C4K and 24fps

[hirohhhh]

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Why does only C4K has 24fps, while all other (5K, 4K and FHD) has 23.98?

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[hirohhhh]

Ok, I asked too early. I just read that it's the standard frame rate of Cinema 4K, so I guess it's not just the Leica's decision not to put 23.98, but it's the way Cinema 4K is.

[scott kirkpatrick]

I'm not expert on this stuff, but the other codecs are video codecs, and to avoid some subtle timing problem, 30 fps in video is actually reduced slightly.  C4K is a film format, so whatever problem the modified frame rate is supposed to solve does not arise.  

[Photoworks]

MOV C4K: 59.94 fps, 50 fps, 29.97 fps, 25 fps, 24 fps
MOV 4K: 59.94 fps, 50 fps, 29.97 fps, 25 fps, 23.98 fps

[BernardC]

13 hours ago, hirohhhh said:

Ok, I asked too early. I just read that it's the standard frame rate of Cinema 4K, so I guess it's not just the Leica's decision not to put 23.98, but it's the way Cinema 4K is.

The 23.98 vs. 24 fps goes back to the dawn of color TV in the US (1950s). The base NTSC frame rate was reduced from 30 fps to 29.97 fps so that color signals would appear on existing B&W sets (with a slight vertical hold adjustment). PAL and SECAM used a different technique, but those systems came-out 10 years later.

Sound cinema was always 24 fps, so that's the C4K standard. Films were slowed-down imperceptibly to 23.98 fps when shown on TV, and then put through a process called "three-two pulldown" to display 29.97 frames (really 59.94 half frames) per second.

"Made for TV" shows were shot at 23.98 fps. I'm sure some were shot at 29.97, but not many because it would have cost a bit more.

Most modern NLEs are able to mix 23.98 and 24 fps on the same timeline, thankfully. I'm not sure how they do it, but I imagine that they adjust the soundtrack's pitch by 0.1% (or whatever the exact ratio is).