SLR Gear tested
the ZM 21/2.8 on an NEX-5. Performance with that combination was nothing to write home about.
The ZM 21/4.5 has a nodal point that is much closer to the image plane, so I'd expect it to be worse. Not to say it won't provide usable images, but my guess is that (especially in the corners) a kit zoom would blow the C-Biogon it into the weeds on an NEX sensor.