While both new models are set to record in the traditional 30 FPS system, you can enable the new frame rate or full 60 FPS recording capabilities with just a few taps.
Here's how to activate and use this feature on your iPhone 6 or iPhone 6 Plus:
1. Open the Settings app.
2. Scroll down and tap on Photos & Camera.
3. You will see at the bottom of the options listed, a switch to turn 60 FPS video recording ON/OFF.
Simply tap that switch to enable and activate the feature.
When enabled, you can use the application to record video as you normally would. You can see variations in video quality during the playback, with the 60 FPS clips apparently being smoother.
However, one downside of this new feature is an increased size of the saved video files. No need to worry though because you can always turn the 60 FPS video recording feature OFF anytime.