It's my first owned and exploratively disassembled lens in Nikon Z mount and it's great to work with Voigtlander product due to lots of expected similarities with Fuji X mount Voigtlanders I explored before.
Article is showing how to clean dust and debris from the aperture chamber of Voigtlander 40mm F1.2 Nokton lens. Yeah, it's a common "disease" of almost any lens that has manual aperture control, biut does not have dust sealing of that area. Dust is normally migrating inside over time, and sometimes it's not a dust but drying out aperture mechanics grease.
Disassembly steps
I decided to open Voigtlander 40mm F1.2 lens from the rear area. The Nikon Z mount lens has electronic contacts, but mechanically it should be much more simple build comparing to the Leica M mount version of 40mm F1.2 Nokton I successfully CLAed in the past.
At first you need to unscrew four silver bolts of the lens mount ring. They may be resistive due to factory securing glue so be accurate.
Next step can be unscrewing three small bolts on the mount outer sides to release inner black tube and lens contacts frame. I didn't notice that during the first disassembly, so simply gently elevated mount ring, found the ribbon cable connector on the board and unlocked it (by lifting black lock) and extracted ribbon cable.
IMPORTANT: There is a very tiny connector of the aperture ribbon cable, the socket also has black lock plate that need to be gently elevated first. Then release the ribbon cable, it's very thin and fragile so be extremely accurate.
There is set of precise infinity focus calibration shims made of thin metal. I have three of them in my Voigtlander 40mm F1.2 Nokton lens.
Unscrew two silver bolts ant take out the electronic board.
Taking a close up look at the electronic board to make sure there are no any signs of water or metal dust particles. The reverse side is flat and has no electronic components.
Unscrew three black bolts to release the DOF ring.
Lift up and remove the DOF ring.
WARNING: After removing DOF ring the focusing can be made outside of normal operating range. Do not rotate focus ring outside that range due to helicoid thread may disconnect if 0.3m marker pass the F4 aperture mark (when aperture is set to F1.2).
There is a white plastic stopper cylinder inside focus frame limiting focusing rotation when bumping to DOF ring elevated area shown on picture below.
Now there is a bit tricky step - another set of three black bolts need to be unscrewed, though they sit quite deep inside so you need long screwdriver. Standard precision JIS screwdriver pictured above will work though.
Accurately elevate the focusing frame from the lens core frame. There is pair of brass contacts for aperture position detecting.
The opposite side of focusing frame has resistor board capturing the aperture position contacts and transferring that info to the electronic board over thing aperture ribbon cable.
It looks exactly same as aperture position reading unit in Voigtlander lenses made for Fuji X cameras.
I didn't point attention when reading about Voigtlnder lenses in Z mount, but looks like lens does not have electronic component to transfer the focusing distance information, or perhaps I don't see it during this disassembly.
To access aperture chamber for cleaning you need to loosen the factory glue. I'm using acetone delivered to the area shown on the picture below. Need to wait for aminute or two, Then accurately unscrew the whole optical core rear frame in CCW direction by holding larger glossy metal cylinder with a rubber strap.
ATTENTION: set lens aperture ring to F1.2 and hold the front filter thread frame and make sure aperture remains at F1.2, while unscrewing the optical core frame.
Use air blower to remove dust from the inner optical surfaces. You may also want to close/open aperture to check if any dust is on the blades. Involve a strong LED light to inspect surfaces for micro dus by looking under different light angles.
Assembly details and hinta
Bonus Content - DIY expanding close focus a bit...
With DOF ring removed the focusing ring is able to rotate further than the stock 0.3m distance.
BEWARE: the helicoid thread is detaching after 0.3m mark is reaching the F4 value (with aperture set to F1.2). It is quite difficult to connect thread back, so do not rotate focus ring further unless you need to disassemble that area for greasing.
NOTE: The aperture ribbon cable is attached to inner wall of focus frame with adhesive, it need to be accurately detached if you need to disassemble focus ring.
As you can see on the picture before, focusing closer than 0.3m is exposing a wide gap between focus ring and apertue control ring shell. I'm not interested in extra focusing distance at this cost of introducing extra dust inside. Though there is still a bit of rotation past 0.3m while there is no gap, and I'm going to extend focusing by that small distance. It's important to measure precisely the amount of material to be cut, with few atttempts average measurement is showing 4.5mm.
I'm grabbing some masking tape and covering all the surface except small area to be grinded. Next step is to use precise metal file to cut off about 4.5mm wide rectangular area.
Re-assembled lens is now able to focus a bit closer than stock 0.3m. The focusing shell keep covering the aperture control ring shell at this point.
Tinkering with photo equipment is my big hobby. It's often quite challenging to explore disassembly steps or designing new useful accessories, but also a joy to share them later with people. I keep these activities apart from primary work, though appreciating a small tips for a coffee if you find my shared results useful.