Getting Good Slow Motion Video
Video is one of my favorite things to play with because there are a ton of challenges in learning how to get the most out of the video content as possible. One of the really tricky things is to good really good slow motion effects. Quite often you just slow the video down and all you get is a blurry or smeared looking result that isn’t very watchable. To get the best looking slow motion, there are a few tricks to use that can make a huge difference.
Shoot it Fast
Probably the key thing to getting good slow motion is to shoot the video as fast as possible, this will give you more data to work with. A Canon EOS 7D or 5D Mk II can shoot at 60fps but only in 720p mode. In full 1080p mode these cameras max out at 24fps. This is the main reason I bought a Sony NEX 5n over other small cameras, the 5n can do 1080p at 60fps. The more frames available, the more we can slow it down and maintain detail.
Use The Right Shutter Speed
Choosing the right shutter speed is critical to the success of your project. The rule is to use the recipricole of double the frame rate. If you are shooting 24fps you want as close to 1/48th of a second as possible, at 60fps we want 1/120th of a second. I won’t go into a lot of detail on this topic as we have a great article just on video shutter speed at: Why Shutter Speed Matters With DSLR Video. The following video demonstrates the issues of different shutter speeds.
Sloooowing It Down
The final key to good slow motion is choosing the playback speed. This can have a dramatic impact on the final video quality. If you try to slow down the video too much you will just a gooey mess. This is why you want to record as fast as possible. If I am shooting at 24fps and my output is 24fps, as soon as I slow down the video the editing software has to “fake” the in between frames which will cause a loss of detail and the “smear” effect. If I shoot at 60 fps and my output is 24fps, I can slow the video down 40% which would give me the best output possible, as I continue to slow it down, the worse the video quality would get. If I had a camera shooting at 240fps, I could go down to 10% speed with no image quality loss. The following video demonstrates this concept.
In this tutorial we learned that good slow motion output requires a combination of recording at the fastest frame rate possible, using the right shutter speed, and then choosing the right speed to slow the video down. If you have some good slow motion video you have shot, please share it in the comments below.