Rhino Motion is designed to take the math out of time lapse creation. For us for instance, if we're out shooting night time lapses, we say "I want to shoot a 4 hour time lapse with 25 second exposures and I want the end clip (once put together in post production software) to be 10 seconds." Motion then calculates the number of shots and the interval needed to make that happen. When you change the value of either exposure or duration Rhino Motion automatically calculates the new max clip length. There is no way to specifically set the interval or number of shots, but here's how to calculate the interval. Interval = Duration divided by (FPS x Playback). Duration and Playback are both in seconds, not minutes. Another way to think about it would be that to increase the interval, you can increase the Duration (the time it takes to go from one end to the other), or shorten the Playback (the number of seconds you want the end clip to be). Both of those would increase the interval between the shots. To shorten the interval, you can shorten the Duration or increase the Playback time.