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Slow Motion (Slomo, Slo-mo, overcranked or whatever you call it)

By October 3, 2011Tips/Techniques
Slow Motion

Most of us know what Slow motion is– it’s the slowing down of the movement in a video or film shot. There’s several ways to accomplish this– by just slowing down the shot in editing, or “over cranking” the shot when you are shooting.

Shooting takes place at 24 frames a second, or 30 frames (or 25 for you PAL users) and some other variations as well. We won’t even get into fields. If I take 24 frames that were meant to display all in one second and I tell the clip to display those 24 frames in 2 seconds, what you’ll basically get is slo-mo that doubles up every frame. It will appear jittery or jerky. Not really ideal. I watched a movie recently and this is the slo-mo they had– it meant they didn’t shoot it for slo-mo and decided in post to do it. I’m not a big fan. But if you want slo-mo and you didn’t shoot it that way, you’ll have to do it.

If I tell the camera to shoot in 48 frames a second, it will be a more fluid slo-mo shot. If I tell it to do 100 frames a second, it will be even slower. Because those 48 or 100 frames will be played back at 24 or 30 frames a second… thus the term “overcrank” on the set for slo-mo. There are the new incredibly slo-mo cameras that shoot 1000 frames a second. They’re usually computer based and you see them in play on shows like “Mythbusters” and “Top Shot.” I’ve even seen them used in a music video.

For DSLR users, it’s been slow motion getting slo-mo. When Canon added video to their beautiful 5D camera, they could not figure out how to do over-cranked– it’s just too much data for the camera to handle. For the next model they created, with slightly smaller chip– the 7D, they were able to double up the processor and provide a 60 frame, but smaller sized picture to give DSLR users a slo-mo option. So you’re shooting in 1920 size and want slow motion– you have to step down to 1280 size to do it. And your only option is 60 frames a second. And you can’t play back in slo-mo– it will look “different” through the viewfinder– because you’re actually seeing a 60 frame per second video. But you need software to re-configure the clip to display it as 24 frames to give it that slo-mo look.

I do believe the cameras will get better in this area– so look out for that.