SloPro for iPhone is a free app that lets you shoot high quality video in slow motion at an amazing 60 frames per second on an iPhone 4S. If you were to simply slow down the iPhone's native 30 frames per second video, video would be super choppy, but SloPro somehow figured out how to make playback really smooth. "There is a bit of a trick to it that nobody else has figured out even though they've tried," app-maker Sand Mountain Studios told Cult of Mac.

Once you open the app, your only real options are to turn slow-mo on and off. You can also turn "Sound FX" on and off as well, but we can't figure out what that means. Once you've shot your video, you can edit the in / out points of the clip, as well as the in / out points for slow-mo. Unfortunately, at this point you cannot import videos from your Camera Roll. There are settings to change the slow-mo effect from "Slow" to "Slower" and finally to "Slowest." The app renders new video incredibly quickly, and lets you export videos straight to Facebook and YouTube in "Small," "Medium," or "Large" quality. An 18-second video at "Slowest" quality will run you about 18MB of space.

The app works flawlessly in its free state, but a $1.99 "Pro" in-app purchase buys you the ability to export your videos to Camera Roll, export raw video at 60 frames per second, and email videos. The in-app purchase also removes the "Shot With SloPro For iPhone" watermark at the bottom of each video you shoot. If you don't have an iPhone 4S, SloPro works on other iPhones and iOS devices, but only shoots at full 60 frames per second on the iPhone 4S.

See below for a video of SloPro in action: