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Shooting different speeds simultaneously


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#1 Ashim

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Posted 20 January 2007 - 02:15 AM

Hi,
It feels good to be back with the forum AND
I REALLY NEED to ask you this.

Is there some mechanism where the camera can shoot three different speeds( 12, 24, 48fps)
simultaneously. I am not suggesting ramping.

Two boxers are slugging it out in the ring
And a single camera captures their actions at different speeds in one single shot.


Thanks.
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#2 David Mullen ASC

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Posted 20 January 2007 - 02:53 AM

No, that's not possible. You can't basically shoot three different shots at the same time with a single camera. How can a single motor running a single piece of film run at three different speeds simultaneously? You'd need a time machine to do that, or some other method of breaking the laws of physics.

You would probably have to shoot at the highest frame rate desired so you get the most information and then try and create the other lower speeds from that footage. Or shoot at the middle speed and then slow it down and speed it up in post to create the other speeds.

Ashim, it's time you edited your Display Name (go to My Controls) to be a first and last name as per the forum rules now.
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#3 David Sweetman

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Posted 20 January 2007 - 03:13 AM

Yeah, if you just shoot at 48 fps you basically have 24 fps and 12 fps. Take out every other frame and you've got 24, every other again and you've got 12. You'll have to open up the iris or shutter more than you would if you were shooting real 24 or real 12 though.
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#4 Keneu Luca

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Posted 20 January 2007 - 03:54 AM

Yeah, if you just shoot at 48 fps you basically have 24 fps and 12 fps. Take out every other frame and you've got 24, every other again and you've got 12. You'll have to open up the iris or shutter more than you would if you were shooting real 24 or real 12 though.


That wouldnt exactly be doing what he's asking. He would be filming at just one speed. He specificaly asked to shoot at three different speeds.

Is there some mechanism where the camera can shoot three different speeds( 12, 24, 48fps)
simultaneously.


Although, filming at a high frame rate and then playing back at several different speeds would seem to give the result he's looking for, if I understand what he wants. Maybe I don't.

Maybe he can go in depth as to what he needs.

Edited by Keneu, 20 January 2007 - 03:56 AM.

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#5 Scott Fritzshall

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Posted 20 January 2007 - 04:51 AM

Maybe he can go in depth as to what he needs.

He needs a magician or possibly a wizard.
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#6 Charlie Peich

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Posted 20 January 2007 - 11:21 AM

Here's a simple way to shoot the same scene at 2 different speeds... 2 camera rig

Then he could combine the 2 pieces in post. Is this what he's thinking? :unsure:
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#7 David Mullen ASC

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Posted 20 January 2007 - 11:47 AM

Sure, you could do it with an over-under 2-camera rig like Clairmont has, but if the point was simply to shoot one event at three different speeds, not line them up precisely, then it would be easier to just use multiple cameras.

Extracting 24 and 12 fps from 48 fps would be the same as shooting separately at 12, 24, and 48 except for the motion blur per frame. The extracted 24 fps would look like you used a 90 degree shutter angle and the 12 fps extracted would look like you used a 45 degee shutter angle -- since everything was shot with a 1/96th of a second shutter speed.
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#8 Phil Rhodes

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Posted 20 January 2007 - 01:11 PM

Hi,

I've been doing a lot of pseudo-timelapse recently, shooting a lot of video tape and speeding it up in post, usually 3000-5000%. Modern software will compile frames quite nicely (though slowly on that sort of speedup), providing accurate motion blur.

It's surprisingly rare to find anything that produces objectionable dot-and-dash artifacts because of the 50% shutter cycle, even when speeding up things that are moving normally.

Phil
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#9 Nadav Hekselman

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Posted 21 January 2007 - 01:16 AM

Ashim,

Maybe you mean changing the speed while shooting?

Its used in movies like "Raging Bull". Moments in which the same shot is going briefly into slow-motion and than comes back to normal speed.
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