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Old December 23rd, 2010, 08:20 AM   #1
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Why do we need 120 / 240 / 600 hz Televisions

I have recently been reading articles that report side by side comparison of 120hz LCD televisions, the articles claim they are no better than the original, which I am guessing is at 60hz. I never questioned the technology, I just accepted it because tech was getting better, faster refresh rates sounded better.

As I thought about the photography end of it I realize we shoot 60 / 50 / 30 / 24 fps. So why do we a refresh rate so much larger than the number of frames that we capture? Tube televisions had and still have some qualities much higher than newer technology. I prefer my old HD sony 200 lb clunker to the newer LCDs. I just don't have to worry about screen burn, motion blur, etc. Why are fast action football games in need of higher refresh rates if we are shooting no more than 60 fps ??
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Old December 23rd, 2010, 09:33 AM   #2
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So the manufacturers can sell more TVs and make more money?!?!? ;-)

Great question with my smart aleck answer but honestly isn't there a point of diminishing returns? Maybe there is I don't know but it just seems that as long as people are willing to spend the money the manufacterers will continue to build the "next best thing". Maybe I'm just a grumpy old man tired of spending dollar after dollar. Then again, maybe I'm on to something. It sure seems like you are. Why DO we need the 600 refresh rate if were shooting a frame rate far less than that?
Dunno. Don P. now you have me asking the question and it's gonna bug me. <sigh>

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Old December 23rd, 2010, 09:47 AM   #3
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for 3D and most program shot for TV are 50i 0r 60i
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Old December 23rd, 2010, 10:20 AM   #4
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Quote:
Originally Posted by Don Parrish View Post
I have recently been reading articles that report side by side comparison of 120hz LCD televisions, the articles claim they are no better than the original, which I am guessing is at 60hz. I never questioned the technology, I just accepted it because tech was getting better, faster refresh rates sounded better.

As I thought about the photography end of it I realize we shoot 60 / 50 / 30 / 24 fps. So why do we a refresh rate so much larger than the number of frames that we capture? Tube televisions had and still have some qualities much higher than newer technology. I prefer my old HD sony 200 lb clunker to the newer LCDs. I just don't have to worry about screen burn, motion blur, etc. Why are fast action football games in need of higher refresh rates if we are shooting no more than 60 fps ??
The reason for the 120Hz televisions is the simple fact that 24 fps does not divide evenly into 60Hz. Have you ever watched 24 fps material on a 60Hz set? If you did, you got considerable (and often objectionable) judder. 24 fps, however, does divide evenly into 120Hz (or 240Hz or 600Hz, for that matter); therefore, frames can simply be electronically duplicated on such higher-Hz sets.
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Old December 23rd, 2010, 10:23 AM   #5
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But aren't tube tv's 60 hz ?? Movies don't seem to have a problem and they are 24 fps ?? It is advertised that sports will not display well on the regular LCD sets.

I thought that 3:2 pulldown was for that , intermixing frames to create the correct number ??
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Old December 23rd, 2010, 10:29 AM   #6
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Don,
Most TV's didn't play 24PS material at the native frame rate but were converted to NTSC 29.97 (in the US).
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Old December 23rd, 2010, 10:31 AM   #7
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Daniel, was this something the broadcasters did ? thanks
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Old December 23rd, 2010, 11:40 AM   #8
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Don,
It depended on the source of the movie. If they were using a film chain and showing the film live then it happened there. Most films shown on broadcast were/are played back as video and the people who transferred the film to tape would do it as tape didn't have a 24FPS option until relatively recently.
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Old December 23rd, 2010, 03:30 PM   #9
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Originally Posted by Don Parrish View Post
Daniel, was this something the broadcasters did ? thanks
The conversion (at the time using entirely analog video equipment, which was incapable of capturing or reproducing a vertical resolution of more than 480 interlaced lines) was done at the distribution end (for network showing and/or syndication). The broadcasters simply made dupes of those copies that had been prepared for distribution.

These days, the TV shows are shot mostly with digital equipment - and yet whomever was in charge of the shoot still insisted on using 24p for most of them. However, copies sent to broadcasters is still converted from 1080/24p to 1080/60i or 720/60p at the distribution end - only this time using digital equipment. The quality of the conversion (as aired on local stations) varies widely (for example, programs that originally aired in 1080/60i on NBC and reaired at a later date in 720/60p on my city's local MyNetworkTV station suffered from severe judder).
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