The MTF data for old C/Y Distagon 28/2 T*:
http://www.zeiss.com/C12567A8003B8B6F/E ... 28mm_e.pdfThe MTF data for new ZF Distagon 28/2 T*:
http://www.zeiss.com/C12567A8003B8B6F/E ... 8ZF_EN.pdfAn obvious, huge improvement at f/2 already! While the ZF at f/4 also shows better performance on micro-contrast (40lp/mm lines) than the old C/Y Distagon 28/2 T*
I would say the ZF is an improved version from the C/Y (in which many similarities can be found from their design!). The better performance of the ZF at wide open aperture should be contributed by the new production method and better accuracy for the ZF lenses.
Anyway.........a floating element Zeiss lens = Must Buy!