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SYNCING MUSIC TO 8FPS


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#1 Sasuke

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Posted 25 May 2006 - 11:16 AM

Hi,


I am shooting a music video at 8FPS and I need the music to sync. I know that if I
want to shoot slow motion for sync, I have to speed up music playback to
match in post. Does the OPPOSITE apply to framerates below 24fps? I am
shooting on 35mm.

Thanks
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#2 Michael Nash

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Posted 25 May 2006 - 10:13 PM

When the camera speeds up, the music has to speed up to stay in synch. When the camera slows down, the music has to slow down to stay in synch.

8fps is 1/3 "normal" 24fps. The music has to be slowed to 1/3 speed.
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#3 Sasuke

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Posted 26 May 2006 - 08:39 AM

When the camera speeds up, the music has to speed up to stay in synch. When the camera slows down, the music has to slow down to stay in synch.

8fps is 1/3 "normal" 24fps. The music has to be slowed to 1/3 speed.




Thanks Michael. That really helps. One more question: Will I have to the lens aperture 1/3 to
compensate for speed change? As far as I know, I would only have to do that for speeds
above 24fps(48,96,128).
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#4 Stephen Williams

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Posted 26 May 2006 - 08:48 AM

Thanks Michael. That really helps. One more question: Will I have to the lens aperture 1/3 to
compensate for speed change? As far as I know, I would only have to do that for speeds
above 24fps(48,96,128).


Hi,

8fps is 1.5 stops brighter than 24fps. 48 is one stop darker than 24.

Stephen
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#5 Michael Nash

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Posted 26 May 2006 - 09:01 AM

You'll have to close down the iris 1 and 2/3 stops for 8fps.

Any time you change the speed that the film runs through the camera (frame rate) you're changing the exposure time for each frame. If you double the frame rate, you cut the exposure time in half -- so you need one more stop of light to compensate. If you cut the frame rate in half (12fps), you're doubling the exposure time per frame, so you compensate by closing down one stop. Half of 12fps is 6fps; requiring one more stop. But 8fps is only 2/3 of 12 (not half), so the total is 1-2/3 stops.

Double check my math; I haven't had my coffee yet. :blink:
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