Vickko
Veteran
I found an LTM Zunow 5cm f1.1, but the inner surface is marred. It looks like the lens surface right behind the iris has been cleaned, as it looks like someone has taken a sandpaper sheet across the surface. I hope it is only the coating that is damaged, and that I can repair it.
So, does anyone know how to take apart the LTM 5cm Zunow?
I can only see three screws on this lens, at the iris ring. I am guessing and hoping that if I take these screws out, the ring slides back to reveal more screws.
Trying to twist the front lens group off isn't working, either the head doesn't twist off, or it is infinitely tight, or something is holding it.
The final thing is that the front lens retainer (and label ring) might need to come out to disassemble the lens, but I don't know of many lens designs where you have to take the front lenses out individually to get to the rear group. The designs I know, have the front group coming off, as a group.
Anyway, does anyone have experience with the Zunow 5cm LTM?
....Vick
So, does anyone know how to take apart the LTM 5cm Zunow?
I can only see three screws on this lens, at the iris ring. I am guessing and hoping that if I take these screws out, the ring slides back to reveal more screws.
Trying to twist the front lens group off isn't working, either the head doesn't twist off, or it is infinitely tight, or something is holding it.
The final thing is that the front lens retainer (and label ring) might need to come out to disassemble the lens, but I don't know of many lens designs where you have to take the front lenses out individually to get to the rear group. The designs I know, have the front group coming off, as a group.
Anyway, does anyone have experience with the Zunow 5cm LTM?
....Vick
The Zunow 1.1's are exceptionally difficult lenses to take apart. Most experienced techs won't be able to disassemble it.
Stephen
Stephen
rlouzan
Well-known
Hi Vick,
Send it to John Van Stelton.
Regards,
RLouzan
Send it to John Van Stelton.
Regards,
RLouzan
johannielscom
Snorting silver salts
What Robert says,
John van Stelten at focalpoint is the man to get the job done.
Or, you can just donate it to me
John van Stelten at focalpoint is the man to get the job done.
Or, you can just donate it to me
Vickko
Veteran
Hmmm, thanks Stephen. Do your tech's work on the Zunow? I love a good challenge. I'm travelling now, so the Zunow may become my "June/July" project.
Vick
Vick
Vickko
Veteran
Update. After a discussion with John van Stelton, I'm likely not going to try this myself. e.g. from Clint Eastwood "A man's got to know his limits".
He did talk me through the disassembly - pretty scary in itself but not insurmountable. But he did tell me what I'm likely dealing with on that one inner surface, as he's done lots of them. Seems typical of Zunow 5cm lenses. No way to easily clean it off. He's done the successfully, but it is an enormous job.
So, I'll test mine some more and see if the surface affects imaging.
...Vick
He did talk me through the disassembly - pretty scary in itself but not insurmountable. But he did tell me what I'm likely dealing with on that one inner surface, as he's done lots of them. Seems typical of Zunow 5cm lenses. No way to easily clean it off. He's done the successfully, but it is an enormous job.
So, I'll test mine some more and see if the surface affects imaging.
...Vick
johannielscom
Snorting silver salts
Let's hope it's stil usable, I'd love to see some shots from and with that lens, Vick!
Happy shooting!
Happy shooting!
rlouzan
Well-known
Vick,
What did he say is the cause of this problem?
Regards,
RLouzan
What did he say is the cause of this problem?
Regards,
RLouzan
Vickko
Veteran
John says typically moisture, that gets on the surface, and the degradation just etches into the glass.
I just got a roll back and the images look fine. Not super critical testing, but on a bright sunny day, images are good, sharp, contrasty. Smallest diameter I went to was f8.
I'll need to do some fully open shots.
...Vick
I just got a roll back and the images look fine. Not super critical testing, but on a bright sunny day, images are good, sharp, contrasty. Smallest diameter I went to was f8.
I'll need to do some fully open shots.
...Vick
Nick Cecchini
Newbie
I know it's a longshot but do you have any memory on being talked through the disassembly of this piece? Any notes or anything? One has come across my shop but my technician did it about a decade ago and is having trouble remembering how to get into it. Thanks
Zunow lenses are extremely difficult even for the experienced tech.
Unless you are willing to buy it, best leave it alone.
raydm6
Yay! Cameras! 🙈🙉🙊┌( ಠ_ಠ)┘ [◉"]
For giggles, I asked Grok about servicing this lens. Pretty general and not sure how accurate. ChatGPT’s answer was similar.
“Disassembling an LTM (Leica Thread Mount) Zunow 5cm f1.1 lens is a delicate process that requires precision, patience, and the right tools. This rare and vintage lens, originally designed in the 1950s, is a complex piece of optical engineering, and improper handling can damage its components or affect its performance. Below is a general guide based on common practices for disassembling LTM lenses of that era, as specific documentation for the Zunow 5cm f1.1 is scarce due to its rarity and the limited production by Zunow Optics. Proceed with caution, and if you’re inexperienced, consider consulting a professional technician.
### Tools You’ll Need
- Precision screwdrivers (small Phillips and flathead)
- Lens spanner wrench (adjustable, with flat or pointed tips)
- Tweezers
- Clean microfiber cloth
- Lens cleaning solution (if cleaning glass)
- Grease for reassembly (helicoid-specific, light viscosity)
- A clean, well-lit workspace with a soft surface (e.g., a microfiber mat)
- Optional: rubber gloves to avoid fingerprints on glass
### General Steps for Disassembly
1. **Preparation**
- Work in a dust-free environment to prevent contamination of the lens elements.
- Take photos or notes at each step to aid in reassembly, as the Zunow 5cm f1.1 has a unique optical design (5 groups, 9 elements, Sonnar-type).
- Ensure the lens is set to infinity focus before starting, as this aligns the helicoids properly.
2. **Remove the Front Retaining Ring**
- Inspect the front of the lens for a decorative or retaining ring around the front element. This is typically threaded.
- Use a lens spanner wrench to carefully unscrew the ring counterclockwise. If it’s tight, a rubber grip or slight heat (e.g., from a hairdryer) may help loosen it without forcing it.
- Once removed, the front element or group may be accessible. Note its orientation (e.g., which side faces forward) as it lifts out.
3. **Access the Optical Block**
- With the front ring off, the front lens group might come out as a single unit. If not, additional screws or retaining rings may secure it—use a precision screwdriver or spanner as needed.
- The Zunow 5cm f1.1’s optical block may separate from the focusing helicoid at this stage. Avoid touching the glass with bare hands; use tweezers or gloves.
4. **Remove the Rear Retaining Ring**
- Flip the lens to the rear (mount side). Look for a slotted retaining ring around the rear element.
- Use the spanner wrench to unscrew it counterclockwise. This ring often holds the optical assembly in place and separates it from the helicoid.
- Be cautious—the rear element is fragile, and excessive force could chip it.
5. **Separate the Helicoid and Mount**
- Once the rear ring is off, the lens may split into two main parts: the optical block and the focusing helicoid/mount assembly.
- Look for small screws or a helicoid key (a pin or guide) on the mount side that regulates focus travel. Remove these screws with a precision screwdriver to release the key.
- Mark the helicoid’s position with a pencil or tape where it separates to ensure proper reassembly later.
6. **Disassemble the Helicoid (If Needed)**
- To access the focusing mechanism fully (e.g., for regreasing), remove the chrome focus ring. This may involve unscrewing additional small screws on the front or side.
- Another retaining ring might secure the helicoid—use the spanner to remove it.
- The Zunow 5cm f1.1 uses a single helicoid (not a double helicoid), which simplifies reassembly somewhat. Note where the threads separate as you turn it apart.
7. **Aperture Ring (Optional)**
- If you need to clean or adjust the aperture, locate the screws or retaining clips around the aperture ring (typically near the middle of the lens barrel).
- Carefully remove these to access the aperture blades. Avoid bending the blades, as they’re delicate.
### Reassembly Notes
- Reverse the steps carefully, ensuring all parts align as they were originally.
- Apply a thin layer of fresh helicoid grease to the threads for smooth focusing, but avoid over-greasing, as it can migrate to the glass.
- Recalibrate infinity focus by adjusting the helicoid key and front guide pins if necessary.
- Test the lens on a camera body to confirm focus accuracy and aperture function.
### Warnings and Tips
- **Fragility**: The Zunow 5cm f1.1 is a collector’s item with intricate glass elements. Even minor scratches or misalignment can ruin its value or performance.
- **Variation**: Early “Ping-Pong Ball” versions (Type 1) and later improved models (e.g., post-1955) may differ slightly in construction. Examine your specific lens for unique features.
- **Expertise**: If fogging or sticky focus is your goal, and you lack experience, professionals like Kanto Camera in Japan (known for servicing Zunow lenses) might be a safer bet.
- **Cleaning**: Use lens-specific solutions and tools for glass surfaces—never use household cleaners.
Since no widely available manual exists for this exact lens, this guide adapts techniques from similar LTM lenses (e.g., Canon 50mm f1.5 or Leica screw-mount lenses). If you encounter unexpected resistance or complexity, stop and seek expert advice to avoid irreversible damage. Good luck with your Zunow—it’s a remarkable piece of photographic history!”
“Disassembling an LTM (Leica Thread Mount) Zunow 5cm f1.1 lens is a delicate process that requires precision, patience, and the right tools. This rare and vintage lens, originally designed in the 1950s, is a complex piece of optical engineering, and improper handling can damage its components or affect its performance. Below is a general guide based on common practices for disassembling LTM lenses of that era, as specific documentation for the Zunow 5cm f1.1 is scarce due to its rarity and the limited production by Zunow Optics. Proceed with caution, and if you’re inexperienced, consider consulting a professional technician.
### Tools You’ll Need
- Precision screwdrivers (small Phillips and flathead)
- Lens spanner wrench (adjustable, with flat or pointed tips)
- Tweezers
- Clean microfiber cloth
- Lens cleaning solution (if cleaning glass)
- Grease for reassembly (helicoid-specific, light viscosity)
- A clean, well-lit workspace with a soft surface (e.g., a microfiber mat)
- Optional: rubber gloves to avoid fingerprints on glass
### General Steps for Disassembly
1. **Preparation**
- Work in a dust-free environment to prevent contamination of the lens elements.
- Take photos or notes at each step to aid in reassembly, as the Zunow 5cm f1.1 has a unique optical design (5 groups, 9 elements, Sonnar-type).
- Ensure the lens is set to infinity focus before starting, as this aligns the helicoids properly.
2. **Remove the Front Retaining Ring**
- Inspect the front of the lens for a decorative or retaining ring around the front element. This is typically threaded.
- Use a lens spanner wrench to carefully unscrew the ring counterclockwise. If it’s tight, a rubber grip or slight heat (e.g., from a hairdryer) may help loosen it without forcing it.
- Once removed, the front element or group may be accessible. Note its orientation (e.g., which side faces forward) as it lifts out.
3. **Access the Optical Block**
- With the front ring off, the front lens group might come out as a single unit. If not, additional screws or retaining rings may secure it—use a precision screwdriver or spanner as needed.
- The Zunow 5cm f1.1’s optical block may separate from the focusing helicoid at this stage. Avoid touching the glass with bare hands; use tweezers or gloves.
4. **Remove the Rear Retaining Ring**
- Flip the lens to the rear (mount side). Look for a slotted retaining ring around the rear element.
- Use the spanner wrench to unscrew it counterclockwise. This ring often holds the optical assembly in place and separates it from the helicoid.
- Be cautious—the rear element is fragile, and excessive force could chip it.
5. **Separate the Helicoid and Mount**
- Once the rear ring is off, the lens may split into two main parts: the optical block and the focusing helicoid/mount assembly.
- Look for small screws or a helicoid key (a pin or guide) on the mount side that regulates focus travel. Remove these screws with a precision screwdriver to release the key.
- Mark the helicoid’s position with a pencil or tape where it separates to ensure proper reassembly later.
6. **Disassemble the Helicoid (If Needed)**
- To access the focusing mechanism fully (e.g., for regreasing), remove the chrome focus ring. This may involve unscrewing additional small screws on the front or side.
- Another retaining ring might secure the helicoid—use the spanner to remove it.
- The Zunow 5cm f1.1 uses a single helicoid (not a double helicoid), which simplifies reassembly somewhat. Note where the threads separate as you turn it apart.
7. **Aperture Ring (Optional)**
- If you need to clean or adjust the aperture, locate the screws or retaining clips around the aperture ring (typically near the middle of the lens barrel).
- Carefully remove these to access the aperture blades. Avoid bending the blades, as they’re delicate.
### Reassembly Notes
- Reverse the steps carefully, ensuring all parts align as they were originally.
- Apply a thin layer of fresh helicoid grease to the threads for smooth focusing, but avoid over-greasing, as it can migrate to the glass.
- Recalibrate infinity focus by adjusting the helicoid key and front guide pins if necessary.
- Test the lens on a camera body to confirm focus accuracy and aperture function.
### Warnings and Tips
- **Fragility**: The Zunow 5cm f1.1 is a collector’s item with intricate glass elements. Even minor scratches or misalignment can ruin its value or performance.
- **Variation**: Early “Ping-Pong Ball” versions (Type 1) and later improved models (e.g., post-1955) may differ slightly in construction. Examine your specific lens for unique features.
- **Expertise**: If fogging or sticky focus is your goal, and you lack experience, professionals like Kanto Camera in Japan (known for servicing Zunow lenses) might be a safer bet.
- **Cleaning**: Use lens-specific solutions and tools for glass surfaces—never use household cleaners.
Since no widely available manual exists for this exact lens, this guide adapts techniques from similar LTM lenses (e.g., Canon 50mm f1.5 or Leica screw-mount lenses). If you encounter unexpected resistance or complexity, stop and seek expert advice to avoid irreversible damage. Good luck with your Zunow—it’s a remarkable piece of photographic history!”
Nick Cecchini
Newbie
We already own the lens so at least that concern is alleviated. I either have to get it repaired or sell it AI. I have a tech who got into it once. We'll probably just choose to be patient with it and try again. It'll make a good challenge piece. I may reach out to Kanto Camera in Japan and start a relationship with them. Thank you very much for you expertise.