To create super slow motion shots, you need a high speed camera which shoots at a higher frame rate than the standard frame rates of 25, 30 or 60 fps. But with the right tools, you can slow down a footage in post production process using a time remapping plugin no matter at what frame rate you shoot.
There is a standard Time Stretch feature in After Effects to slow down or speed up a video but that only works fine when your video has been captured in high frame rates. If you use that feature to create slow motion out of a standard 25 or 30 fps video, the video will not play smoothly and will start lagging due to loss of frame.
To overcome that, there are 2 time remapping plugins in After Effects that helps in achieving super slow motions. One is the Timewarp plugin which is available in After Effects by default. Other is the Kronos by foundry which is a third party plugin and you need to purchase a license in order to use it.
Though we can say both the plugin does the same job, i.e. slowing down a video but the difference in final output is quite huge.
Difference between Timewarp and Kronos
In a 30 fps video, there are about 30 frames in one second and to create slow motion, new frames have to be generated.
The standard Timewarp plugin adds repeating frames in between those 30 frames to increase the number of frames in a second. Just repeating frames results in very poor quality output with blurring and stuttering.
KRONOS produces far superior results by creating brand new frames using optical flow/motion estimation, and at incredibly high speed. Thus, the final output is pleasing as well as very smooth.
The Video below demonstrates the difference in results between Kronos (Left) and Timewarp (right) plugins.
Which Time Remapping Plugin is better?
Obviously, kronos is far ahead of the Timewarp plugin and is best for slow motion effects and time remapping purposes. Timewarp is a free plugin and it comes pre installed in After Effects but you have to pay around $120 for Kronos. You can also rent the plugin for $28 a month but I recommend buying a permanent license.