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Shooting at higher frame rates is better than lower for future slow mo
Is it better to shoot moderate to fast action scenes at higher frame rates (240 fps) and later speed it up 2-8x to get the desired slow-mo rate than shooting it at slower (120 fps) and slow it down? This is all done with the latest Panasonic Varicam cam.
I done some preliminary export tests of a 240 fps sequence in a 29.97 fps time base, speeding it up 2x in FCPx to get it it to 120 fps and found it’s very hard to tell it apart from a 120 fps originated shot. The 240 fps clip allows 2x slower sequence in case I needed but also can be sped up faster. I also took advantage of speed ramping. The 240 fps clip has more frames to play with and certainly looks smoother than trying to slow down a 120 fps 2x to get it to 240 fps. With no resource limitation on camera media and storage, is this a good thing to do? The cons to this : 2x the storage space needed, more camera media needed on location., and longer offload of footage time.
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3 Replies
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it’ll make a huge difference when you’re slowing stuff down but I can’t see it mattering much when you’re speeding it up to get back to “normal” speed. The obvious disadvantage aside from media storage is that you’ll need way more light to shoot. As a DoP, that would be number one reason for not shooting at any higher frame rate than I had to for any specific shot.
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Jeff Kirkland | Video Producer & Cinematographer
Hobart, Tasmania | Twitter: @jeffkirkland -
There is another downside, the shutter time will be shorter, resulting in less motion blur.
Shooting double frame rate, and in P gives you the option to output interlaced for the normal shots, and better slomo, while having no problems with the motion blur.Bouke
http://www.videotoolshed.com -
I’ve been sticking to the following frame rate to get the most motion blur as possible on the Varicam:
Low action shot:
38-59 fps: 1/60s, 180 deg allowable minimum shutterMedium action shot:
60-96 fps: 1/100s allowable minimum shutterHigh action shot:
120-240fps: 1/250 allowable minimum shutterAt first the reduced motion blur is a shock to get used to. But after a while, I’m used to it. It passed qc because qc mostly concerned with constant frame rate and not shutter angle or speed. But artistic intention is not the same when you have a 360 deg shutter angle. It looks sharp and fast-action like. There is a mathematical proportion with frame rate and shutter speed. I found at 48-59 fps is a good compromise to get some slow mo while having the ability to use the clip as regular motion with 180 deg shutter motion blur. The motion blur is there, but not as much as 360 deg.
The dual recording medium capability of the Varicam allows me to shoot both high frame rate and standard (29.97fps) with full 4-track audio. I compared the high frame rate by speeding it up on FCP X and the actual recorded frame rate. They all mathematically virtually identical to each other. That is a good thing because of more ability to ramp in and out with higher frame rate. Trying to slow a super fast motion on a 29.97fps footage is not the same as shooting it at 240 fps to begin with.
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