How to watch your shots in slow motion
Recording ball positions and time intervals separately turns a “feel” into an observation you can compare.
One thing to remember today
Playing video slowly is not the same as measuring accurately. Set up the same conditions and filming reference first.
Written and edited by TTBoys · How we write and check sources · Report an error
Reading the motion in diagrams
- The same ball's position over time
- Distance covered in equal time
A concept diagram made by TTBoys for learning. It is not a measured graph or simulation result from a paper; arrow lengths and angles are there to explain the principle.
Turning positions seen by the camera into real distances
The 2009 high-speed imaging study tracked ball positions with a camera and image processing. It corrected lens distortion and coordinates and stated the equipment and surface conditions of the experiment.
If you film at an angle, the same real distance looks longer or shorter depending on where it is on screen. The ball’s center sits higher than the cloth, so converting positions from markings on the cloth plane alone can introduce errors. Keep simple observation and quantitative measurement apart.
Look at the distance moved over the same time interval
If the ball’s center moves Δx during a real filming interval Δt, the average speed is Δx/Δt. Use the real time between captured frames, not the slow-motion playback speed.
The picture above shows four moments of the same ball, not four balls. If the distance covered in the same time interval shrinks, the average speed has dropped. This alone cannot tell you the amount of spin or when sliding ended.
Write results and interpretations in different columns
“The first cushion contact was left of the target” is an observation; “there was too much spin” is an interpretation of the cause. Write the observation first, then check the interpretation in the next set by changing only one condition.
Do not force an exact angle from video where the ball is blurred or hidden, or where there are too few frames between collisions. Tracking spin with a dot or logo also needs a clear view and enough frames.
An observation drill suggested by TTBoys
5 reference shots + 5 shots with one condition changed
- Fix the camera and record the ball positions, target, tip position and the feel of the speed. Film from a spot where you do not get in the way of the shot or of other people.
- Repeat the same layout 5 times. Write down each shot’s first-cushion position and next arrival as observed facts.
- Hit 5 more, changing only the tip position or only the speed. Record the difference between the two sets along with any results that did not repeat.
What to watch: Look for differences that show up again and again rather than the single best shot.
When interpreting: The observation exercises on this site do not reproduce the measuring equipment or accuracy of the papers. Do not use the simulator’s paths as ground truth without comparing them with real measurements.
Connect to Basics, Systems and Practice
Evidence from papers and where it applies
Sources reviewed: 2026-10-10 · The explanations and drills are TTBoys' editing.
Experimental and theoretical paper · S. Mathavan · M. R. Jackson · R. M. Parkin
Application of high-speed imaging to determine the dynamics of billiards ↗
American Journal of Physics 77, 788–794 (2009) · DOI 10.1119/1.3157159
What this source explains: Tracks changes in position and velocity in high-speed video to study sliding and rolling, cushion impacts and separation angles.
Limits: The experiments used a snooker table and calibrated camera equipment. This does not mean a smartphone gives the same accuracy, and tracking spin needs separate observation.