The technical index of this lens is 4.6 according to PHOTODO, out of five points.
MMG and MMJ are both multi-mode exposures, but they are made in different places. MMG is produced in Germany and MMJ is produced in Japan.
German Contax, originally a camera brand of carl zeiss under Carl Zeiss, has become a brand of Kyocera Kyocera after many vicissitudes, but blood is thicker than water. Kyocera Kyocera still uses the lens of Carl Zeiss in Germany when using Contax.
There is no essential difference between German products and Japanese products. The products and electronic technology under the name of carl zeiss Company under German Zeiss are all developed in Japan. Carl zeiss, West Germany
The AG part can only do photometry at most, and even the autofocus technology was developed by Bazhou Optics and Sony Corporation, a subsidiary of Kyocera Group. German carl zeiss.
AG has not mastered these technologies. Contax lens can be said to be a combination of German optical technology and Japanese electronic technology. MMG and MMJ are only assembled in different places, and there is no difference in quality.