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Slow Motion Info needed
Hey All,
So here is my question:
I need to shoot some slow motion video of a speaker driver moving back and forth for an interactive Sound course I am producing. I will be using 120hz so the speaker will be moving at 120 cycles per second. All my cameras shoot in 1080i. So to capture the best that I can to be slowed down in Vegas…what should I set my camera at?
Shutter Speed?
Should I shoot in 1080i HDV or go to DV-SD? (The screen res will be lower than SD anyway
Vegas time stretching…any thoughts?Thanks for your help in advance!!
Scott Francis
Mind’s Eye Audio/Video Productions -
6 Replies
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Try and borrow a 60p camera or spend $120 on a Kodak Zi8 just to shoot the speaker. There is no substitute for having more frames to begin with. Also shooting 60p will give you progressive footage so that interlacing doesn’t cause motion problems.
If you can’t do this, then use a shutter speed of 120+ so at least the frames you do get won’t be blurry. I would plan on using Interpolate to deinterlace the footage to get it as smooth as possible.
Having said that, Eugenia’s blog has a very convincing method of turning 60i to 60p for some very smooth slo-mo. I haven’t tried it yet but you probably should. Read this: Butter-smooth slow motion and use Method 2 which is the easiest for Vegas editors.
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Splendid tutorial link, thx for posting!
~Just because you can doesn’t mean you should~
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You’re welcome but it’s all Eugenia’s hard work. 😉
~jr
http://www.johnrofrano.com
http://www.vasst.com -
Something to try is using the beat frequency effect to give you instant “slow motion” footage without any editing trickery.
I haven’t tried this, but theoretically you can shoot the speaker at say 60p or 60i, and feed the speaker with a sine wave at slightly higher or lower than 60Hz (or 120Hz, whatever gives the largest cone excursion safely). If the shutter speed is high enough (use lots of light), you’ll get sharp video and the cone will appear to move slowly because each frame is taken at a slightly different point on successive sine cycles.
If you play a 61Hz (or 120.5Hz) sine through the speaker, you’ll get video in which the speaker appears to be playing a 1Hz sine (the difference of the sine frequency and frame rate). You can adjust the sine frequency to give you the required smooth slow-motion appearance.
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Probably a bit off post but my Sony cam remote has a slo-mo playback in the VTR mode that I can use to re-capture bits that I can then work on. The capture will be at 1/2 speed to begin with. As long as the action is not directly across the field of view, i.e. left to right, it’s fairly smooth, Pete.
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I just tried my method described above and it works quite well – there’s just one major snag…
If you camera suffers from rolling shutter (as mine does), you’ll end up with a very wobbly, flabby looking speaker cone!
For some inspiration, search Youtube or the like for non-Newtonian fluid on speaker cone…
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