Leica Carl Zeiss Jena 5cm F2 Sonnar Teardown-

[Brian]

I had these instructions posted on the old Zeiss Ikon user forum, long gone. I lost the original pictures- so took a new set on the last one that I converted to Leica mount.

 

[Brian]

Everything finished, re-assemble in reverse order. The taps for the set screws show where everything should screw in, but make some scribe marks to indicate the positions before they get covered up by the rings being screwed back into place.

 

[carlb]

Excellent breakdown, Brian. How would one fine adjust for focus?

 

[Brian]

I've built up a collection of shims from buying parts lenses, adjusting J-8's, and converting lenses to Leica mount. It's easiest to use a digital camera to check focus, but i aslso have a TTL viewer for M39 mount lenses,

In short: you need to determine focus with the Rangefinder to a test object, 1meter is a good range. Use a ruler or tape measure, something that you can determine where actual focus is. Once you get the error, you can compute the increase in the thickness of the shim to correct back focus, or decrease to correct front focus.

I sent Jason Howe the instructions for the J-3, which has the formula in it.

http://aperturepriority.co.nz/wp-content/uploads/2013/02/Jupiter-3-Shimming-Instructions.pdf

I made an Excel spreadsheet for shim adjustment and for adjusting focal length.

Using the retaining ring as a variable shim- figure 0.5mm for a full rotation, and use it for fine adjustments. If you unscrew it too much, the aperture ring will be too loose.