So, in this article, I'm taking apart my Voigtlander 40mm F1.2 NOKTON Aspherical, one of Cosina's latest ultra-fast lenses.

There are a few minor specks of dust in the midsection that don't affect anything, but I'm just really curious about the mechanics of this CV 40mm F1.2 :) so that's reason enough.

The reason I use the Voigtlander 40mm F1.2 with Leica mount is because it can be easily adapted to multiple systems - Sony A7 and Fujifilm using simple adapters. It's also a much more compact lens than the Sony E version.

Disassembly steps

So, the first step, of course, is to carefully unscrew the four mounting bolts using a special flat screwdriver. Please note that it must have parallel surfaces, otherwise the groove for the bolt head will be slightly deformed with a conventional flat screwdriver. I used a metal file to adjust the surfaces of the screwdriver.


Then remove the mounting ring and thin shim.


It was a big surprise to see three helical rails! Two of them are actually focus guides, the third in the middle is part of the helicoid of the rangefinder pair, which is separated from the focus - a very clever solution from Cosina.

First, focus the lens to the minimum distance (0,5 m) and set the aperture to F1,2. We need this to remember the position of the helicoid for assembly. The F22 mark should be near the infinity mark.

Unscrew the 4 black screws with a screwdriver and note their exact position so you can put them in the same place during assembly. Please note - there is a fixing adhesive that will break when unscrewed - do not remove it, it must remain in order to exactly match the position of the brass guide during assembly.


Just look at those huge thick brass rails - designed to last a long, long time. Now it's time to carefully unscrew the entire focusing body from the lens optics clockwise (CW). Without rotating the focus ring, grasp the body of the frame and slowly unscrew it until the F22 mark reaches the 0,6 m mark. This is exactly the position that you must return everything to during assembly.


Pull out the focus frame. That's interesting - I see the diaphragm drive pin there, it seems that if I ever need to remove the diaphragm ring, most likely the front plate can be unscrewed counterclockwise, but today I will not do this - there is no need.


An extra look at the focus frame - just look at how much brass there is.


Now carefully unscrew the entire rear lens assembly counterclockwise, holding it at its widest part.


Speaking of disassembling the focus ring, my sample Voigltnader 40mm F1.2 has factory glue on top of the black retaining ring (one of the areas is shown in red). It is not necessary for me to break this glue and unscrew the ring, but if you need it, try to find a glue solvent (like acetone) and then unscrew the ring with a ring wrench.


The third helical guide disc serves the rear cylinder of the rangefinder transmission. Here you can see that the brass cylinder has two separate threads - the top one for the focusing core and the bottom one for the rangefinder drive.


Assembly stages

To assemble the Voigltander 40mm F1.2, screw in the optical module clockwise, then set the 0,6m focus frame mark to match the F22 aperture ring mark. Then engage the spiral threads and slowly turn the lens counterclockwise until F22 stops below the infinity mark. If this does not happen, it is necessary to unscrew the frame and hook the thread closer to the 0,6m mark.


Look inside the slots for the brass guides, adjust the position of the focusing ring slightly, and insert the guides exactly where they were before. The orientation of the outermost guides is the opposite of the middle guide. Then insert 4 black bolts into their original places and screw them in, but not completely. Try focusing the lens a little back and forth until there are red glue marks on the brass rails, perfectly positioned next to the bolts, then tighten the bolts.


Check again how the focus ring moves in the horizontal position of the lens - it should move smoothly, as before disassembly. If not, slightly unscrew the guide bolts and rearrange the guides, then tighten the bolts and check again.

Finally, put the calibration washer and support ring, screw in all four mounting bolts, also not completely. Center the mounting ring by rotating it, then tighten all four mounting bolts.


It was a pleasure to explore the aspherical mechanics of the Voigtlander 40mm F1.2 NOKTON lens and realize that it is very well made with high precision and durable components. The mechanics of the Voigtlander are relatively easy to disassemble and maintain. Access to the internals is very easy and does not affect the optical alignment of the lens.

Some photos from Sony A7s and Fujifilm X-T30

The main strength of the Voigtlander 40mm F1.2 Nokton is its good depth of field and OOF control in the frame, which I really like.


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