At The USTA Training Center (Page 4)

One of the first questions we asked students to consider was what type of equipment or cameras would it take to conduct our experiments. We determined that for the ball/court interaction, we could use the same high speed digital camera we used at the Open. This allowed us to film at 250 frames a second, with a shutter speed of 1/2000. That's more than 8 times the information of regular video cameras that record at 30 frames a second.

This meant that when we zoomed the camera in to take a close look at the ball bounce and the change in spin, we could still recorded 35-50 individual pictures (or video frames) of the event. This gave us the amount of raw data we needed to make all our calculations.