I was just thinking I'd like about 20 of these focus mounts, assuming the threads are the same as the original. I'm not taking mine apart...
I will get some close-ups of the lens later, we're getting back to normal after the Blizzard.
The build quality is very high, this is a "they build them BETTER than they used to" lens. The focus action is completely smooth, no "wow and flutter" as you go across the range. No slop in the focus, which means the guide screws fit tight in the guide rails where the helicals are held together. I've replaced guide screws on some J-3's to fix this culprit, and on others just had to fill the guide rails with vacuum pump grease to dampen the play. Someone was paying attention to this area, I've written about it before. The focus is spot on with my M9 across range meaning the focal length has tight tolerance to the Leica spec. I need to get the accuracy within 0.01mm to hit the focus this close. WITH THAT STATED: on the M Monochrom, using an orange filter, you would need to increase the thickness of the shim to account for longitudinal chromatic aberration. I have one layer of copper tape on my 50/1.1 Nokton and 35/1.2 Nokton. I will do this with this J-3+. The sharpness of the lens increases dramatically on the M Monochrom because you get rid of the softness caused by chromatic aberration.
This is with the 1934 5cm F2 CZJ Sonnar, converted to Leica mount. Wide-Open, orange filter.
by
fiftyonepointsix, on Flickr
I held the J-3+ lens and my early LTM Nikkor-SC 5cm F1.4 in each hand- they are about the same weight.
I need to find a scale, and then take it off the M9...
The small set screws look like the ones that Zeiss used in the 1930s. I have a collection of set screws from German, Japanese, and Russian lenses.