Advance Physics: Estimate the knee point using deceleration.
During the spindevelopment the ball will make different laps for each turnaround from the beginning of the spin to the very end.
Physics dictate that the ball will lose its force during the spindevelopment where we can take split-times to observe this deceleration.
240 and so on …
This means that we could use the main focus pin and observe the ball each time it pass to observe how large gap we get between the numbers.
At the beginning we will have a tight pattern with later during the spindevelopment get wider.
It also depends on witch rotor speeds we would prefer to play regarding how the pattern will develop.
Personally i have not test this way to estimate the knee point - but i assume some one would be better of just using black numbers as they are due to higher contrast.
The question is if you can pass the magical zone being more then 4 to 5 rev to end.
It is fully possible being 6 rev to end using other known methods.