[cheschire]

50Hz is what European power runs at, as opposed to North American 60Hz. This had some correlation to the analog film frame rates being 25 fps in Europe and nearly 30 fps in America, though I’m not entirely sure what the cause was.

Nowadays it’s probably a performance / battery saving “feature” attempt.

[Findecanor]

TV signals (PAL and NTSC) were 50 and 60 Hz so as to be in sync with the flickering of electric lamps.

When film is converted to 50 Hz TV, the film is sped up 24->25 fps and every frame shown twice. When converted to 60 Hz TV, there is "2:3 pulldown": every even frame is shown twice, every odd thrice. (Actually, both PAL and NTSC have interlaced video modes, with only every other line updated each frame, so as to conserve bandwidth.)

BTW, when 60 Hz computer monitors were introduced in Europe and used in office spaces with fluorescent lights with passive ballasts that flickered at 50 Hz, some sensitive users suffered headaches from using the computer screen for too long. These days, both fluorescent lights and LCD backlights tend to flicker at much higher frequencies that it isn't much of a problem.

[jdub]

Nah, not film rates [1], video: NTSC is 30fps and PAL is 25fps because the cathode ray tube scan rate was built around AC power cycles. When low fps truly Hz. Sorry.

[1] generally 24fps because that is culturally what film looks like and people get very weird whenever anyone tries to fuck with it

[toast0]

I'll allow your joke, but NTSC is 60 fields per second, and PAL is 50. Certainly a large portion of content came from film and in PALworld would be shown as even and odd halves of a frame, or in NTSCland as 3 halves of a frame, then two halves...

But actually interlaced content exists too. Each field is independent, there's no frames to speak of.

Early video game systems based on NTSC/PAL ran at 60 fps or 50 fps, but ran off-spec signals to always hit the same half of the display lines (odd or even). 4th gen systems (genesis/mega drive and snes/sfc) had a few games that used interlaced output; later systems had many, running PAL@60Hz became a common option too.

[jdub]

When confronting confusion between film and video, I wasn't about to get into FIELDS per second. :-D

[brk]

Not only was it built around AC, the technology at the time only allowed for roughly 1/2 the AC cycles rate. People think there was some great reasoning behind 30fps. It was just what was available, essentially.

[fragmede]

The original black and white NTSC was 30/60 Hz but was changed to 29.97 fps in order to be backwards compatible with black and white TVs.