Gotta love the smartphone...
Great consistency, if you can build your speed upon that you will be deadly.
I just ordered one of these pocket radar guns like Timpa has, so I will see if I can get some speeds to use as a baseline, then see how sling length effects speed, maybe see if I can come up with a ratio or something scientific…
I also just ordered a Cansonic UDV-888, its like a GoPro but cheaper and does more stuff. The only thing is the frame rate, it doesn't go over 60fps so super-slow mo will be a little choppy, but I can still use the iPhone for that.
If anyone is thinking about a GoPro, check the Cansonic out first.