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25 or 24 fps


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#1 Vincenzo Condorelli AIC

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Posted 08 August 2008 - 03:56 AM

in terms of exposure the difference is minimal, so what's driving the choice of shooting at 24 or 25 fps?

i presume that if you're going for a final print you'd shoot at 24 fps right? but if you're just going for a video master then you'd shoot at 25 fps correct?

what's the standard in the u.s.? and why is it different from europe?

thx...
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#2 Stephen Williams

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Posted 08 August 2008 - 04:00 AM

in terms of exposure the difference is minimal, so what's driving the choice of shooting at 24 or 25 fps?

i presume that if you're going for a final print you'd shoot at 24 fps right? but if you're just going for a video master then you'd shoot at 25 fps correct?

what's the standard in the u.s.? and why is it different from europe?

thx...


Hi,

European power is 50Hz, which is the reason many but not all people shoot at 25 fps in Europe. In the US people shoot film at 24 and digital at 23.987.

Stephen
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#3 Vincenzo Condorelli AIC

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Posted 08 August 2008 - 04:13 AM

thx for the explanation stephen...so whether you're going for a final print for teatrical release or just a video master does not make any difference in this domain right?
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#4 John Sprung

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Posted 08 August 2008 - 05:30 PM

In the early days of television, interference from the AC power system was a big problem. So big that the engineers decided to set their field rate equal to the power frequency. That results in the interference being a stationary rather than a moving artifact. So, in the 50 Hz countries of Europe, TV runs at 25 frames per second. Here in the 60 Hz USA, it's 30 frames per second.

The theatrical film business got started long before TV, and standardized on 24 frames per second when sound was introduced in the late 1920's.

All that works out quite well for European TV, because you can shoot at 24 fps and show it on TV just a tiny bit fast at 25 fps, or vice versa.

Here in the USA, 24 fps film is converted to 60 field video by 3-2 pulldown. One frame of film is transferred to three fields of video, the next to two fields, then three again and two again, over and over. European 25 fps material goes through the same process here, slowing it down to 24 and then applying 3-2.

The "point nine something" business here happened because of a problem discovered at the last minute in the development of the color add-on to NTSC. The new color subcarrier was interfering with the existing sound subcarrier. That could be fixed by shifting one of them just a tenth of a percent. They chose to shift the color subcarrier, which meant having also to shift the line and field rates. So, instead of 60, 30, and 24, what we really have is 59.94, 29.97, and 23.976. Because of that, we later had to have drop frame time code. It also makes power frequency interference theoretically a moving artifact, but it moves too slowly to matter.



-- J.S.
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#5 Igor Ridanovic

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Posted 08 August 2008 - 06:52 PM

One important fact of life for North American filmmakers is that although some digital cameras allow you to shoot 24fps it is much better to stick to 23.98fps from post production standpoint.

This is an unfortunate legacy of post production equipment and may change in the future. For now you'll save yourself time and money by shooting in 23.98p even if you're aiming for a theatrical release.

Another amusing fact is that Hollywood films run shorter in Europe due to the fps change that J.S. explained.
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#6 Vincenzo Condorelli AIC

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Posted 11 August 2008 - 03:51 PM

thank you all for the excellent explanation...
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