I just played around with my new vintage lens that's over 50 years old, and I'm surprised at how sharp it is, even when connected to a teleconverter.
Gear:
• Sony α6400
• Carl Zeiss Jena Sonnar 135 mm f/3.5 (3rd version, zebra, early 1970s)
• Soligor Auto Tele Converter 2X to fit Pentax M42 (Japan)
• K&F M42-Sony E Adapter