Cosina created perfect pair of pancake lenses available for Fuji X mount. First lens is Voigtlander 27mm F2 Ultron, and second is Voigtlander 18mm F2.8 Color-Skopar. In this article I'm going to show how to open Voigtlander 18mm F2.8 lens front area.
Both Voigtlander 27mm and 18mm lenses have exactly same looking frame except slightly different front naming plate. I think it's safe to assume that both lenses should have very similar frame disassembly steps. I've already explored rear area disassembly of Voigtlander 27mm F2 Ultron in Fuji X mount.
There is some amount of facroty applied glue in the front filter thread around front name plate. I'm placing lens facing up first and applying few drops of acetone to filter thread and leaving it for few minutes. After that I'm wiping away acetone remains and using rubber cylinder (hollow in the center) to firm press against front nameplate and unscrew it in CCW direction.
After removing name plate you will see 9 bolts around front lens glass. DO NOT touch three bolts closer to center secured with red glue - that often indicates that front optical frame is factory centered, then secured with bolts and glue. If you unscrew that bolts - optical centering may shift and cause optical quality degradation.
To move forward unscrew three more distant bolts marked with green arrows.
Then remove the front metal circle with aperture marker dot. There is set of three tiny brass shims over bolt sockets, in my lens copy they held in place due to excessive amount of grease. Be very careful when disassembling, I'm only showing lens on camera for article illustrative purpose, but during all first disassembly discovery lens was facing glass up all the time, so shims remain on their original position.
Red arrow is showing position of spring loaded metal ball that works as aperture click stop catcher. Make sure it's positioned exactly there during assembly.
Remove the aperture control ring. Its opposite side has brass contacts secured over plastic plate. They slide over green board shown on lens to the right, that is how Fuji X camera knows which aperture value is currently manually selected.
Red arrows are showing aperture transmission lever set at F2.8 position. It is not possible to move it much further in CW direction, only for about 1mm, which is showing that aperture blades can't physically open more, their back edges start to close aperture circle. It was one thing I was curious about when noticed that aperture blades are still visible at F2.8. Looks like it's just sort of very compact optical design.
WARNING: red arrows also show the large square opening visible from the front. Be careful with tiny brass shims during assembly - they can easily jump out of tweezers and fall into that socket and cause problems inside of aperture chamber.
When aperture lever is moved to closed position the front square opening of aperture lever F2.8 position is even more exposed. It's allowing dust to freely migrate from the front area to optical surfaces in aperture chamber. I'm not sure why this area is not shielded in any way, but it explains why my lens copy (which I purchased used from CameraQuest) already has quite large amount if tiny dust inside.
My recommendation is to always use protective filters on Voigtlander 18mm F2.8 Ultron lens, it will significantly reduce flow of dust to aperture chamber over time.
I'll find more time soon to continue this article with exploring the rear area of Voigtlander 18mm F2.8 lens to see how to clean out dust from aperture chamber, and also to check if there are any mechanical differences to Voigtlander 27mm F2 Ultron lens.
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