I'll start with the classic set of steps - dismantling the back and gaining access to the focusing mechanics. This sample of the Voigltander 15mm F4.5 III lens has a little play on the focus ring, so I want to fix that.
At first I examined the rear area of the lens, but did not see the ring that fixes the lens block of the lens inside the focusing mechanism, as is done in the CV 40 / 1.4 or CV 35/2.
I realized in a few days that the protruding black cylinder is not part of the frame of the rear lens assembly, but is exactly the retaining ring that I was looking for :) There may be glue on the threads, so I'm ready for this and I'm going to use: acetone, rubber ring for strap (cut from a bicycle tire tube).
I'm not going to use a box wrench to avoid damaging the metal ring. Instead, I use a rubber ring. But first, you should unscrew the four silver bolts and remove the mounting ring for easier access. The lens is focused to the maximum distance so that the ring of the rangefinder pair is curled inward.
Now I wrap the rubber ring around the barrel of the rear lens barrel. Also, I use a syringe to gently apply a few drops of acetone to the inside wall of this ring so that it drips onto the glued thread. Then I wait a minute or two and unscrew the ring.
The lens may be disconnected at this point.
There is a set of brass shims around the lens block for precise focus calibration. The green arrow shows the metal pin and the corresponding position for lens assembly. If the diaphragm ring requires service, there is now access to remove the diaphragm drive mechanism. But I'm not doing that today (the aperture ring works perfectly), instead I'm going to inspect the focus ring drive.
It looks like the brass piece has some play when it's moved horizontally. To fix the backlash, I use pliers. It is necessary to increase the width of the brass guide plate precisely and accurately. It's hard to explain this process in an article, but the goal is to keep the geometry the same but make the end of the guide slightly wider (about 0,05-0,01mm). After correction, the plate with it should move freely inside, but without play. Then I add lubricant to the part and put it back together.
After connecting the focusing mechanism and fixing it, I focus the lens on the infinity mark and clean the cylinder of the rangefinder pair (marked with a green arrow). Also, out of curiosity, I remove the depth of field scale ring, after unscrewing the four black bolts.
By removing the depth of field scale ring, you can lubricate the area of the focus ring movement limiter.
Dismantling the front
The Voigtlander 15mm F4.5 front plate must be removed first. It sits on the filter threads and can be further secured with glue, so put a few drops of acetone on the filter threads first.
Then cut four small pieces of sticky foam and stick them between the text areas on the front panel (sticky foam can remove lettering paint, so don't cover the letters with it).
Then take the back cover of the Voigtlander, carefully center it and attach it to this tape :) This will keep the glass in the center away from the surface of the cover.
Press firmly and unscrew the front panel counterclockwise.
I wipe the remaining acetone / glue from the filter threads and the edges of the nameplate.
Now we unscrew the three black bolts located closer to the filter thread.
Then remove the lens hood frame. At this point, you can also remove the other three screws and remove the entire front glass section to gain access to the diaphragm. But don't do this unless absolutely necessary - the front optic is precisely centered for proper optical alignment, and even slight misalignment can cause optical misalignment.
IMPORTANT: After removing the lens hood ring, DO NOT place the lens down as the front glass protrudes and can be easily scratched.