Slow down Time-Lapse speed on iPhone

The iPhone's time lapse camera will condense to about 20-40 seconds regardless of how long you took video. If you record for less than 10 minutes then the frame capture is 2fps, after 10 minutes it reduces to 1fps, and reduces further at 40 minutes, 80 minutes, and so on. There is currently no way to change the frame rate on your own. If you need more customization to a time lapse shot then you'll want to download an app that gives those type of options.