[old_tv_nut]

Regarding recording one video field per film frame at 60 fps:

This introduces terrible problems, as the scan lines in the telecine have to match the scan lines in the kine recorder, or you get terrible moire. This means that the optics at both ends have to be completely distortion-free, the scan heights and vertical linearity must match perfectly, and so on.

The CBS Electronic Video Recording system, introduced in the late 60s/early 70s, did use 60 fps, on microfilm, but recorded a full video frame every 60th of a second using a field memory at the recording site (just barely technically feasible at the time). In addition, the master was recorded by electron beam, and the beam was wobbled up and down at 14.31818 MHz (four times NTSC color subcarrier) just enough to fill in the blank spaces between scanning lines, so there was no line pattern on the film to cause moire.