Why do we have fields anyway?

[stiej]

Hi,

Film doesnt utilize fields -it's progressive at 24 frames per second. TV is interlaced and therefore uses fields, (25 or 30(or 29.97) frames per second with 50 or 60 (or 59.94) fields per second)?

Why are fields used?

Is it because somebody thought the they can get extra smoothness in motion without messing around with the frames per second rate?

Is this the only reason why fields are still utilised? If they were got rid of, would we be harmed? Or, on the other side of the coin, why hasn't film taken on the fields approach (i.e having 48 fields per second to complement its 24 frames per second frame-rate)? Is this because film is expensive anyway, and therefore progressive techniques are favourable in that less celluoid in itself is used per second of shooting?

Why did somebody not recommend recording everything progressively from the very beginning but at double any regional frame rate - i.e not using fields, just full complete frames and lots of them. This I would think achieves the smoothness that fields can provide with the extra that none of the frames are constructed from any amount of half-frames.

Steven Jones

 

[icrf]

I think it is a way to get a smoother image without the incredible expense of increasing framerate. A TV uses a cathode-ray tube (CRT) like most computer moniters. Have you ever set your moniter to 60Hz? You get a horrible flicker that's difficult on the eyes. 60Hz is 60 times a second that the moniter image refreshes...double that of NTSC TV.

So how does TV do it? It displays the odd numbered lines of a frame on the screen while it updates the even numbered lines, then odd, even, etc. This gives the refresh the smoothness illusion of 60Hz without the flicker (since the screen is never completely blank) at only 30fps of source.

This is how I understand it, but like everything in life, it could be wrong. ----------------------------------------------------------------------------------
...but I'm just a C man trying to see the light