In this article, I take a look at one of the latest Leica M mount portrait lenses, the Voigtlander 75mm F1.5 Nokton Vintage Line.

I'm taking this opportunity to share details of lens construction in case you need to do some DIY repairs.

The Voigtlander 75mm F1.5 portrait lens is already well known for its excellent image reproduction and high level of detail wide open. The optical design consists of elements with partial dispersion and aspherical elements, more details can be found on the official website Voigtlander . What is curious about this lens is its relatively light and thin lens barrel compared to the large amount of large glass inside.

Cosina engineers designed this lens to fit the latest Vintage Line models, which have bodies closer to the 1950 release. This makes the Voigtlander 75mm F1.5 very unique. On the other hand, this uniqueness makes components harder to assemble and harder to figure out how to safely disassemble them. It took me a few days to figure out how to do it right.

Disassembly

Traditionally, I will start by unscrewing the four bolts and removing the Leica M mounting ring.

And here the "magic" begins - I do not see the retaining ring holding the lenses inside the frame. I assumed that the retaining ring is inside the rear optical tunnel. If you focus the lens and see how the rear moves, you will get some information about the mechanics of the build. So I assumed that the next ring was what I needed. Cosina like to add some glue to the fixing rings, so I put a few drops of acetone on the inside wall of this ring and spread it along the bottom, tilting the lens barrel.

This ring is difficult to access with a box wrench, and even if you do, there is a very high chance of ripping off the edges of the ring because they are very thin. There are several safer ways to unscrew retaining rings by hooking on the surface area, and today I use one of the exotic methods - unscrewing the ring with ... a plastic bottle.

Well, I use this bottle simply because the diameter of its neck is slightly smaller than the diameter of the retaining ring. For an effective grip, I add a layer of thick rubber band between the bottle and ring surfaces and gently press the bottle inward for a good grip. It looks intimidating, but it's actually safe, because the plastic of the bottle is soft and the paint is protected by a rubber layer.

Strong pressure and a few quick counter-clockwise movements with high torque loosen the retaining ring, then I unscrew it. It is not surprising that the ring is not removed from behind, because. the inner diameter of the rangefinder coupling ring is somewhat narrower than it. So I just take off the bottle and the gum and carefully lift the focusing frame up.

Note - Radial shims are available for accurate focus calibration. During assembly, they should be located directly above the rear optical frame. The retaining ring remains inside the focus frame, apparently it cannot be pulled out from below.

At this point, you have full access to the focus mechanics. The next step is to note the position of each bolt, unscrew the four of them holding the brass focus guide rings, and remove them.

Then I unscrew the four black bolts in the mounting area and remove the focusing core.

Pay attention to the bright silver bolt on the edge of the inner focusing core - when assembled, it must match the corresponding socket of the optical lens core, and its position corresponds to the infinity point of the focus ring (when it is turned to infinity).

If you turn the focusing mechanism, it will turn up and allow you to check the condition of the lubricant.

The next step is to unscrew the silver focus ring bolt.

Then unscrew the focus ring from the base by two full turns counterclockwise.

At this point, you have access to the threads of the focus ring, which here require a relubrication. I also made a small adjustment to the geometry of the focus ring, it had a moderate impact to the side, which resulted in a slight elliptical shape and caused the threads of the focus ring to wear more actively. Now the ring spins exactly like new and I collect everything back in reverse order.

A few important notes on reassembly:

  • Screw in the brass focus guide rings, but do not tighten the bolts, then move the brass guide closer to the center of the focus core and screw them in. Make sure the focus ring rotates without play.
  • Make sure the slightly cut surface of the rangefinder connector ring is close to where the rangefinder ring is cut.

Brief conclusions

The mechanics of the Voigtlander 75mm F1.5 lens are solid and very well designed for ease of maintenance, although the first retaining ring is quite difficult to unscrew. It's nice to see the brass guides in the focusing ring and the spiral design, which have the ability to adjust their position for higher movement accuracy. The optical frame is beautifully made, and it seems that there is access to the aperture ring from the back.

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