from brass rod, drill central hole and attach it to rotary tool, then use sandpaper to precisely shape it to original roller diameter.
